2018年12月29日 星期六

node.js java 連用(g8 王)

const http = require("http");
const net = require("net");

const host = '127.0.0.1';
const port = 8082;

let count = 0;

http.createServer(function (req, res) {
    debugger;
    count++;

    req.on('data', function(){
        debugger;
    });

    req.on('end', async function () {
        debugger;

        console.log('count(%d)', count);
        let data;
        data = await getJavaData(count);

        res.writeHead(200, { 'Content-Type': 'text/html' });

        let content = `<p>${data}</p>`;
        res.end(content);
    });

}).listen(3000);

//======================================
function getJavaData(count) {
    return new Promise(function (res, rej) {
        let data = '';
        let time = 0;

        const client = net.connect(port, host, function () {
            console.log('java connect...');
        });

        client.on('data', function (_data) {
            if (time++ == 0) {
                data = _data.toString();
                console.log('java count(%s) data(%s) data.length', count, data, data.length);
            }
        });

        client.on('end', function () {
            console.log('java end...');
            res(data);
        });
    });
}
//////////////////////////////////////////////////////////////////////////////////////
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package test_5;

import java.io.IOException;
import java.io.PrintStream;
import java.net.*;
import static java.lang.System.out;

/**
 *
 * @author xman
 */
public class Socket_1 {
   
    ServerSocket ss;
    Socket socket;
   
    static int port = 8082;
   
    public Socket_1() throws Exception {
       
            ss = new ServerSocket(port);
            while(true){
                socket = ss.accept();
                out.println("connect");
                PrintStream ps = new PrintStream(socket.getOutputStream());
                ps.println("i am java");
                ps.close();
                socket.close();
                out.println("disconnect");
            }
    }
   
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
       
        try{
        new Socket_1();           
        }catch(Exception e){
            out.println(e.toString());
        }
    }   
}

2018年12月22日 星期六

java promise

https://my.oschina.net/andylucc/blog/608499

http://ifeve.com/promise-future-callback/

https://github.com/hprose/hprose-java/wiki/%E5%BC%82%E6%AD%A5%E7%BC%96%E7%A8%8B%E2%80%94%E2%80%94Promise

https://juejin.im/post/5b126065e51d4506bd72b7cc

https://www.infoq.cn/article/design-patterns-promise https://www.cnkirito.moe/future-and-promise/


interface Closure<E, T> {
    public T callback(E in);
  
    public void error(Error err);
}


public class Promise<E> {
       
    protected int status = 0;   
    protected ArrayList<Closure> jobList = new ArrayList<>();
    protected Closure<Promise, Void> job;
    protected E data;
   
    public Promise(Closure job){
        this.job = job;

        // 暴露 resolve, reject
        this.job.callback(this);
    }

    private Promise() {
       
    }
   
    public void resolve(E e){
       
    }
   
    public void reject(String err){
       
    }
   
    protected void reject(Error err){
       
    }
   
    public Promise done(Closure c){
       
        return (new Promise<E>());
    }
   
    public Promise error(Closure c){
       
        return (new Promise<E>());
    }   
}


2018年12月21日 星期五

java 非同步做法

public interface Callback<T, E> {

    // in: 回傳的資料
    public void back(T in);
  
    // 錯誤時要做的事
    // err 錯誤訊息
    public void error(E err);
}
//----------------------------------------

public class Server_1 {

    public Thread asyncGetData(Callback callback) {
        out.println("server start");
        Thread th_1 = new Thread(() -> {
            int time = (int) (Math.random() * 5000);
          
            out.printf("server thread start(%s)\n", time);
            try {
                Thread.sleep(time);
              
                // 回傳資料
                callback.back(time);
                out.printf("server thread end(%s)\n", time);
            } catch (InterruptedException ex) {
                callback.error(ex);
            }
        });
      
        th_1.start();

        return th_1;
    }
}
//----------------------------------------
public class Client_1 {

    // 資料交換用
    int switchData_int;

    public void getData(){
        out.println("client.getData()");
        Server_1 server_1 = new Server_1();
        int gg;
        Thread th_1 = server_1.asyncGetData(new Callback<Integer, Error>() {
            @Override
            public void back(Integer in) {
                out.println("callback.back");

                // 閉包只適用於套嵌的 class
                Client_1.this.switchData_int = in;
            }

            @Override
            public void error(Error err) {

            }
        });
        try {
            th_1.join();
        } catch (InterruptedException ex) {
            out.println(ex);
        }
        out.printf("result(%s)\n------------\n", this.switchData_int);

    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Client_1 cl = new Client_1();
        cl.getData();
        cl.getData();
    }

}

2018年12月18日 星期二

javascript 另一種模板編組

function compile(template) {
    const evalExpr = /<%=(.+?)%>/g;
    const expr = /<%([\s\S]+?)%>/g;
    template = template.replace(evalExpr, '`); \n echo( $1 ); \n echo(`');
    template = template.replace(expr, '`); \n $1 \n echo(`');
    template = 'echo(`' + template + '`);';

    console.log(template);

    let script =
        `let output = "";
            function echo(html){
            output += html;
            }       
        ${template}
        return output;`;
    return new Function(script);
}


let content = "<ul>\
    <% for(let i=0; i < 4; i++){ %>\
        <li><%= i %>--${i*2}</li>\
    <% } %>\
</ul>";

let res = compile(content);
console.log(res());
console.log('--------------------');
////////////////////////////////////////////////////////////////////////////////////////////////////////////////
https://johnresig.com/blog/javascript-micro-templating/

function compile(template) {
    let functionStr = compile_1(template);

    functionStr = "data = data || {};\n\
        for(let k in data){\n\
            let command = 'var '+ k + '= data[\"'+k+'\"];';\n\
            eval(command);\n\
        }\n\
    " + functionStr;

    console.log(functionStr);
    let fun = new Function('print', 'data', functionStr);

    function print(html) {
        return html;
    }

    return (fun).bind(null, print);
}

function compile_1(template) {
    const expr = /([\s\S]*?)<%([\s\S]+?)%>/g;
    const evalExpr = /([\s\S]*?)<%=([\s\S]+?)%>/g;

    reg_1 = /<%[^=-][\s\S]+?%>/;
    reg_2 = /<%=[\s\S]+?%>/;
    reg_3 = /<%-[^-][\s\S]+?%>/;

    let reg = [];
    reg.push("(" + reg_1.source + ")");
    reg.push("(" + reg_2.source + ")");
    reg.push("(" + reg_3.source + ")");
    reg = reg.join("|");
    reg = `([\\s\\S]*?)(?:${reg})`;
    console.log(reg);
    reg = RegExp(reg, 'g');

    let source = "let source = [];\n";
    template = template.replace(reg, function (m, g1, g2, g3, g4) {
        debugger;
        if (g1) {
            source += `source.push(\`${g1}\`);\n`;
        }

        if (g2) {
            // <% %>
            g2 = g2.replace(/%>$/, '').replace(/^<%/, '');
            source += `\n${g2}\n`;
        } else if (g3) {
            // <%= %>
            g3 = g3.replace(/%>$/, '').replace(/^<%=/, '');
            source += `source.push(print(${g3}));\n`;
        } else if (g4) {
            // <%- %>
            g4 = g4.replace(/%>$/, '').replace(/^<%-/, '');
            source += `source.push(print(${g4}));\n`;
        }

        return '';
    });

    if (template) {
        source += `source.push(\`${template}\`);\n`;
    }

    source += 'return (source.join(""));\n';

    return source;
}


let content = "<ul>\
    <% for(let i=0; i < a.length; i++){ %>\
        <li><%= i*2 %>--${a[i]*2}</li>\
    <% } %>\
</ul>";


let res = compile(content);

console.dir(res);

2018年11月21日 星期三

json deepCopy

// 比 JSON.parse(JSON.stringify(data)) 還略慢

module.exports = deepCopy;

let jobList = [];

// for test
// 與 JSON.stringify() 對比速度用
function deepCopy(value) {
    // debugger;

    let dataSet = new DataSet(value);
    jobList.push(dataSet);

    let index = 0;

    while ((dataSet = jobList[index++]) != null) {
        // debugger;

        let _value = dataSet.originalValue;

        if (Array.isArray(_value)) {
            for (let i = 0; i < _value.length; i++) {
                let v = _value[i];
                let ds = new DataSet(v, dataSet, i);
                jobList.push(ds);
            }

        } else if (typeof (_value) == "object") {
            for (let k in _value) {
                let v = _value[k];
                let ds = new DataSet(v, dataSet, k);
                jobList.push(ds);
            }
        } else {
            continue;
        }
    }
    //-----------------------
    let res;
    let d;

    while ((d = jobList.pop()) != null) {
        res = d;
        d.solve();
    }

    return res.value;
}
//======================================

function DataSet(v, p, k) {

    this.parent; // DataSet
    this.parentKey;
    this.value;
    this.originalValue;

    this.__construct(v, p, k);
}

(function () {
    this.__construct = function (v, p, k) {

        this.originalValue = v;

        if (p) {
            this.parent = p;
            this.parentKey = k;
        }

        this._makeValue();
    };
    //--------------------------------------
    this._makeValue = function () {
        if (Array.isArray(this.originalValue)) {
            this.value = [];
        } else if (typeof (this.originalValue) == "object") {
            this.value = {};
        } else {
            this.value = this.originalValue;
        }
    };
    //--------------------------------------
    this.solve = function () {

        if (this.parent == null) {
            return;
        }

        let data = this.parent.value;
        data[this.parentKey] = this.value;

        this._destory();
    };
    //--------------------------------------
    this._destory = function () {
        this.parent = undefined;
        this.parentKey = undefined;
        this.value = undefined;
        this.originalValue = undefined;
    };
}).call(DataSet.prototype);


2018年11月13日 星期二

java 從網址取得 json data 並解析


package test_4;

import org.json.*;
import java.net.*;
import java.io.*;
import static java.lang.System.out;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author xman
 */
public class T_1 {

    public static String getURLContent(String urlPath) throws MalformedURLException, IOException {
        String content = "";
        HttpURLConnection connection = null;
        BufferedReader in;

        URL url = null;

        url = new URL(urlPath);

        URLConnection urlConnection = url.openConnection();

        if (urlConnection instanceof HttpURLConnection) {
            connection = (HttpURLConnection) urlConnection;
        } else {
            System.out.println("请输入 URL 地址");
            return content;
        }
        in = new BufferedReader(
                new InputStreamReader(connection.getInputStream()));

        String current;
        while ((current = in.readLine()) != null) {
            content += current;
        }

        return content;
    }

    public static void main(String[] args) throws Exception {
        String htmlContent = getURLContent("http://localhost:8081/test_1/JSON/t_1.php");

        // out.println(htmlContent);
        JSONObject j;

        j = new JSONObject(htmlContent);

        Iterator<String> it = j.keys();;

        while (it.hasNext()) {
            String key = it.next();

            Object o_1 = j.get(key);
            out.printf("(%s)=>(%s)\n", key, o_1.toString());
        }
    }
}

java 閉包 範例

package test_4;

import static java.lang.System.out;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author xman
 */
public class T_2 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        int a = 5;

        T2_Closure t = (new T2_Closure<Object, Void>() {
            @Override
            public Void callback(Object in) {

                // 引用 a
                out.printf("callback(%s)\n", a);
                return null;
            }
        });

        t.callback(null);
        //------------------------------------

        T2_Query q = new T2_Query();

        q.query(new T2_Closure<T2_Query, Void>() {
            @Override
            public Void callback(T2_Query in) {

                String res = in.name + " : " + a;
                out.println(res);
                return null;
            }
        });
    }
}
//--------------------------------------
// 閉包

interface T2_Closure<T, E> {

    public E callback(T in);
}

//--------------------------------------

class T2_Query {

    String name = "xyz";

    void query(T2_Closure closure) {

        Thread th = new Thread(() -> {

            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                out.println(e);
            }
            closure.callback(T2_Query.this);
        });

        th.start();
      
        out.println("thread start");
    }
}

java library

https://stleary.github.io/JSON-java/

https://github.com/stleary

2018年11月10日 星期六

java callback


/**
 *
 * @author xman
 */
public class Tt {

    String name = "......";

    void query(Tool t) {
        t.set(this);
    }

    public static void main(String[] args) {
        Tt tt = new Tt();

        tt.query(new Tool<Tt>() {
            public void set(Tt o) {
                out.println(o.name);
            }
        });

        tt.query((o) -> {
            // error
            out.println(o.name);
        });
    }
}

interface Tool<T> {

    public void set(T in);
}

java 非同步呼叫 callback




public class Ajax_1 {

    Callback callback;

    String name;

    void query(Callback callback) {
        this.callback = callback;
      
        // 非同步
        Thread t = new Thread(() -> {
           
            // 取得查詢
            String name = (new SyncSqlQuery()).query();
            Ajax_1.this.name = name;
            Ajax_1.this.callback.callback();
        });

        t.start();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Ajax_1 a = new Ajax_1();
        int x = 5;
       
        a.query(() -> {
            // 及時命令
            out.println(a.name);
        });
       
       
        a.query(new Callback(){
            public void callback(){
                // 及時命令
                out.println(a.name);
            }
        });

    }

}
//-------------------------------------------------------

public interface Callback {
    void callback();
}
//-------------------------------------------------------
public class SyncSqlQuery {
    public static int id = 0;
   
    String query(){
       
        return "SyncSqlQuery_" + id++;
    }
}
//////////////////////////////////////////////////////////////////////////

/**
 *
 * @author xman
 */
public class Ajax_1 {

    String name;

    void query(Callback callback) {       

        Thread t = new Thread(() -> {
           
            // 取得查詢
            String name = (new SyncSqlQuery()).query();
            Ajax_1.this.name = name;
        });

        t.start();
        try {
            t.join();
        } catch (InterruptedException ex) {
            out.println(ex);
        }

        callback.callback();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Ajax_1 a = new Ajax_1();
        int x = 5;
       
        a.query(() -> {
            out.println(a.name);
        });
       
       
        a.query(new Callback(){
            public void callback(){
                out.println(a.name);
            }
        });
    }
}

java inner-class 閉包

// 運用 innerClass

public class T_4 {

    String name;

    String getName() {
        return name;
    }
    //----------------------------
    class A {
        public void setName(String name) {
            T_4.this.name = name;
        }
    }
    //----------------------------
    public static void main(String[] args) {
        T_4 t = new T_4();
        T_4.A a = t.new A();

        a.setName("Xman");
        out.println(t.getName());
    }
}
/////////////////////////////////////////////////////////////////////////////////////////////
// 運用 lambda
// 比較方便偷懶

interface Callback {
    // callback 內容隨你寫....讚
    public void callback(String name);
}
//-------------------------------------------
public class T_4 {

    String name;

    String getName() {
        return name;
    }

    // 送出一個 callback
    // 來設定 name
    Callback getCallback() {

        // lambda 生成一個 匿名 class implements Callback
        return ((name) -> {
            T_4.this.name = name;
        }
);
    }

    // ----------------------------
    public static void main(String[] args) {
        T_4 t = new T_4();

        // 藉由 callback 設定 t
        t.getCallback().callback("Xyz");

        out.println(t.getName());
    }
}

2018年11月9日 星期五

java繼承 與變數型態 間的問題

public class T_1 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        T_1_B b = new T_1_B();
        b.showName();

        T_1_A a = b;

        a.showName();

        try {
            a.getName(); // error
        } catch (Exception e) {
            out.println(e);
        }

    }
}
//--------------------------------
class T_1_A {

    String name = "G";

    void showName() {
        out.printf("A(%s)\n", name);
    }
}
//--------------------------------
class T_1_B extends T_1_A {

    void showName() {
        String _name = this.getName();
        out.printf("B(%s)\n", name);
    }

    String getName() {
        return name;
    }
}

2018年11月3日 星期六

Java中對象的類型判斷

Java中對象的類型判斷


instanceof

判斷一個對象是否是一個類的實例,用Java中自帶的關鍵字instanceof似乎可以做到(僅從關鍵字名稱上可以猜測出),如下面的代碼:

public static void main(String args[]) {
    Object i = new Integer(7);
    if (i instanceof Number) {
        System.out.println("Integer i is a Number");
    } else {
        System.out.println("Integer i isn't a Number");
    }

    if (i instanceof Serializable) {
        System.out.println("Integer i is a Serializable");
    } else {
        System.out.println("Integer i isn't a Serializable");
    }

    if (i instanceof Integer) {
        System.out.println("Integer i is an Integer");
    } else {
        System.out.println("Integer i isn't an Integer");
    }

    if (i instanceof Float) {
        System.out.println("Integer i is a Float");
    } else {
        System.out.println("Integer i isn't a Float");
    }
}



類定義部分為:

public abstract class Number implements java.io.Serializable {}
public final class Integer extends Number implements Comparable<Integer> {}


運行結果:

    Console Output :
    Integer i is a Number
    Integer i is a Serializable
    Integer i is an Integer
    Integer i isn't a Float

然而好像和預期的不太一樣,能看出,使用該關鍵字不僅可以判斷對象是否是某個類的實例,甚至連該類繼承的基類和實現的接口也都能夠被識別為true,雖然這樣在邏輯上沒有任何問題,是可以把Integer當做一個Number來看來用,也當做一個Serializable來看來用,但是這樣返回的結果就沒有針對性了,太過於模糊,我們如果僅僅需要i instanceof Integer為true該怎麼做呢?
Class.equals

還好在Java有一個叫做Class的類,這是一個用來描述類信息的類,我們如果要精確判斷一個對象是否是具體的一個類的實例,可以這麼做:

public static void main(String args[]) {
    Object i = new Integer(7);
    if (i.getClass().equals(Number.class)) {
        System.out.println("Integer i is a Number");
    } else {
        System.out.println("Integer i isn't a Number");
    }

    if (i.getClass().equals(Serializable.class)) {
        System.out.println("Integer i is a Serializable");
    } else {
        System.out.println("Integer i isn't a Serializable");
    }

    if (i.getClass().equals(Integer.class)) {
        System.out.println("Integer i is an Integer");
    } else {
        System.out.println("Integer i isn't an Integer");
    }

    if (i.getClass().equals(Float.class)) {
        System.out.println("Integer i is a Float");
    } else {
        System.out.println("Integer i isn't a Float");
    }
}

2018年11月2日 星期五

java 區域變數的問題

int[] d = {5, 10, 60};

        int[] t = new int[1];
        int y; // 會有問題
       
        for (int i = 0; i < d.length; i++) {
            t[0] = d[i];
            y = d[i];
        }
       
        System.out.println("(%d, %d)",t[0], y);

2018年10月25日 星期四

java String, char 間的轉換

String str = "abc";
char[] bm;

// String 轉 char[]
bm = str.toCharArray();

// char[] 轉 String
str = String.valueOf(bm);

簡化 java System.out.print.*

import static java.lang.System.out;
//////////////////////////////////////////////////////
package com.xyz.util;

import java.io.*;

/**
 *
 * @author xman
 */
public class Out {

    public static void println(Object obj) {
        System.out.println(obj);
    }
    //--------------------------------------------------------------------------
    // 换行输出
    public static void println() {
        System.out.println();
    }
    //--------------------------------------------------------------------------
    // 不换行输出,
    public static void print(Object obj) {
        System.out.print(obj);
    }
    //--------------------------------------------------------------------------
    public static void printf(String format, Object... args) {
        System.out.printf(format, args);
    }
}

2018年10月17日 星期三

visual studio code debbuger

{
    // 使用 IntelliSense 以得知可用的屬性。
    // 暫留以檢視現有屬性的描述。
    // 如需詳細資訊,請瀏覽: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "type": "java",
            "name": "java Debug (Launch)",
            "request": "launch",
            "cwd": "${workspaceFolder}",
            "console": "internalConsole",
            "stopOnEntry": false,
            "mainClass": "",
            "args": ""
        },
        {
            "name": "nodejs Launch Program",
            "type": "node",
            "request": "launch",
            "program": "${workspaceFolder}/app.js"
        },
        {
            "name": "nodejs: Current File",
            "type": "node",
            "request": "launch",
            "program": "${file}"
        },
        {
            "name": "Python: Current File (Integrated Terminal)",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal"
        },
        {
            "name": "Python: Attach",
            "type": "python",
            "request": "attach",
            "port": 5678,
            "host": "localhost"
        },
        {
            "name": "Python: Django",
            "type": "python",
            "request": "launch",
            "program": "${workspaceFolder}/manage.py",
            "console": "integratedTerminal",
            "args": [
                "runserver",
                "--noreload",
                "--nothreading"
            ],
            "django": true
        },
        {
            "name": "Python: Flask",
            "type": "python",
            "request": "launch",
            "module": "flask",
            "env": {
                "FLASK_APP": "app.py"
            },
            "args": [
                "run",
                "--no-debugger",
                "--no-reload"
            ],
            "jinja": true
        },
        {
            "name": "Python: Current File (External Terminal)",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "externalTerminal"
        }
    ]
}

2018年10月2日 星期二

jquery 靜態工具

camelCase: 把 style key 化為駝峰

cleanData: 清除  $.data() 資料

cssHooks:  css 設定提取所需要的特殊處理

cssNumber:  哪些 css 是數值類

attrHooks:  處理頑疾 attr

support:  檢測瀏覽器的支援

valHooks:  針對 table value

contains(context, elem):  context 是否包含 elem

easing:  動畫用的運動函式

$.css:

$.style:

parseHTML(內文, context, option): context 通常指 document, option 若內文含 script 是否要執行

2018年9月26日 星期三

jq 偌多個組件需要統一使用 queue

// queue 的統一者
            const queue_1 = {
                name: "queue"
            };
            function t_1() {
                $(queue_1).queue(function (next) {
                    $("#box_1").animate({
                        left: "+=5%"
                    }, {
                        duration: 1000,
                        queue: false,
                        complete: function () {
                            next();
                        }
                    })
                });
            }

2018年8月29日 星期三

php 正則易碰到的問題

$s = '/a/b';

printf('<p>%s</p>', $s);
var_dump($s);

$res = preg_replace('/\//', '@', $s);

printf('<p>%s</p><hr>', $res);

//----------------------------

$s = '\\a\\b';
printf('<p>%s</p>', $s);
var_dump($s);

$res = preg_replace('/\\\\/', '@', $s);

printf('<p>%s</p><hr>', $res);
//----------------------------

$s = '\a\b';
printf('<p>%s</p>', $s);
var_dump($s);

$res = preg_replace('/\\\\/', '@', $s);

printf('<p>%s</p><hr>', $res);
----------------------------------------------------------

'/\\\\/' => php string = /\\/ => reg = /\/(匹配 '\')
'///' => php string = /// =>  reg = error
'/\//' => php string = /\// => reg = ///(匹配 '/')

----------------------------------------------------------
對 php preg來說  (/) 也屬於保留字
 ----------------------------------------------------------

PHP的跳脫字元



 對 "" 來說,對''無用
\$    顯示金錢符號 $
\"    顯示雙引號符號 "
\'    顯示單引號符號 '
\\    顯示倒斜線符號 \
\b    Backspace鍵
\n    換行符號<br>
\r    Return 歸位字元
\t    Tab鍵
\000 ~ \377    以16進位表示某一個字元
\x00 ~ \xFF    以8進位表示某一個字元

單引號 ' ' 是連跳脫字元都不處理,也就是 \n 會當成 \ 和 n ,而不是換行!這點要特別注意!很多 bug 就是由此而來,例如 str_replace \n 沒有作用之類的。
附帶一提,雖然單引號 ' ' 裡面不處理跳脫字元,但在單引號 ' ' 裡面要寫 (') 或 (\) 還是要記得跳脫一下,不然 PHP 會無法判斷字串結尾︰
<?php
  echo '\''; // 會印 '
  echo '\\'; // 會印 \
?> 
 

PHP preg_quote() 函數

PHP 正則表達式(PCRE)PHP 正則表達式(PCRE)
preg_last_error 函數用於轉義正則表達式字符。

語法

string preg_quote ( string $str [, string $delimiter = NULL ] ) preg_quote() 需要參數 str 並向其中 每個正則表達式語法中的字符前增加一個反斜線。 這通常用於你有一些運行時字符串 需要作為正則表達式進行匹配的時候。
正則表達式特殊字符有: . \ + * ? [ ^ ] $ ( ) { } = ! < > | : -
參數說明:
  • $str: 輸入字符串。
  • $delimiter: 如果指定了可選參數 delimiter,它也會被轉義。這通常用於 轉義 PCRE 函數使用的分隔符。 / 是最通用的分隔符。

返回值

返回轉義後的字符串。

實例

實例 1

<?php  
    $keywords = '$40 for a g3/400';
    $keywords = preg_quote($keywords, '/')
    echo $keywords
?>
執行結果轉義了 $ 和 / 特殊字符,如下所示:
返回 \$40 for a g3\/400

將文本中的單詞替換為斜體

<?php //在這個例子中,preg_quote($word) 用於保持星號原文涵義,使其不使用正則表達式中的特殊語義。 $textbody = "This book is *very* difficult to find."; $word = "*very*"; $textbody = preg_replace ("/" . preg_quote($word) . "/", "<i>" . $word . "</i>", $textbody); echo $textbody; ?>
執行結果如下所示:
This book is <i>*very*</i> difficult to find.
 



2018年8月21日 星期二

php 一些取得 object 資訊的 API


get_class(): 取得物件的 className

get_parent_class(): 取得物件繼承者的 className

get_object_vars():  返回類中所有的非靜態屬性

get_class_methods(): 函數的作用是返回由類的方法名組成的數組

2018年7月25日 星期三

php 讓 container 注入模組的方式

class Container {

    public $name = 'a';
    public $age = 19;
    public $load;

    public function __construct() {
        $this->load = new Loader($this);
    }

    public function getName() {
        printf('<p>%s</p>', $this->name);
    }

}

// 注入模組
class Loader {
    public $container;

    public function __construct($container) {
        $this->container = $container;
    }

    public function __get($name) {

        if (isset($this->container->$name)) {
            return $this->container->$name;
        }

    }

}

$a = new Container();

$load = $a->load;
var_dump($load->name);

2018年7月20日 星期五

php 取得最上層的 className

function getParentClassName($o) {
    $res = $o;

    while (TRUE) {

        $ref = new ReflectionClass($res);
        $r = $ref->getParentClass();

        if ($r) {
            $ref = $r;
        } else {
            break;
        }
        // className
        $res = $ref->getName();
    }

    return $res;
}

2018年6月30日 星期六

php &fn

Example1>>

<?php
function &_copy(){
   
    // 函數(&)的目的
    static $data = array();
    return $data;
}


// 呼叫函數還是需要&
$a = &_copy();
$a[] = 5;

// 呼叫函數還是需要&
$b = &_copy();

var_dump($a);
var_dump($b);
------------------------------------------------
Example2>>

function &xyz(Array &$d){
    return $d;
}

$data_1 = array(5, 1, 6);
$data_2 = &xyz($data_1);
//----------------------------
var_dump($data_2);
//----------------------------
sort($data_1);
var_dump($data_2);

2018年6月13日 星期三

gseries.js

function gseries(fn, data) {

    return new Promise(function (res, rej) {
        let it = fn();
        job(data);

        //----------------------------
        function job(d) {

            // 主要要不斷重複的步驟
            let g = it.next(d);
            let p = g.value;
            // p.then(...)

            if (g.done) {
                res(p);
            } else if (p instanceof Promise) {
                p.then(function (d) {
                    job(d);
                }, function (err) {
                    rej(err);
                });
            }else{
                job(p);
            }
        }
    });
}

java extend 的問題

public class A {
    String name = "A";
   
    public void a(){
        System.out.println("i am " + name);
    }
   
    public void getName(){
        System.out.println(name);
    }
}
//=====================================
public class B extends A {
    String name = "B";
   
    public void b(){
        System.out.println("i am " + name);
    }
   
    public void getName(){
        System.out.println("extend " + name);
    }
}
//=====================================
public static void main(String[] args) {
        A a = new B();       
        a.a(); // i am A
        a.getName(); // extend B
        //----------------------------
        B b = (B)a;
       
        b.a(); // 容易出問題 => i am A
        b.getName();  // extend B
        b.b(); // i am B
    }  

2018年6月5日 星期二

讓 js.generator 不斷往下執行

let gseries = require('../node_modules/gseries');

function asynce(index) {
  
    return new Promise(function (res, rej) {
        console.log('index(%s) start', index);
      
        setTimeout(function () {
            console.log('index(%s) end', index);
            res(index);
        }, 3000);
    });
}


function* main() {

    yield asynce(0);

    yield asynce(1);

    return asynce(2);
}


let p = gseries(main);
--------------------------------------------------------
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
module.exports = gseries;

function gseries(fn, data) {

    return new Promise(function (res, rej) {
        let it = fn();
        job(data);

        //----------------------------
        function job(d) {

            // 主要要不斷重複的步驟
            let g = it.next(d);
            let p = g.value;
            // p.then(...)

            if (g.done) {
                res(p);
            } else if (p instanceof Promise) {
                p.then(function (d) {
                    job(d);
                }, function (err) {
                    rej(err);
                });
            }else{
                job(p);
            }
        }
    });
}

2018年6月2日 星期六

php 檔案鎖定(檔案同步)

PHP flock() 函數

定義和用法

flock() 函數鎖定或釋放文件。
若成功,則返回 true。若失敗,則返回 false。

語法

flock(file,lock,block)
參數 描述
file 必需。規定要鎖定或釋放的已打開的文件。
lock 必需。規定要使用哪種鎖定類型。
block 可選。若設置為 1 或 true,則當進行鎖定時阻擋其他進程。

說明

flock() 操作的 file 必須是一個已經打開的文件指針。
lock 參數可以是以下值之一:
  • 要取得共享鎖定(讀取的程序),將 lock 設為 LOCK_SH(PHP 4.0.1 以前的版本設置為 1)。
  • 要取得獨佔鎖定(寫入的程序),將 lock 設為 LOCK_EX(PHP 4.0.1 以前的版本中設置為 2)。
  • 要釋放鎖定(無論共享或獨佔),將 lock 設為 LOCK_UN(PHP 4.0.1 以前的版本中設置為 3)。
  • 如果不希望 flock() 在鎖定時堵塞,則給 lock 加上 LOCK_NB(PHP 4.0.1 以前的版本中設置為 4)。

提示和註釋

提示:可以通過 fclose() 來釋放鎖定操作,代碼執行完畢時也會自動調用。
註釋:由於 flock() 需要一個文件指針, 因此可能不得不用一個特殊的鎖定文件來保護打算通過寫模式打開的文件的訪問(在 fopen() 函數中加入 "w" 或 "w+")。
-----------------------------------------------------------

例子

a_1.php>>

<?php

ob_start();

$filename = "a1.txt";

$file = fopen($filename, "r+");

$res = '';

// 排它性的锁定
if (flock($file, LOCK_EX)) {
    sleep(15);


    while(!feof($file)){
        $res .= fgets($file);
    }
    
    flock($file, LOCK_UN);
} else {
    echo "Error locking file!";
}

fclose($file);

printf('<p>finish(%s)</p>', $res);
----------------------------------------------------------- 

a_2.php>>

 <?php

ob_start();

$filename = "a1.txt";

$file = fopen($filename, "r+");

$res = '';

// 排它性的锁定
if (flock($file, LOCK_EX)) {
    
    while(!feof($file)){
        $res .= fgets($file);
    }
    
    flock($file, LOCK_UN);
} else {
    echo "Error locking file!";
}

fclose($file);

printf('<p>finish(%s)</p>', $res);

2018年5月29日 星期二

Document.execCommand()

https://codepen.io/netsi1964/full/QbLLGW

TinyMCE

https://www-archive.mozilla.org/editor/midas-spec.html

https://www.tinymce.com/
TinyMCE
http://blog.pulipuli.info/2017/08/htmltinymce-online-html-editor.html

https://ckeditor.com/ckeditor-4/

(html5)
http://xing.github.io/wysihtml5/

(html5)
https://archive.codeplex.com/?p=jhtmlarea
https://github.com/crpietschmann/jHtmlArea

(html5)
http://www.nicedit.com/

https://kevinroth.com/rte/
https://kevinroth.com/rte/demo.htm

http://www.freetextbox.com

http://www.unverse.net

http://markitup.jaysalvat.com/home/

http://www.themaninblue.com/experiment/widgEditor/

http://www.freetextbox.com

http://www.wymeditor.org/demo/

http://www.openwebware.com

http://www.xstandard.com

http://www.nicedit.com/index.php


2018年5月25日 星期五

netbeans 8.0.1 修改行间距

https://svenspruijt.nl/themebuilder/

 

C:\Users\{Administrator}\AppData\Roaming\NetBeans\8.0\config\Editors\Preferences 目录下

C:\Users\allen\AppData\Roaming\NetBeans\12.0\config\Editors\Preferences\org-netbeans-modules-editor-settings-CustomPreferences.xml
 

-------------------------------------------------------

 org-netbeans-modules-editor-settings-CustomPreferences.xml 文件

<editor-preferences>
   //原来的代码

/** 添加的代码 -- 开始 */

    <entry javaType="java.lang.Float" name="line-height-correction" xml:space="preserve">
        <value><![CDATA[1.20]]></value>  //间距数值
    </entry>

/** 添加的代码 -- 结束*/
</editor-preferences>


重启netbeans 查看效果
-------------------------------------------------------
更改系統字型大小 >>

....Netbeans/etc/netbeans.conf

 netbeans_default_options="....... --fontsize 17"

-------------------------------------------------------

Open netbeans.conf file (etc folder) and add "--fontsize 28" to netbeans_default_options value.

Example:

netbeans_default_options="--fontsize 28 -J-XX:+UseStringDeduplication -J-Xss2m -J-

baidutemplate

'<p>5</p>\
<% for(var i = 0; i < 5; i++){ %>\
    <% if(i<3){ %>\
        <p>111111</p>\
        <% _template_fun_array.push(x()); %>\
    <% }else{ %>\
        <p>222222</p>\
    <% } %>\
<% } %>'

紅色的地方可化為 echo (x());

2018年5月23日 星期三

https://zh.m.wikipedia.org/zh-tw/%E7%8F%AE%E9%A0%93%C2%B7%E5%88%A9%E6%96%AF%E7%89%B9

2018年5月16日 星期三

矩陣相乘

A(m*n) =

a(11)......a(1n)
.
.
a(m1)......a(mn)
 --------------------------------------
B(n*p) =

b(11)......b(1p)
.
.
b(n1)......b(np)
--------------------------------------
C(n*p) =

c(11)......c(1p)
.
.
c(n1)......c(np)
--------------------------------------
A*B = C
--------------------------------------

c(11) = a(11)*b(11) + ........+ a(1n)b(n1)
.....
c(1p) = a(11)*b(1p) + ........+ a(1n)b(np)
.....
c(mp) = a(m1)*b(1p) + ........+ a(mn)b(np)

2018年5月11日 星期五

php 另一種引入其他 php檔的方法(處理模板,標籤命令的起手)

a.php>>

<?php
$d = 'hi.........';

$content = sprintf('?>%s', file_get_contents('b.php'));



// 解析,並執行 b.php 裡的內容
$s = eval($content);

// 備用,萬一執行裡面沒有 <?php ?>標籤
echo $s;

-----------------------------------------------------------------------------
b.php>>
printf('<h1>d = %s</h1>', @$d);

java eval()


I could advise you to use Exp4j. It is easy to understand as you can see from the following example code:

Expression e = new ExpressionBuilder("3 * sin(y) - 2 / (x - 2)")
    .variables("x", "y")
    .build()
    .setVariable("x", 2.3)
    .setVariable("y", 3.14);
double result = e.evaluate();
 ------------------------------------------------------------------------
 ------------------------------------------------------------------------
 ------------------------------------------------------------------------
package core;

 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;

 public abstract class FunctionSolver {

public static double solveNumericExpression (String expression) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    return solve(expression, new HashMap<>());
}

public static double solveByX (String function, double value) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

    HashMap<String, Double> values = new HashMap<>();
    values.put("x", value);
    return solveComplexFunction(function, function, values);
}

public static double solve (String function, HashMap<String,Double> values) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

    return solveComplexFunction(function, function, values);
}

private static double solveComplexFunction (String function, String motherFunction, HashMap<String, Double> values) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

    int position = 0;
    while(position < function.length()) {
        if (alphabetic.contains(""+function.charAt(position))) {
            if (position == 0 || !alphabetic.contains(""+function.charAt(position-1))) {
                int endIndex = -1;
                for (int j = position ; j < function.length()-1 ; j++) {
                    if (alphabetic.contains(""+function.charAt(j))
                            && !alphabetic.contains(""+function.charAt(j+1))) {
                        endIndex = j;
                        break;
                    }
                }
                if (endIndex == -1 & alphabetic.contains(""+function.charAt(function.length()-1))) {
                    endIndex = function.length()-1;
                }
                if (endIndex != -1) {
                    String alphabeticElement = function.substring(position, endIndex+1);
                    if (Arrays.asList(usableMathMethods()).contains(alphabeticElement)) {
                        //Start analyzing a Math function
                        int closeParenthesisIndex = -1;
                        int openedParenthesisquantity = 0;
                        int commaIndex = -1;
                        for (int j = endIndex+1 ; j < function.length() ; j++) {
                            if (function.substring(j,j+1).equals("(")) {
                                openedParenthesisquantity++;
                            }else if (function.substring(j,j+1).equals(")")) {
                                openedParenthesisquantity--;
                                if (openedParenthesisquantity == 0) {
                                    closeParenthesisIndex = j;
                                    break;
                                }
                            }else if (function.substring(j,j+1).equals(",") & openedParenthesisquantity == 0) {
                                if (commaIndex == -1) {
                                    commaIndex = j;
                                }else{
                                    throw new IllegalArgumentException("The argument of math function (which is "+alphabeticElement+") has too many commas");
                                }
                            }
                        }
                        if (closeParenthesisIndex == -1) {
                            throw new IllegalArgumentException("The argument of a Math function (which is "+alphabeticElement+") hasn't got the closing bracket )");
                        }  
                        String functionArgument = function.substring(endIndex+2,closeParenthesisIndex);
                        if (commaIndex != -1) {
                            double firstParameter = solveComplexFunction(functionArgument.substring(0,commaIndex),motherFunction,values);
                            double secondParameter = solveComplexFunction(functionArgument.substring(commaIndex+1),motherFunction,values);
                            Method mathMethod = Math.class.getDeclaredMethod(alphabeticElement, new Class<?>[] {double.class, double.class});
                            mathMethod.setAccessible(true);
                            String newKey = getNewKey(values);
                            values.put(newKey, (Double) mathMethod.invoke(null, firstParameter, secondParameter));
                            function = function.substring(0, position)+newKey
                                       +((closeParenthesisIndex == function.length()-1)?(""):(function.substring(closeParenthesisIndex+1)));
                        }else {
                            double firstParameter = solveComplexFunction(functionArgument, motherFunction, values);
                            Method mathMethod = Math.class.getDeclaredMethod(alphabeticElement, new Class<?>[] {double.class});
                            mathMethod.setAccessible(true);
                            String newKey = getNewKey(values);
                            values.put(newKey, (Double) mathMethod.invoke(null, firstParameter));
                            function = function.substring(0, position)+newKey
                                       +((closeParenthesisIndex == function.length()-1)?(""):(function.substring(closeParenthesisIndex+1)));
                        }  
                    }else if (!values.containsKey(alphabeticElement)) {
                        throw new IllegalArgumentException("Found a group of letters ("+alphabeticElement+") which is neither a variable nor a Math function: ");
                    }
                }
            }
        }
        position++;
    }
    return solveBracketsFunction(function,motherFunction,values);
}

private static double solveBracketsFunction (String function,String motherFunction,HashMap<String, Double> values) throws IllegalArgumentException{

    function = function.replace(" ", "");
    String openingBrackets = "([{";
    String closingBrackets = ")]}";
    int parenthesisIndex = 0;
    do {
        int position = 0;
        int openParenthesisBlockIndex = -1;
        String currentOpeningBracket = openingBrackets.charAt(parenthesisIndex)+"";
        String currentClosingBracket = closingBrackets.charAt(parenthesisIndex)+"";
        if (contOccouranceIn(currentOpeningBracket,function) != contOccouranceIn(currentClosingBracket,function)) {
            throw new IllegalArgumentException("Error: brackets are misused in the function "+function);
        }
        while (position < function.length()) {
            if (function.substring(position,position+1).equals(currentOpeningBracket)) {
                if (position != 0 && !operators.contains(function.substring(position-1,position))) {
                    throw new IllegalArgumentException("Error in function: there must be an operator following a "+currentClosingBracket+" breacket");
                }
                openParenthesisBlockIndex = position;
            }else if (function.substring(position,position+1).equals(currentClosingBracket)) {
                if (position != function.length()-1 && !operators.contains(function.substring(position+1,position+2))) {
                    throw new IllegalArgumentException("Error in function: there must be an operator before a "+currentClosingBracket+" breacket");
                }
                String newKey = getNewKey(values);
                values.put(newKey, solveBracketsFunction(function.substring(openParenthesisBlockIndex+1,position),motherFunction, values));
                function = function.substring(0,openParenthesisBlockIndex)+newKey
                           +((position == function.length()-1)?(""):(function.substring(position+1)));
                position = -1;
            }
            position++;
        }
        parenthesisIndex++;
    }while (parenthesisIndex < openingBrackets.length());
    return solveBasicFunction(function,motherFunction, values);
}

private static double solveBasicFunction (String function, String motherFunction, HashMap<String, Double> values) throws IllegalArgumentException{

    if (!firstContainsOnlySecond(function, alphanumeric+operators)) {
        throw new IllegalArgumentException("The function "+function+" is not a basic function");
    }
    if (function.contains("**") |
        function.contains("//") |
        function.contains("--") |
        function.contains("+*") |
        function.contains("+/") |
        function.contains("-*") |
        function.contains("-/")) {
        /*
         * ( -+ , +- , *- , *+ , /- , /+ )> Those values are admitted
         */
        throw new IllegalArgumentException("Operators are misused in the function");
    }
    function = function.replace(" ", "");
    int position;
    int operatorIndex = 0;
    String currentOperator;
    do {
        currentOperator = operators.substring(operatorIndex,operatorIndex+1);
        if (currentOperator.equals("*")) {
            currentOperator+="/";
            operatorIndex++;
        }else if (currentOperator.equals("+")) {
            currentOperator+="-";
            operatorIndex++;
        }
        operatorIndex++;
        position = 0;
        while (position < function.length()) {
            if ((position == 0 && !(""+function.charAt(position)).equals("-") && !(""+function.charAt(position)).equals("+") && operators.contains(""+function.charAt(position))) ||
                (position == function.length()-1 && operators.contains(""+function.charAt(position)))){
                throw new IllegalArgumentException("Operators are misused in the function");
            }
            if (currentOperator.contains(function.substring(position, position+1)) & position != 0) {
                int firstTermBeginIndex = position;
                while (firstTermBeginIndex > 0) {
                    if ((alphanumeric.contains(""+function.charAt(firstTermBeginIndex))) & (operators.contains(""+function.charAt(firstTermBeginIndex-1)))){
                        break;
                    }
                    firstTermBeginIndex--;
                }
                if (firstTermBeginIndex != 0 && (function.charAt(firstTermBeginIndex-1) == '-' | function.charAt(firstTermBeginIndex-1) == '+')) {
                    if (firstTermBeginIndex == 1) {
                        firstTermBeginIndex--;
                    }else if (operators.contains(""+(function.charAt(firstTermBeginIndex-2)))){
                        firstTermBeginIndex--;
                    }
                }
                String firstTerm = function.substring(firstTermBeginIndex,position);
                int secondTermLastIndex = position;
                while (secondTermLastIndex < function.length()-1) {
                    if ((alphanumeric.contains(""+function.charAt(secondTermLastIndex))) & (operators.contains(""+function.charAt(secondTermLastIndex+1)))) {
                        break;
                    }
                    secondTermLastIndex++;
                }
                String secondTerm = function.substring(position+1,secondTermLastIndex+1);
                double result;
                switch (function.substring(position,position+1)) {
                    case "*": result = solveSingleValue(firstTerm,values)*solveSingleValue(secondTerm,values); break;
                    case "/": result = solveSingleValue(firstTerm,values)/solveSingleValue(secondTerm,values); break;
                    case "+": result = solveSingleValue(firstTerm,values)+solveSingleValue(secondTerm,values); break;
                    case "-": result = solveSingleValue(firstTerm,values)-solveSingleValue(secondTerm,values); break;
                    case "^": result = Math.pow(solveSingleValue(firstTerm,values),solveSingleValue(secondTerm,values)); break;
                    default: throw new IllegalArgumentException("Unknown operator: "+currentOperator);
                }
                String newAttribute = getNewKey(values);
                values.put(newAttribute, result);
                function = function.substring(0,firstTermBeginIndex)+newAttribute+function.substring(secondTermLastIndex+1,function.length());
                deleteValueIfPossible(firstTerm, values, motherFunction);
                deleteValueIfPossible(secondTerm, values, motherFunction);
                position = -1;
            }
            position++;
        }
    }while (operatorIndex < operators.length());
    return solveSingleValue(function, values);
}

private static double solveSingleValue (String singleValue, HashMap<String, Double> values) throws IllegalArgumentException{

    if (isDouble(singleValue)) {
        return Double.parseDouble(singleValue);
    }else if (firstContainsOnlySecond(singleValue, alphabetic)){
        return getValueFromVariable(singleValue, values);
    }else if (firstContainsOnlySecond(singleValue, alphanumeric+"-+")) {
        String[] composition = splitByLettersAndNumbers(singleValue);
        if (composition.length != 2) {
            throw new IllegalArgumentException("Wrong expression: "+singleValue);
        }else {
            if (composition[0].equals("-")) {
                composition[0] = "-1";
            }else if (composition[1].equals("-")) {
                composition[1] = "-1";
            }else if (composition[0].equals("+")) {
                composition[0] = "+1";
            }else if (composition[1].equals("+")) {
                composition[1] = "+1";
            }
            if (isDouble(composition[0])) {
                return Double.parseDouble(composition[0])*getValueFromVariable(composition[1], values);
            }else if (isDouble(composition[1])){
                return Double.parseDouble(composition[1])*getValueFromVariable(composition[0], values);
            }else {
                throw new IllegalArgumentException("Wrong expression: "+singleValue);
            }
        }
    }else {
        throw new IllegalArgumentException("Wrong expression: "+singleValue);
    }
}

private static double getValueFromVariable (String variable, HashMap<String, Double> values) throws IllegalArgumentException{

    Double val = values.get(variable);
    if (val == null) {
        throw new IllegalArgumentException("Unknown variable: "+variable);
    }else {
        return val;
    }
}

/*
 * FunctionSolver help tools:
 *
 */

private static final String alphabetic = "abcdefghilmnopqrstuvzwykxy";
private static final String numeric = "0123456789.";
private static final String alphanumeric = alphabetic+numeric;
private static final String operators = "^*/+-"; //--> Operators order in important!

private static boolean firstContainsOnlySecond(String firstString, String secondString) {

    for (int j = 0 ; j < firstString.length() ; j++) {
        if (!secondString.contains(firstString.substring(j, j+1))) {
            return false;
        }
    }
    return true;
}

private static String getNewKey (HashMap<String, Double> hashMap) {

    String alpha = "abcdefghilmnopqrstuvzyjkx";
    for (int j = 0 ; j < alpha.length() ; j++) {
        String k = alpha.substring(j,j+1);
        if (!hashMap.containsKey(k) & !Arrays.asList(usableMathMethods()).contains(k)) {
            return k;
        }
    }
    for (int j = 0 ; j < alpha.length() ; j++) {
        for (int i = 0 ; i < alpha.length() ; i++) {
            String k = alpha.substring(j,j+1)+alpha.substring(i,i+1);
            if (!hashMap.containsKey(k) & !Arrays.asList(usableMathMethods()).contains(k)) {
                return k;
            }
        }
    }
    throw new NullPointerException();
}

public static String[] usableMathMethods () {

    /*
     *  Only methods that:
     *  return a double type
     *  present one or two parameters (which are double type)
     */

    Method[] mathMethods = Math.class.getDeclaredMethods();
    ArrayList<String> usableMethodsNames = new ArrayList<>();
    for (Method method : mathMethods) {
        boolean usable = true;
        int argumentsCounter = 0;
        Class<?>[] methodParametersTypes = method.getParameterTypes();
        for (Class<?> parameter : methodParametersTypes) {
            if (!parameter.getSimpleName().equalsIgnoreCase("double")) {
                usable = false;
                break;
            }else {
                argumentsCounter++;
            }
        }
        if (!method.getReturnType().getSimpleName().toLowerCase().equals("double")) {
            usable = false;
        }
        if (usable & argumentsCounter<=2) {
            usableMethodsNames.add(method.getName());
        }
    }
    return usableMethodsNames.toArray(new String[usableMethodsNames.size()]);
}

private static boolean isDouble (String number) {
    try {
        Double.parseDouble(number);
        return true;
    }catch (Exception ex) {
        return false;
    }
}

private static String[] splitByLettersAndNumbers (String val) {
    if (!firstContainsOnlySecond(val, alphanumeric+"+-")) {
        throw new IllegalArgumentException("Wrong passed value: <<"+val+">>");
    }
    ArrayList<String> response = new ArrayList<>();
    String searchingFor;
    int lastIndex = 0;
    if (firstContainsOnlySecond(""+val.charAt(0), numeric+"+-")) {
        searchingFor = alphabetic;
    }else {
        searchingFor = numeric+"+-";
    }
    for (int j = 0 ; j < val.length() ; j++) {
        if (searchingFor.contains(val.charAt(j)+"")) {
            response.add(val.substring(lastIndex, j));
            lastIndex = j;
            if (searchingFor.equals(numeric+"+-")) {
                searchingFor = alphabetic;
            }else {
                searchingFor = numeric+"+-";
            }
        }
    }
    response.add(val.substring(lastIndex,val.length()));
    return response.toArray(new String[response.size()]);
}

private static void deleteValueIfPossible (String val, HashMap<String, Double> values, String function) {
    if (values.get(val) != null & function != null) {
        if (!function.contains(val)) {
            values.remove(val);
        }
    }
}

private static int contOccouranceIn (String howManyOfThatString, String inThatString) {
    return inThatString.length() - inThatString.replace(howManyOfThatString, "").length();
}
 }