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);
            }
        });
    }
}