java ThreadPool

package com.karl.threadpool;



import java.util.ArrayList;

import java.util.Collections;

import java.util.List;



public class MyThreadPool {



    List<MyTask> tasks = Collections.synchronizedList(new ArrayList<MyTask>());



    private static MyThreadPool instance = MyThreadPool.getInstance();



    public static MyThreadPool getInstance() {

        if (instance == null) {

            instance = new MyThreadPool();



        }

        return instance;

    }



    private WorkThread[] threads;



    private MyThreadPool() {

        threads = new WorkThread[10];

        for (int i = 0; i < 10; i++) {

            threads[i] = new WorkThread();

        }

    }



    public void addTask(MyTask task) {

        synchronized (tasks) {

            tasks.add(task);

            tasks.notifyAll();

        }

    }



    class WorkThread extends Thread {



        public WorkThread() {

            start();

        }



        @Override

        public void run() {

            while (true) {

                synchronized (tasks) {

                    if (tasks.isEmpty()) {

                        try {

                            // When call the method wait or notify of a Object,

                            // must ensure the Object is synchronized.

                            // Here let the Thread which use the object wait a

                            // while.

                            tasks.wait(20);

                            continue;

                        } catch (InterruptedException e) {

                        }

                    }

                    MyTask r = tasks.remove(0);

                    if (r != null) {

                        if (r.needRunImmde()) {

                            new Thread(r).start();

                        } else {

                            r.run();

                        }

                    }

                }

            }

        }

    }



}

package com.karl.threadpool;



public abstract class MyTask implements Runnable{

    protected abstract boolean needRunImmde();

    public void run(){

        

    }

}

package com.karl.threadpool;



public class PrintNumber extends MyTask {

    

    private int index;

    private boolean needRunImmde=false;

    

    public boolean isNeedRunImmde() {

        return needRunImmde;

    }



    public void setNeedRunImmde(boolean needRunImmde) {

        this.needRunImmde = needRunImmde;

    }



    public PrintNumber(int index){

        this.index=index;

    }



    @Override

    protected boolean needRunImmde() {

        // TODO Auto-generated method stub

        return needRunImmde;

    }

    

    @Override

    public void run() {

        // TODO Auto-generated method stub

        System.out.println(index);

    }



}

package com.karl.threadpool;



public class Test {

    public static void main(String[] args) throws InterruptedException {

        

        for (int i = 0; i < 10; i++) {

            PrintNumber pn = new PrintNumber(i);

            if((i%2)==0){

                pn.setNeedRunImmde(false);

            }

            

            MyThreadPool.getInstance().addTask(pn);

        }

        Thread.sleep(10000L);

        for (int i = 0; i < 10; i++) {

            PrintNumber pn = new PrintNumber(i);

            if((i%2)==0){

                pn.setNeedRunImmde(false);

            }

            

            MyThreadPool.getInstance().addTask(pn);

        }

    }

}