动态添加线程，然后监控多个线程是否都完成了

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;

import com.mwf.studyjob.R;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

/**
 * 动态添加线程，然后监控多个线程是否都完成了
 */
public class WatchThreadActivity extends AppCompatActivity {

    private Executor executor;
    private int threadNum = 100;
    private int index = 0;
    private List<Flag> flags = new ArrayList<Flag>();

    private class Flag {
        private int flag;
        private boolean status;
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getFlag() {
            return flag;
        }

        public void setFlag(int flag) {
            this.flag = flag;
        }

        public boolean isStatus() {
            return status;
        }

        public void setStatus(boolean status) {
            this.status = status;
        }
    }


    Handler hander = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            Flag flag = (Flag) msg.obj;
            //对照是哪个线程完成了
            for (int i = 0; i < flags.size(); i++) {
                if (flags.get(i).getFlag() == flag.getFlag()) {
                    flags.get(i).setStatus(true);
                    System.out.println(flags.get(i).getName() + "完成...");
                }
            }

            System.out.println("未完成如下：");
            int lastCount = 0;
            //查看未完成的数量
            for (int i = 0; i < flags.size(); i++) {
                if (!flags.get(i).isStatus()) {
                    lastCount += 1;
                    System.out.println(flags.get(i).getName());
                }
            }
            if (lastCount == 0) {
                System.out.println("全部完成！");
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_watch_thread);

        // 创建固定长度的线程池
        executor = Executors.newFixedThreadPool(threadNum);

    }

    public void start(View view) {
        index++;
        //创建一个线程的标志对象
        Flag flag = new Flag();
        flag.setFlag(index);
        flag.setStatus(false);

        flags.add(flag);

        Runnable runnable = new TestThread(flag);
        executor.execute(runnable);

    }

    private class TestThread implements Runnable {
        private Flag flag;

        public TestThread(Flag flag) {
            this.flag = flag;
        }

        @Override
        public void run() {
            flag.setName(Thread.currentThread().getName());

            System.out.println(Thread.currentThread().getName() + "开始...");
            try {
                Random random = new Random();
                int count = random.nextInt(10) + 1;
                System.out.println(Thread.currentThread().getName() + "睡眠:" + count);
                Thread.sleep(1000 * count);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            //任务完成向Handler发送完成的消息
            Message message = Message.obtain();
            message.obj = flag;
            hander.sendMessage(message);
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="start"
        android:text="增加"/>
</LinearLayout>