使用handler倒计时

 点击button暂停

public class MainActivity extends AppCompatActivity {

    @BindView(R.id.button)
    Button button;

    @BindView(R.id.first_textview)
    TextView textView;

    Handler mHandler;

    volatile boolean flag=true;
    Object object=new Object();
    MThread mThread;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ButterKnife.bind(this);


        textView.setText(String.valueOf(1));

        mHandler=new Handler(){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                textView.setText(String.valueOf(msg.what));
            }
        };


        mThread=new MThread();
        mThread.start();

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(!mThread.isAlive()){
                    mThread=new MThread();
                    mThread.start();
                    return;
                }
                if(flag==true){
                    flag=!flag;
                }
                else{
                    synchronized (object){
                        flag=!flag;
                        object.notify();
                    }
                }

            }
        });
    }


    public class MThread extends Thread{
        @Override
        public void run() {
            System.out.println("enter thread");
            for(int i=20;i>=0;i--){
                if(flag==false){
                    synchronized (object) {
                        try {
                            object.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
                System.out.println(i);
                mHandler.sendEmptyMessage(i);
                try {
                    sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

        }
    }


}

两个handler：

public class MainActivity extends AppCompatActivity {

    @BindView(R.id.button)
    Button button;

    @BindView(R.id.textview)
    TextView textView;

    Handler mFirstHandler;
    Handler mSecondHandler;

    volatile boolean flag = true;
    Object object = new Object();
    SecondThread mThread;
    FirstThread mFirstThread;

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

        ButterKnife.bind(this);


        textView.setText(String.valueOf(1));

        mSecondHandler = new Handler(new Handler.Callback() {
            @Override
            public boolean handleMessage(Message msg) {
                textView.setText(String.valueOf(msg.what));
                return true;
            }
        });


        mThread = new SecondThread();
        mThread.start();

        mFirstThread = new FirstThread();
        mFirstThread.start();
    }


    public class SecondThread extends Thread {
        @Override
        public void run() {
            Looper.prepare();
            Looper.loop();
            System.out.println("*****************");
            mFirstHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    mSecondHandler.sendEmptyMessage(msg.what);
                }
            };
        }
    }

    public class FirstThread extends Thread {
        @Override
        public void run() {
            System.out.println("enter first thread");

            for (int i = 20; i >= 0; i--) {
                Message message = Message.obtain();
                message.what = i;
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                mFirstHandler.sendMessage(message);
            }
        }
    }

}

使用ThreadHandler

public class MainActivity extends AppCompatActivity {

    @BindView(R.id.button)
    Button button;

    @BindView(R.id.textview)
    TextView textView;

    Handler mFirstHandler;
    Handler mSecondHandler;
    
    Thread t=new FirstThread();

    volatile boolean flag = true;
    Object object = new Object();
    HandlerThread handlerThread;    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity);

        ButterKnife.bind(this);


        textView.setText(String.valueOf(1));

        mSecondHandler = new Handler(new Handler.Callback() {
            @Override
            public boolean handleMessage(Message msg) {
                textView.setText(String.valueOf(msg.what));
                return true;
            }
        });
        

        handlerThread=new HandlerThread("1");
        handlerThread.start();
        mFirstHandler=new Handler(handlerThread.getLooper()){
            @Override
            public void handleMessage(Message msg) {
                mSecondHandler.sendEmptyMessage(msg.what);
            }
        };

        t.start();
    }

    public class FirstThread extends Thread {
        @Override
        public void run() {
            System.out.println("enter first thread");

            for (int i = 20; i >= 0; i--) {
                Message message = Message.obtain();
                message.what = i;
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                mFirstHandler.sendMessage(message);
            }
        }
    }

}