Android Studio 入门 线程篇

private TextView textView;
static boolean showtime=true;
private android.os.Handler handler=new android.os.Handler(){
    public void handleMessage(Message msg){
        switch (msg.what){
            case 0x123:
                textView.setText(msg.obj.toString());break;
            case 0x1234:
                textView.setText("OK?");break;
            default:break;
        }
    }
};

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_first);

Button button=(Button)findViewById(R.id.button_top);
textView=(TextView)findViewById(R.id.text_top);
final Thread threadShowTime=new Thread(new Runnable() {
    @Override
    public void run() {

            while (true) {
                try {
                    Thread.sleep(1000);
                    Message msg = new Message();
                    msg.what = 0x123;
                    msg.obj = new Date().toString();
                    Message msg1=new Message();
                    msg1.what=0x1234;
                    if(showtime)
                        handler.sendMessage(msg);
                    else
                        handler.sendMessage(msg1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

    }
});

button.setOnClickListener(new View.OnClickListener(){
    public void onClick(View v) {
        threadShowTime.start();
        if (showtime) {
            showtime = false;
            String s=String.valueOf(showtime);
            Toast.makeText(FirstActivity.this,s,Toast.LENGTH_SHORT).show();
        } else {
            threadShowTime.interrupt();
            showtime = true;
            String s=String.valueOf(showtime);
            Toast.makeText(FirstActivity.this,s,Toast.LENGTH_SHORT).show();
        }


    }
});