Handler简单使用

public class MainActivity extends AppCompatActivity {

    private TextView tv;
    private Button btn;
    private Handler handler = new Handler( ){
        @Override
        public void handleMessage(Message msg) {
//处理消息运用在主线程
            switch (msg.what){
                case 0x001:
                    int index = msg.arg1;
                    tv.setText( ""+index );
                    break；
            }
        }
    };

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

        tv = (TextView)findViewById( R.id.textView );
        btn = (Button)findViewById( R.id.button );
    }

    public void btnClick(View view){

//使用线程完成
//工作线程是一个匿名类
        new Thread(  ){
            @Override
            public void run() {

                for (int i = 0;i<100;i++){//子线程不允许刷新UI
                    Message message = new Message();
                    message.arg1 = i;
                    message.what = 0x001;//消息的what是消息标识符，必须有
                    handler.sendMessage( message );
                    try {
                        sleep( 1000 );
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }

            }
        }.start();
    }
}