public class MainActivity extends AppCompatActivity {

    public static final int UPDATE_TEXT =1 ;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ((Button) findViewById(R.id.button)).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Message message =new Message();
                        message.what =UPDATE_TEXT;
                      handler.sendMessage(message);
                    }
                }).start();

            }
        });
    }
    private Handler handler =new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch(msg.what){
                case UPDATE_TEXT:
                    ((TextView) findViewById(R.id.textView)).setText("2333333");
                    break;
            }
        }
    };
}