handler消息传递机制demo

public class TestHandler extends AppCompatActivity {
    int num = 0;
    private TextView tv;
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(@NonNull Message msg) {
            if (msg.what % 6==0) {
                tv.setText(num + "");
            }else{
                tv.setText(num + "??????");
            }
        }
    };

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.textview_test1);
        tv = findViewById(R.id.testhandlertv);
        init();
    }

    private void init() {
        Button b = findViewById(R.id.testhandlerbutton);
        b.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread() {
                    @SneakyThrows
                    @Override
                    public void run() {
                        while (true) {
                            Thread.sleep(1000);
                            num++;
                            handler.sendEmptyMessage(num);
                        }
                    }
                }.start();
            }
        });
    }
}