Android菜鸟练习第三十七课 Handler的基本用法

Handler的第一种用法Handler.post()

public class MainActivity extends AppCompatActivity {private TextView mTv;private Handler handler = new Handler();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mTv = (TextView) findViewById(R.id.tv);new Thread() {@Overridepublic void run() {//实现业务逻辑handler.post(new Runnable() {@Overridepublic void run() {//更新UImTv.setText("Handler的第一种用法");}});super.run();}}.start();}}

Handler的第二种用法Handler内部类实现Runnable接口

public class MainActivity extends AppCompatActivity {private TextView mTv;private Handler handler = new Handler();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mTv = (TextView) findViewById(R.id.tv);final MyRunnable myRunnable = new MyRunnable();new Thread() {@Overridepublic void run() {handler.post(myRunnable);super.run();}}.start();}public class MyRunnable implements Runnable {@Overridepublic void run() {mTv.setText("Handler的第二种使用方法");}}}

Handler的第三种使用方法handlerMessage()方式

public class MainActivity extends AppCompatActivity {private TextView mTv;private Handler handler = new Handler() {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case 1:mTv.setText("Handler的第三种基本使用方式");break;}super.handleMessage(msg);}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mTv = (TextView) findViewById(R.id.tv);new Thread() {@Overridepublic void run() {Message message = new Message();message.what = 1;handler.sendMessage(message);super.run();}}.start();}}