Android菜鳥練習第三十七課 Handler的基本用法

Handler的第一種用法Handler.post()

public class MainActivity extends AppCompatActivity {
    private TextView mTv;
    private Handler handler = new Handler();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTv = (TextView) findViewById(R.id.tv);
        new Thread() {
            @Override
            public void run() {
                //實現業務邏輯
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        //更新UI
                        mTv.setText("Handler的第一種用法");
                    }
                });
                super.run();
            }
        }.start();
    }
}

Handler的第二種用法Handler內部類實現Runnable接口

public class MainActivity extends AppCompatActivity {
    private TextView mTv;
    private Handler handler = new Handler();

    @Override
    protected 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() {
            @Override
            public void run() {
                handler.post(myRunnable);
                super.run();
            }
        }.start();
    }

    public class MyRunnable implements Runnable {

        @Override
        public void run() {
            mTv.setText("Handler的第二種使用方法");
        }
    }
}

Handler的第三種使用方法handlerMessage()方式

public class MainActivity extends AppCompatActivity {
    private TextView mTv;
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 1:
                    mTv.setText("Handler的第三種基本使用方式");
                    break;
            }
            super.handleMessage(msg);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTv = (TextView) findViewById(R.id.tv);
        new Thread() {
            @Override
            public void run() {
                Message message = new Message();
                message.what = 1;
                handler.sendMessage(message);
                super.run();
            }
        }.start();
    }

}