Handler四种更新ui的四种方式_handler更新ui-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_52942787/article/details/114573292

本文介绍了在Android应用开发中更新UI的四种常见方法：使用Handler消息传递机制、AsyncTask异步任务、runOnUiThread方法及Handler的post(Runnable)方法。通过具体实例展示了如何在后台线程完成耗时操作后更新主线程的UI。

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1.使用Handler消息传递机制

public class MainActivity extends Activity {

    private ActivityMainBinding mainBinding;

    Handler handler = new Handler(){
        @Override
        public void handleMessage(@NonNull Message msg) {
            if(msg.what==111){
                mainBinding.ivText1.setText("更新后的ui");
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mainBinding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(mainBinding.getRoot());
        new MyThread().start();
    }

    private class MyThread extends Thread{
        @Override
        public void run() {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            handler.sendEmptyMessage(111);
        }
    }
}

使用AsyncTask异步任务


public class MainActivity extends Activity {

    private ActivityMainBinding mainBinding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mainBinding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(mainBinding.getRoot());
        new Yibu().execute();
    }

    private class Yibu extends AsyncTask<String,String,String> {
        @Override
        protected String doInBackground(String... strings) {
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            mainBinding.ivText1.setText("更新后的ui");
        }
    }
}

使用runOnUiThread(action)方法


public class MainActivity extends Activity {

    private ActivityMainBinding mainBinding;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mainBinding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(mainBinding.getRoot());
        new MyThread().start();
    }


    private class MyThread extends Thread {
        @Override
        public void run() {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    try {
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    mainBinding.ivText1.setText("更新后的TextView");
                }
            });

        }
    }
}

使用Handler的post(Runnabel r)方法
`
public class MainActivity extends Activity {

private ActivityMainBinding mainBinding;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mainBinding = ActivityMainBinding.inflate(getLayoutInflater());
setContentView(mainBinding.getRoot());
Handler handler = new Handler();
handler.post(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
mainBinding.ivText1.setText(“更新后的TextView”);
}
});
}
}`