Android 更新UI的两种方法——handler和runOnUiThread()

妖狐艹你老母 2022-07-27 16:52 185阅读 0赞

在Android开发过程中，常需要更新界面的UI。而更新UI是要主线程来更新的，即UI线程更新。如果在主线线程之外的线程中直接更新页面显示常会报错。抛出异常：android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

只有原始创建这个视图层次(view hierachy)的线程才能修改它的视图(view)

话不多说，贴出下面的代码

方法一：

在Activity.onCreate(Bundle savedInstanceState)中创建一个Handler类的实例， 在这个Handler实例的handleMessage回调函数中调用更新界面显示的函数。

界面：

![20130222033106300.jpg][]

\[ [html][]\]

<span style="font-size:14px;">public class MainActivity extends Activity \{

private EditText UITxt;

private Button updateUIBtn;

private UIHandler UIhandler;

@Override

public void onCreate(Bundle savedInstanceState) \{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity\_main);

UITxt = (EditText)findViewById(R.id.ui\_txt);

updateUIBtn = (Button)findViewById(R.id.update\_ui\_btn);

updateUIBtn.setOnClickListener(new View.OnClickListener() \{

public void onClick(View v) \{

// TODO Auto-generated method stub

UIhandler = new UIHandler();

UIThread thread = new UIThread();

thread.start();

\});

@Override

public boolean onCreateOptionsMenu(Menu menu) \{

getMenuInflater().inflate(R.menu.activity\_main, menu);

return true;

private class UIHandler extends Handler\{

@Override

public void handleMessage(Message msg) \{

// TODO Auto-generated method stub

super.handleMessage(msg);

Bundle bundle = msg.getData();

String color = bundle.getString("color");

UITxt.setText(color);

private class UIThread extends Thread\{

@Override

public void run() \{

try \{

Thread.sleep(3000);

\} catch (InterruptedException e) \{

// TODO Auto-generated catch block

e.printStackTrace();

Message msg = new Message();

Bundle bundle = new Bundle();

bundle.putString("color", "黄色");

msg.setData(bundle);

MainActivity.this.UIhandler.sendMessage(msg);

\}</span>

更新后：www.2cto.com

![20130222033106978.jpg][]

方法二：利用Activity.runOnUiThread(Runnable)把更新ui的代码创建在Runnable中，然后在需要更新ui时，把这个Runnable对象传给Activity.runOnUiThread(Runnable)。 这样Runnable对像就能在ui程序中被调用。如果当前线程是UI线程,那么行动是立即执行。如果当前线程不是UI线程,操作是发布到事件队列的UI线程

\[html\]

FusionField.currentActivity.runOnUiThread(new Runnable()

public void run()

Toast.makeText(getApplicationContext(), , "Update My UI",

Toast.LENGTH\_LONG).show();

\});

[20130222033106300.jpg]: http://up.2cto.com/2013/0222/20130222033106300.jpg
[html]: http://www.2cto.com/kf/qianduan/css/
[20130222033106978.jpg]: http://up.2cto.com/2013/0222/20130222033106978.jpg