Android 更新UI的两种方法——handler和runOnUiThread()
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：
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); } }}
更新后：
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
FusionField.currentActivity.runOnUiThread(new Runnable() { public void run() { Toast.makeText(getApplicationContext(), , "Update My UI", Toast.LENGTH_LONG).show(); } });
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上面的写法让人迷惑:另外写一个实现Runable的类专门用于更新ui
private class UpdateUIFromRunnable implements Runnable{//to do your work......} 调用上面的:
runOnUiThread(new UpdateUIFromRunnable());
既可以实现更新UI了...