Android更新UI的两种方法——handler与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：

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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

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FusionField.currentActivity.runOnUiThread(new Runnable()            {                public void run()                {                    Toast.makeText(getApplicationContext(), , "Update My UI",                            Toast.LENGTH_LONG).show();                }                   });