android Activity runOnUiThread() 方法使用
在android 中我们一般用 Handler 做主线程 和 子线程 之间的通信 。
现在有了一种更为简洁的写法,就是 Activity 里面的 runOnUiThread( Runnable )方法。
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)。
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。
package com.app; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.widget.Toast; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //创建一个线程 new Thread(new Runnable() { @Override public void run() { //延迟两秒 try { Thread.sleep( 2000 ); } catch (InterruptedException e) { e.printStackTrace(); } runOnUiThread(new Runnable() { @Override public void run() { Toast.makeText(MainActivity.this, "hah", Toast.LENGTH_SHORT).show(); } }); } }).start(); } }
Activity的runOnUiThread(Runnable)
/** * Runs the specified action on the UI thread. If the current thread is the UI * thread, then the action is executed immediately. If the current thread is * not the UI thread, the action is posted to the event queue of the UI thread. * * @param action the action to run on the UI thread */ public final void runOnUiThread(Runnable action) { if (Thread.currentThread() != mUiThread) { mHandler.post(action); } else { action.run(); } }