onCreate中的savedInstanceState有何具体作用

在activity的生命周期中，只要离开了可见阶段，或者说失去了焦点，activity就很可能被进程终止了！，被KILL掉了，，这时候，就需要有种机制，能保存当时的状态，这就是savedInstanceState的作用。

      当一个Activity在PAUSE时，被kill之前，它可以调用onSaveInstanceState()来保存当前activity的状态信息（在paused状态时，要被KILLED的时候）。用来保存状态信息的Bundle会同时传给两个method,即onRestoreInstanceState() and onCreate().

示例代码如下：

 package com.myandroid.test;

 import android.app.Activity;
 import android.os.Bundle;
 import android.util.Log;

 public class AndroidTest extends Activity {
     private static final String TAG = "MyNewLog";
     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         // If an instance of this activity had previously stopped, we can
         // get the original text it started with.
         if(null != savedInstanceState)
         {
             int IntTest = savedInstanceState.getInt("IntTest");
             String StrTest = savedInstanceState.getString("StrTest");
             Log.e(TAG, "onCreate get the savedInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
         }

         setContentView(R.layout.main);
         Log.e(TAG, "onCreate");
     }

     @Override
     public void onSaveInstanceState(Bundle savedInstanceState) {
       // Save away the original text, so we still have it if the activity
       // needs to be killed while paused.
       savedInstanceState.putInt("IntTest", 0);
       savedInstanceState.putString("StrTest", "savedInstanceState test");
       super.onSaveInstanceState(savedInstanceState);
       Log.e(TAG, "onSaveInstanceState");
     }

     @Override
     public void onRestoreInstanceState(Bundle savedInstanceState) {
       super.onRestoreInstanceState(savedInstanceState);

       int IntTest = savedInstanceState.getInt("IntTest");

       String StrTest = savedInstanceState.getString("StrTest");

       Log.e(TAG, "onRestoreInstanceState+IntTest="+IntTest+"+StrTest="+StrTest);
     }
 }

 

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/xiaoxiao_job/archive/2010/08/31/5852811.aspx