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