onCreate中的savedInstanceState

 

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);

    }

}