參考两篇文章：http://blog.csdn.net/watermusicyes/article/details/47392949

http://blog.csdn.net/droyon/article/details/21275797

recreate能够使用在日间/夜间模式的切换，那么调用recreate()函数将会运行哪些方法呢？

代码：

public class MainActivity extends FragmentActivity implements OnClickListener {private Button btn;private int mTheme;private String THEME = "theme";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);if (savedInstanceState != null) {mTheme = savedInstanceState.getInt(THEME);switchTheme(mTheme);}setContentView(R.layout.activity_main);btn = (Button) findViewById(R.id.btn);btn.setOnClickListener(this);Log.e(MainActivity.class.getName(), "onCreate");}@Override  protected void onSaveInstanceState(Bundle savedInstanceState) {  super.onSaveInstanceState(savedInstanceState);  Log.e(MainActivity.class.getName(), "onSaveInstanceState");savedInstanceState.putInt(THEME, mTheme);} @Overrideprotected void onRestoreInstanceState(Bundle savedInstanceState) {super.onRestoreInstanceState(savedInstanceState);Log.e(MainActivity.class.getName(), "onRestoreInstanceState");}@Overrideprotected void onStart() {super.onStart();Log.e(MainActivity.class.getName(), "onStart");}@Overrideprotected void onResume() {super.onResume();Log.e(MainActivity.class.getName(), "onResume");}private void switchTheme(int theme) {switch (mTheme) {case android.R.style.Theme_Holo_Light:mTheme = android.R.style.Theme_Black_NoTitleBar;break;case android.R.style.Theme_Black_NoTitleBar:mTheme = android.R.style.Theme_Holo_Light;break;default:mTheme = android.R.style.Theme_Holo_Light;break;}setTheme(mTheme);}@SuppressLint("NewApi")@Overridepublic void onClick(View v) {recreate();}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"tools:context="com.example.testandroid.MainActivity" ><Buttonandroid:id="@+id/btn"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="recreate" /></RelativeLayout>

点击recreatebutton能够看到打印相关的信息：

能够看到这里调用recreate方法会比正常启动Activity多调用了onSaveInstanceState和onRestoreInstanceState。而且onSaveInstanceState在onCreate方法之前调用。

注意：（1）

if (savedInstanceState != null) {mTheme = savedInstanceState.getInt(THEME);switchTheme(mTheme);}

这部分代码要在setContentView(R.layout.activity_main)代码之前调用，否则改变不了主题。

（2）recreate()方法是在Android3.0引入的，所以假设在3.0之前使用会出现错误。例如以下图所看到的：