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[英]Using onCreate Bundle savedInstanceState with wallpaper service? (Watchface)
[英]Where is Bundle object created in onCreate(Bundle savedInstanceState)
在Android中, onCreate
方法将savedInstanceState
作为Bundle对象的引用。 我只想知道在何处以及如何创建Bundle
对象?
如果您将应用程序的状态保存在捆绑包中(通常在onSaveInstanceState中为非持久性动态数据),那么如果需要重新创建活动(例如,方向更改),则可以将其传递回onCreate,以免丢失此先验信息。 如果未提供任何数据,则saveInstanceState为null。
您需要重写onSaveInstanceState(Bundle savedInstanceState),并将要更改的应用程序状态值写入Bundle参数,如下所示:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putBoolean("MyBoolean", true);
savedInstanceState.putDouble("myDouble", 1.9);
savedInstanceState.putInt("MyInt", 1);
savedInstanceState.putString("MyString", "Welcome back to Android");
// etc.
}
Bundle本质上是一种存储NVP(“名称-值对”)映射的方法,它将被传递给onCreate()以及onRestoreInstanceState(),您可以在其中提取如下值:
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
double myDouble = savedInstanceState.getDouble("myDouble");
int myInt = savedInstanceState.getInt("MyInt");
String myString = savedInstanceState.getString("MyString");
}
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