[英]How to get SharedPreference from non activity class for non activity
In my Activity class I store some data in a Sharedpreference
. 在我的Activity类中,我将一些数据存储在Sharedpreference
。 My non Activity class has getter and setter to read the Sharedpreference
data. 我的非Activity类具有getter和setter来读取Sharedpreference
数据。 I want use this Data in an another Activity class. 我想在另一个Activity类中使用此数据。 But I get always a Nullpointer exception. 但是我总是得到一个Nullpointer异常。
This is a Code snippet from my Activity class. 这是我的Activity类的代码段。
SharedPreferences prefs;
prefs = getActivity().getSharedPreferences(KEY_NAME_FOR_PREF, 0);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("name", name.getText().toString());
editor.commit();
This is my first non Activity class 这是我的第一个非活动课
private String name;
private Context mContext;
public PdfConsultantContacts(Context context){
mContext = context;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
And this is my second non Activity class. 这是我的第二个非活动课。 Context mContext; 上下文mContext; PdfConsultantContacts contact = new PdfConsultantContacts(mContext); PdfConsultantContacts contact =新的PdfConsultantContacts(mContext);
void initContact() {
SharedPreferences prefs = mContext.getApplicationContext().
getSharedPreferences("app_prefs", 0);
contact.setName(prefs.getString("name", null));
}
When I try to contact.getName();
当我尝试contact.getName();
I get always a Nullpointer exception, but I know that the SharedPreference
are saved correctly. 我总是收到Nullpointer异常,但我知道SharedPreference
正确保存。
Create a class with two static methods and use this throughout your application to store and retrieve data from SharedPreferences. 用两个静态方法创建一个类,并在整个应用程序中使用它来存储和检索SharedPreferences中的数据。
public class Utils {
public static void putStringInPreferences(Context context, String value, String key, String pKey) {
SharedPreferences sharedPreferences = context.getSharedPreferences(pKey, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(key, value);
editor.commit();
}
public static String getStringFromPreferences(Context context,String defaultValue, String key, String pKey) {
SharedPreferences sharedPreferences = context.getSharedPreferences(pKey, Context.MODE_PRIVATE);
String temp = sharedPreferences.getString(key, defaultValue);
return temp;
}
}
Make sure "Code snippet" from your Activity is really executed, you can verify it by print some log. 确保“活动”中的“代码段”已真正执行,您可以通过打印一些日志来对其进行验证。
Make sure the KEY_NAME_FOR_PREF equals "app_prefs". 确保KEY_NAME_FOR_PREF等于“ app_prefs”。
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