从服务访问命名的共享首选项

问题描述

我正在尝试从服务访问SharedPreference并收到一个错误，我在网络上的任何地方都找不到。任何帮助表示赞赏。谢谢。

code sharedPref = getApplicationContext（）。getSharedPreferences（“ FlutterSharedPreferences”，Context.MODE_PRIVATE | Context.MODE_MULTI_PROCESS）;

2020-09-10 21:16:04.057 10186-10186/com.example.demo1 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.demo1,PID: 10186
    java.lang.RuntimeException: Unable to start service com.example.demo1.MorningReset@ce7eae1 with Intent { flg=0x4 cmp=com.example.demo1/.MorningReset (has extras) }: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.os.UserManager.isUserUnlockingOrUnlocked(int)' on a null object reference
        at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:3686)
        at android.app.ActivityThread.access$1600(ActivityThread.java:199)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1681)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.os.UserManager.isUserUnlockingOrUnlocked(int)' on a null object reference
        at android.app.ContextImpl.getSharedPreferences(ContextImpl.java:418)
        at android.app.ContextImpl.getSharedPreferences(ContextImpl.java:404)
        at android.content.Contextwrapper.getSharedPreferences(Contextwrapper.java:174)
        at com.example.demo1.MorningReset.onStartCommand(MorningReset.java:25)

仅当从服务访问SharedPreference时，才会出现此错误。同一行代码在活动中可以正常工作。

解决方法

write data to shared preferences

SharedPreferences sharedPreferences =getSharedPreferences("MySharedPref",MODE_PRIVATE); 
SharedPreferences.Editor myEdit = sharedPreferences.edit(); 
myEdit.putString( "name",name.getText().toString()); 

myEdit.apply(); 

retrieve data from shared preferences

SharedPreferences sh = getSharedPreferences("MySharedPref",MODE_PRIVATE); 
String name = sh.getString("name",""); 
name.setText(name);