null shared preferences in a class

Question

for some common process for activities I created a class CurrentDate, that get the actual date, for return de date in different local preferences order european (dd/mm/yy), american (mm/dd/yy... I create a some preferences data. int, Strings... the problem is load preferences data in my class, there isn't any onCreate.... because is not an activity, for this reason it doesn't have instance of load shared preferences. and give a null error:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference
    at com.example.ricmac.task2.CurrentDate.<init>(CurrentDate.java:50)

This class, CurrentDate is called from an activity:`

public class CurrentDate {

private static final int PREFS_MODE = 0;
private static final String PREFS_FILE = "pref";


public CurrentDate (Context context){ mContext = context;}

< here the fail in line number 50:

final SharedPreferences settings = mContext.getSharedPreferences(PREFS_FILE, PREFS_MODE);

< continue with code of CurrentDate class

public void checkDate(TextView tstart){
    String iCurrent = mContext.getResources().getString(R.string.actual); // "current"
    String START = tstart.getText().toString(); // get string start date
    int localDatePreferencePosition = settings.getInt(KEY_LOCAL_DATE, 0); // get from shared preferences the preferences 0  European, 1 American,....
    if(START.equalsIgnoreCase(iCurrent)){ // check if it the current default date
        
        tstart.setText(getSetLocalDate(getCurrent(), localDatePreferencePosition,mContext)); // set the date in local format in textView tstar
    }

}

`

complete Error from Logical:

`

2020-10-18 12:18:52.383 25809-25809/com.example.ricmac.task2 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ricmac.task2, PID: 25809
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ricmac.task2/com.example.ricmac.task2.introTaskFullScreen}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
    at android.app.ActivityThread.-wrap11(Unknown Source:0)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6494)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference
    at com.example.ricmac.task2.CurrentDate.<init>(CurrentDate.java:50)
    at com.example.ricmac.task2.introTaskFullScreen.onCreate(introTaskFullScreen.java:184)
    at android.app.Activity.performCreate(Activity.java:7009)
    at android.app.Activity.performCreate(Activity.java:7000)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
    at android.app.ActivityThread.-wrap11(Unknown Source:0) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
    at android.os.Handler.dispatchMessage(Handler.java:106) 
    at android.os.Looper.loop(Looper.java:164) 
    at android.app.ActivityThread.main(ActivityThread.java:6494) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 

`

Answer 1

Your problem is that mContext is null.

Rather than creating the settings object on line 50 when context is null , you could get shared preferences in the checkDate method itself, using the TextView to get a context (tStart.getContext() should work I think)