使用 SharedPreferences 保存变量使我的应用程序崩溃

Question

I am using the SharedPreferences to save and get my variables to my app when the app closes or starts.

I am using the same type of method/code for all my variables and it works, except for one variable.

I think maybe the problem might be that this variable also is programmed to reset to = 0 at a specific time each day. (I am using BroadcastReceiver for this).

Since this is the only variable that I reset at a specific time, and the same variable crashes when I try to save it with SharedPreferences, there might be something about those two things that make my app angry.

  SharedPreferences settings2= getSharedPreferences(PREFS_NAME,0); 

Specifically this line of code below seems to crash the app

dosesTaken = settings2.getInt("dosesTaken",dosesTaken);

This is the class for the "BroadcastReciver"

import ...

public class AlarmResetTaken extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        MainActivity.dosesTaken = 0;
        MainActivity.setDosage();
        Activity2.takenDoseText.setText (Integer.toString(MainActivity.dosesTaken));
    }
}

This is the method in MainActivity for the "BroadcastReciver"

private void setAlarmResetDose(long timeInMillis) {
    AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(this, AlarmResetTaken.class);    
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this,0,intent,0);    
    alarmManager.setRepeating(AlarmManager.RTC, timeInMillis, AlarmManager.INTERVAL_DAY, pendingIntent);
}

And the method for setting the specific time to reset.

public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
    timeDoseResetHour = hourOfDay;
    timeDoseResetMin = minute;    
    timeDoseResetText.setText( String.format("%02d",hourOfDay) +" : " + String.format("%02d",minute));

        Calendar calendar = Calendar.getInstance();
        calendar.set(
                calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH),
                hourOfDay,
                minute,
                0
        );
        setAlarmResetDose(calendar.getTimeInMillis()); }

This is the error i get:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.dex, PID: 28325
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dex/com.example.dex.MainActivity}: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
        at android.app.SharedPreferencesImpl.getInt(SharedPreferencesImpl.java:302)
        at com.example.dex.MainActivity.onCreate(MainActivity.java:92)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 

 

Answer 1

From the error that you have posted,

java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer

it seems that, the type of dosesTaken is Long and not int . Thus, when you try to get an Integer with the name dosesTaken , it will throw an error.

Thus, to solve the error, either you change

settings2.getInt("dosesTaken",dosesTaken);

to

settings2.getLong("dosesTaken",dosesTaken);

OR

change the type of dosesTaken to int .

Answer 2

Change this -:

settings2.getInt("dosesTaken",dosesTaken);

to-:

settings2.getLong("dosesTaken",dosesTaken);

Answer 3

Was the type of dosesTaken of type long? If it was, chances are it is saved as a long and now you're trying to retrieve it as an int, which results in the ClassCastException. Try and clear your shared preferences and rerun the app.