Unable to instantiate service > java.lang.NullPointerException

Question

I save config with SharedPreferences and load it in class extends Services.

But error appear when I try get values of config, error like:

Unable to instantiate service kr.co.composer.callrecord.recorder.CallRecordService: java.lang.NullPointerException

at line:

final SharedPreferences mSharedPreference= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());

In layout Configuration I save a EditText:

final SharedPreferences prefs = PreferenceManager
        .getDefaultSharedPreferences(this);

serverUrl.setText(prefs.getString("autoSave", ""));
serverUrl.addTextChangedListener(new TextWatcher() {
    @Override
    public void onTextChanged(CharSequence s, int start, int before,
                              int count)
    {
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count,
                                  int after)
    {
    }
    @Override
    public void afterTextChanged(Editable s)
    {
        prefs.edit().putString("autoSave", s.toString()).commit();
    }
});

And in the other class, I want to get this values by this code:

public class CallRecordService extends Service {
    final SharedPreferences mSharedPreference= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    @Override
    public void onCreate() {
        serverURL =(mSharedPreference.getString("autoSave", ""));
    }
}

Move the `mSharedPreference` initialization to inside `onCreate()`, and remove the `final` modifier. — Mike M., Apr 06 '16 at 05:16
Thanks @MikeM. Your answer is working. Please add to answer to accept your answer. Thank you. — Ave, Apr 06 '16 at 06:17
@VănLộc That's cool. Simple fix. You can accept one of the posted answers, if one of them helped you. Thanks, though. Cheers! — Mike M., Apr 06 '16 at 06:46

score 1 · Answer 1 · answered Apr 06 '16 at 05:18

1

You can't call getApplicationContext() before onCreate(). Instead, you can do it like this:

public class CallRecordService extends Service {
    @Override
    public void onCreate() {
        final SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
        serverURL = sp.getString("autoSave", "");
    }
}

answered Apr 06 '16 at 05:18

Doug Stevenson

297,357
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Thanks. I resolved my problem. – Ave Apr 06 '16 at 06:17

IntelliJ Amiya · Accepted Answer · 2016-04-06T06:41:03.117

1

NullPointerException is thrown when an application attempts to use an object reference, having the null value.

Don't

  public class CallRecordService extends Service {
    final SharedPreferences mSharedPreference= PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    // Call this in your onCreate() section .
    @Override
    public void onCreate() {
        serverURL =(mSharedPreference.getString("autoSave", ""));
    }
}

Do

 public class CallRecordService extends Service {
    final SharedPreferences mSharedPreference= 
    @Override
    public void onCreate() {
      PreferenceManager.getDefaultSharedPreferences(getApplicationContext()); // You can pass context here
        serverURL =(mSharedPreference.getString("autoSave", ""));
    }
}

edited Apr 06 '16 at 06:41

answered Apr 06 '16 at 05:44

IntelliJ Amiya

74,896
15
165
198

1

@IntelliJ Just FYI: The OP is talking about a `Service`; you quoted the docs for `Activity`. Also, a `final` field can only be assigned in a constructor. If you meant to show the `mSharedPreference` initialization in `onCreate()`, you need to remove the `final` modifier in the declaration, and add `mSharedPreference =` in front of the first line in `onCreate()`. – Mike M. Apr 06 '16 at 06:38
@MikeM. Sir .Mine mistake .Thanks for your keen info. – IntelliJ Amiya Apr 06 '16 at 06:40

Unable to instantiate service > java.lang.NullPointerException

2 Answers2