java.lang.NullPointerException while referencing string variable in code

Question

I\'m trying to reference a few strings that I\'ve stored in an xml. I\'m getting this error:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual         


        

Answer 1

private String CLIENT_ID = getString(R.string.MY_CLIENT_ID);

If you initialize the field on class initialization, you are calling getString() before onCreate(), and thus the Context has not initialized. Better use it like this

public void onCreate(final Bundle bundle) {
    // Other code    
    CLIENT_ID = getString(R.string.MY_CLIENT_ID);
}

Also I strongly advise against caching the strings, because you can get wrong translations if the language has changed (this problem already happened to me so I say this from experience). Instead, use getString() whenever you need it.

Answer 2

You need a Context to access your app resources. You're trying to get a resource without having a valid context first. Move your calls to onCreate() method, where your Activity is first created and you have the context:

private String CLIENT_ID;
private String CLIENT_SECRET;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    temp = (TextView) findViewById(R.id.temp);
    CLIENT_ID = getString(R.string.MY_CLIENT_ID);
    CLIENT_SECRET = getString(R.string.MY_CLIENT_SECRET);

    obj = new foo(CLIENT_ID, CLIENT_SECRET, this);
    obj.bar()
}