Problems using string for resources

Question

I’m creating an app quiz, the link is https://github.com/luisbalmant/QuickQuiz-Science.

I’m trying to use the getString(R.string.nome) to migrate the java class strings and then be able to use 2 languages.

In other places I managed to pull the strings and is working showing the texts when I run the app on mobile, but the moment I try to use the string in questions the app simply does not open more.

public class Questions {

        public String mQuestions[] = {

// Funciona
                "Pergunta número 1 xxxxxxx",

// NÃO FUNCIONA
                getString(R.string.Q1_function_insulin),

        };

---

=/=/=/=/=/=/=/=/=/=/=/=/=/=/=/=/=/=//=/=/=/=/=/=/=/=

Updating:

I made the following changes and it didn’t work:

My Mainactivity.java:

public class MainActivity extends AppCompatActivity {

    Button answer1, answer2, answer3;

    TextView score, question;

    private Questions mQuestions;

    private String mAnswer;
    private int mScore = 0;
    private int mQuestionsLength;

    Random r;

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

        mQuestions = new Questions(this);
        mQuestionsLength = mQuestions.mQuestions.length;

        r = new Random();

My other Questions.java file

import android.content.Context;

public class Questions extends MainActivity {

    Context context;
    public Questions(Context context)
    {
        this.context = context;
    }

    public String mQuestions[] = {

            "Pergunta número 1 xxxxxxx",
            context.getString(R.string.Q1_function_insulin),
            "Outra Pergunta número 2",

    };

Answer 1

Try this way:

public class Questions {

    private Context context;
    private Integer[] mQuestions = new Integer[]{R.string.Q1_function_insulin, R.string.Q2_any_name};

    public Questions(Context context) {

        this.context = context;
    }

    public String get(int q_number) {
        String question = null;
        try {
            question = context.getString(mQuestions[q_number - 1]);
        } catch (IndexOutOfBoundsException e) {
            Log.e("Question", "Invalid question number: " + q_number);
        }
        return question;
    }
}

In Oncreate declare the class Questions:

Questions mQuestions = new Questions(this);

Get the questions:

String question1 = mQuestions.get(1); //obtém a questão 1 e assim por diante...

Answer 2

The answers already contained can solve the problem, but see below a logical explanation regarding the problem.

The getString() is a method that is contained in the abstract class Context. The reason it’s not working is because you don’t extend this class in the method Questions.

For example, if you create your class public class Questions extends Activity, will function correctly within the method onCreate. See below the scheme:

Activity
    |
    +----> extends ContextThemeWrapper
                       |
                       +----> extends ContextWrapper 
                                        |
                                        +----> extends Context 

Like you said yourself, "In the other places I managed to pull the strings...", precisely because these "..other places.." you are correctly extending the class that contains the method you are using.

Now the solution, there are several, as you can see the answers in your question.

Answer 3

At the time you are using the method getString() the context is null.

Note that you are instantiating the Questions class at the time of the declaration.

public class MainActivity extends AppCompatActivity {

    Button answer1, answer2, answer3;

    TextView score, question;

    private Questions mQuestions = new Questions();

    private String mAnswer;

    ...

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

        r = new Random();
        ...
        ...
    }
    ...
    ...
} 

Although Activity indirectly extends Context, the implementation is delegated to a Context that is passed to the constructor.
How initialization is done in the field declaration,

private Questions mQuestions = new Questions();

it is done before the constructor is executed, hence Context is null.

To solve create the instance in the method onCreate():

public class MainActivity extends AppCompatActivity {

    Button answer1, answer2, answer3;

    TextView score, question;

    private Questions mQuestions;

    private String mAnswer;

    ...

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

        mQuestions = new Questions();

        r = new Random();
        ...
        ...
    }
    ...
    ...
}