Attempt to invoke virtual method '' on a null object reference

Question

I'm getting this error "Attempt to invoke virtual method 'java.lang.String eecs1022.caps.Game.qa()' on a null object reference"

I just want to know why im getting this error and how I can work around it.

The game object is returns a string but for some reason it says its a null object. Here is my main class and my game class.

MAIN:

private Game game;
private String question = "";
private String answer = "";
private int score = 1;
private int qNum = 1;


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


public void ask(){

    String apple = game.qa();
    int indexanswer = apple.indexOf("\n");
    answer = apple.substring(indexanswer);
    question = apple.substring(0,indexanswer);

    ((TextView)findViewById(R.id.question)).setText(question);

}

public void onDone (View v){

    if (qNum == 10){
        finish();
    }

    String answerinput = ((EditText)findViewById(R.id.answer)).toString();

    if (answer.equalsIgnoreCase(answerinput)){
        score++;
    }

    String oldlog = ((TextView)findViewById(R.id.log)).toString();
    String a = oldlog + "\n" + "Q# " + qNum + ": " + question + "\n" + "Your answer" + answerinput.toUpperCase() + "\n" + "Correct Answer: " + answer + "\n";
    ((TextView)findViewById(R.id.log)).setText(a);

    qNum++;
    String orange = "SCORE = " + score;
    String banana = "Q# " + qNum;

    ((TextView)findViewById(R.id.score)).setText(orange);
    ((TextView)findViewById(R.id.qNum)).setText(banana);

    ask();
}

}

GAME:

         public class Game {

public String capitalanswer = "";
public String countryanswer = "";

private CountryDB db;

public Game(){
    this.db = new CountryDB();
}

public String qa(){

    List<String> countries = db.getCapitals();
    int n = countries.size();
    int index = (int)( n * Math.random());
    String c = countries.get(index);
    capitalanswer = c;
    System.out.println(capitalanswer);

    Map<String, Country> data = db.getData();
    Country ref = data.get(c);
    countryanswer = ref.toString();
    System.out.println(countryanswer);

    if (Math.random() < 0.5){
        return "What country has the capital " + ref.getCapital() + " ?" + "\n" + ref.getName();
    }else{
        return "What is the capital of " + ref.getName() + " ?" + "\n" + ref.getCapital();
    }

}

}

Any help is appreciated!

Answer 1

By doing this: private Game game;

You declare the variable game, but you don't actually initialise it. That tells the compiler that you will be using game to refer to a variable whose type is Game. However, you don't actually give a value to game. That is why game is null.

To initialise game, you should be doing this instead: private Game game = new Game();