CODEWITHSUNDEEP
javarandom
Joakim Vindenes
Joakim Vindenes

Reputation: 69

Random-generator returns null

I´m working on a Java-program in BlueJ, and I´m using a pseudorandom generator to generate a random number between a max number and a minimum number. I don´t get any syntax errors, but when i call the method it says it´s a null. Does anyone have any idea? I have imported the Random-class and it´s called randomizer in the constructor.

public void attackEnemy()
{
    int damage = 0;
    int max = 41;
    int min = 20;
    damage = randomizer.nextInt(max - min) + min;
    health = health - damage;
}

Upvotes: 2

Views: 2840

Answers (3)

Joe
Joe

Reputation: 4907

You needed to state that randomizer was infact a Random. It also looked like in your original code that you didn't quite complete the calculations. Take a look below:

public void attackEnemy(){

int max = 41;
int min = 20;
Random randomizer = new Random();

int damage = min + (max - min) * randomizer.nextInt();
health = health - damage;
}

I also think that the reason you're receiving a null output, is because you're not returning anything. So you could also display it as the following:

public int attackEnemy(){

int max = 41;
int min = 20;
Random randomizer = new Random();

int damage = min + (max - min) * randomizer.nextInt();
health = health - damage;

return health;
}

Upvotes: 0

Rahul
Rahul

Reputation: 45060

Initialize your randomizer like this:-

randomizer = new Random(); // Without this, it'll throw a NPE

Upvotes: 2

Óscar López
Óscar López

Reputation: 236004

Did you do this?

randomizer = new Random();

The only value that can be null in the snippet shown is the randomizer object. You should instantiate it somewhere else in the class where is being used.

Upvotes: 3

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