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TameHog
TameHog

Reputation: 950

Java variable setting through method

I have a method which takes in 4 floats and modifies the value. Now I would like to set the floats of the parent class to the value that the method took in. Some code:

public void influence(float x, float y, float w, float h){
x += 5; y += 5; w += 5; h += 5;
}

Now that would be called from the parent class like this:

float x = 5, y = 5, w = 5, h = 5;
influence(x, y, w, h);

I would like to set the floats in the parent to the modified method. I know I could return a float[] and then manually set the floats of the parent class to that array but is there a better way to do this? I could also use a class like Rect but that would be like an array.

Upvotes: 2

Views: 101

Answers (2)

Nir Alfasi
Nir Alfasi

Reputation: 53525

You can't change primitives in Java like that because everything in Jave is passed by value - but you can store the value in an array and pass it:

public void influence(float[] arr){
    for (int i=0; i<arr.length; i++){
        arr[i] += 5;
    }
}

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726479

Java does not have a way to pass a reference to a primitive. However, in your situation it would probably be better to avoid it anyway: it appears that the four variables are related to each other.

When several variables are related, they should be instance variables of a single object. Your object probably looks like a rectangular box that has the origin of (x, y), height h, and width w. Make a class for it, and let the method change that class, or return a new instance:

class Rect {
    private final float x, y, w, h;
    public float getX() { return x; }
    public float getY() { return y; }
    public float getW() { return w; }
    public float getH() { return h; }
    public Rect(float x, float y, float w, float h) {
        this.x = x;
        this.y = y;
        this.w = w;
        this.h = h;
    }
}

Then you can write a method returning a new Rect

public Rect influence(Rect inputRect) {
    ...
}

or make Rect mutable, and let influence modify its values.

Upvotes: 2

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