Java Initialize an int array in a constructor

This is because, in the constructor, you declared a local variable with the same name as an attribute.

To allocate an integer array which all elements are initialized to zero, write this in the constructor:

data = new int[3];

To allocate an integer array which has other initial values, put this code in the constructor:

int[] temp = {2, 3, 7};
data = temp;

or:

data = new int[] {2, 3, 7};

You could either do:

public class Data {
    private int[] data;

    public Data() {
        data = new int[]{0, 0, 0};
    }
}

Which initializes data in the constructor, or:

public class Data {
    private int[] data = new int[]{0, 0, 0};

    public Data() {
        // data already initialised
    }
}

Which initializes data before the code in the constructor is executed.

private int[] data = new int[3];

This already initializes your array elements to 0. You don't need to repeat that again in the constructor.

In your constructor it should be:

data = new int[]{0, 0, 0};

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