JetBrains Academy: hashCode() and equals() - Kamil-Jankowski/Learning-JAVA GitHub Wiki

JetBrains Academy: hashCode() and equals()

Complex numbers:

Here's a class ComplexNumber. You need to override its methods equals() and hashCode(). The method equals() should compare two instances of ComplexNumber by the fields re and im. The method hashCode() must be consistent with your implementation of equals().

Implementations of the method hashCode() that return a constant or do not consider a fractional part of re and im, will not be accepted.

public final class ComplexNumber {
    private final double re;
    private final double im;

    public ComplexNumber(double re, double im) {
        this.re = re;
        this.im = im;
    }

    public double getRe() {
        return re;
    }

    public double getIm() {
        return im;
    }

    @Override
    public boolean equals(Object object){
        if (this == object){
            return true;
        }

        if(!(object instanceof ComplexNumber)){
            return false;
        }

        ComplexNumber number = (ComplexNumber) object;

        return this.re == number.re &&
               this.im == number.im;
    }

    @Override
    public int hashCode(){
        return Objects.hash(re, im);
    }
}

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