Hash Set Question

Hi
I am analysing a particular code and have some questions

Code:

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public class Point { 
    private final int x; 
    private final int y; 
    public Point(int x, int y) { 
        this.x = x; 
        this.y = y; 
    } 
 
} 
 
import java.util.HashSet; 
import java.util.Set; 
 
public class PointMain { 
    public static void main(String args[]){ 
        System.out.println(onUnitCircle(new Point(1, 0))); 
    } 
    // Initialize UnitCircle to contain all Points on the unit circle 
    private static final Set<Point> unitCircle; 
    static { 
        unitCircle = new HashSet<Point>(); 
        unitCircle.add(new Point( 1,  0)); 
        unitCircle.add(new Point( 0,  1)); 
        unitCircle.add(new Point(-1,  0)); 
        unitCircle.add(new Point( 0, -1)); 
    } 
 
    public static boolean onUnitCircle(Point p) { 
        return unitCircle.contains(p); 
    } 
}

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I get a false when i do a contains on a hashset. I am thinking that it should yield true.
The question i had was that without overriding the equals or the hashcode when i store the values in a Hash Set and do a contains i am assuming that it might have the equals and hashcode implemented. Would this be correct then- when i am using the hash set to store my objects the right way to use the contains is that i implement a hashcode and a equals method in object that i am going to do the contains on?

Thanks,
Frank

Quote:

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Originally Posted by frankyfish

without overriding the equals or the hashcode

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You must supply equals and hashCode methods in Point. Otherwise it won't work with the standard hash based collections, such as HashSet.