How do I fix issues with HashSet in my Java application?

I'm having trouble with a HashSet in my Java application. It seems to be not storing unique values.

It sounds like you might be adding duplicate values. Have you checked if the objects you're adding have properly overridden the equals() and hashCode() methods?

I haven't overridden those methods. How do I do that?

You need to implement the equals() method to compare the object's fields and the hashCode() method to return a unique integer for each object based on those fields.

Can you give me an example of how to implement those methods?

Sure! Here's a simple example: for a class Person, you would do something like this:

@Override
public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null || getClass() != obj.getClass()) return false;
    Person person = (Person) obj;
    return Objects.equals(name, person.name) && age == person.age;
}

@Override
public int hashCode() {
    return Objects.hash(name, age);
}