How to compare two array lists for similar objects which differ in at least one property in java?

Question

I have two array list. Each has list of Objects of type User.

The User class looks like below

    public class User {

    private long id;

    pri         


        

Answer 1

Implement equals, hashcode in User

    @Override
    public boolean equals(Object obj) {
        if (obj == null)
            return false;
        if (!(obj instanceof User))
            return false;
        User u = (User) obj;
        return this.empCode == null ? false : this.empCode
                .equals(u.empCode);
    }

    @Override
    public int hashCode() {
        return this.empCode == null ? 0 : this.empCode.hashCode();
    }

    @Override
    public String toString() {
        return "Emp Code: " + this.empCode;
    }

Then use retainAll

list2.retainAll(list1);-->EMP01, EMP02, EMP09, EMP10