How to implement equals method correctly?

Consider that you are overriding equals method for Employee Class having empId, firstName and lastName.

1. Check for reference equality, if equal then return true.
2. Check for null check on the object argument being passed, if null return false.
3. Compare getClass methods, if different return false.
4. Always compare numeric and identify fields first.
5. Check for field's references first and then check for null and equality.
6. Override hashcode method whenever you override equals method.

The above steps are illustrated in the below example.

@Override
public boolean equals(Object o) {
    
    if (this == o)  // check 1
        return true;
    // null check
    if (o == null)
        return false;
    // type check and cast
    if (getClass() != o.getClass())
        return false;
    Employee emp = (Employee) o;
    //numeric and identity fields first
    if (!Objects.equals(this.emplId, emp.emplId)) return false;

    // field comparison
    return Objects.equals(firstName, emp.firstName)
            && Objects.equals(lastName, emp.lastName);
}

Earn bitcoins upto $250 (free), invest in other Cryptocurrencies when you signup with blockfi. Use the referral link: Signup now and earn!

Using BlockFi, don't just buy crypto - start earning on it. Open an interest account with up to 8.6% APY, trade currencies, or borrow money without selling your assets.

Join CoinBase! We'll both receive $10 in free Bitcoin when they buy or sell their first $100 on Coinbase! Available in India also. Use the referral Join coinbase!

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.