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Guava: Useful Objects class


In Effective Java Book, Joshua Bloch advocate about the overriding the methods which are common to all Objects

Some common methods are
  • hasCode
  • equals
  • compareTo
  • toString

Overriding the method are good but overriding correctly is must else it will create unwanted errors.
Here Guava Objects class comes very handy

public class User implements Comparable<User>{
    public String firstName;
    public String lastName;
    public String userId;
    public String emailId;
    public Date dateOfBirth;
    public boolean active;
    
    @Override
    public int hashCode() {
        return Objects.hashCode(firstName,
        lastName,
        emailId,
        userId,
        dateOfBirth,
        active);
    }
    
    @Override
    public boolean equals(Object obj) {
        if(obj instanceof User){
            User that = (User)obj;
            return Objects.equal(this.firstName, that.firstName) &&
            Objects.equal(this.lastName, that.lastName) &&
            Objects.equal(this.userId, that.userId) &&
            Objects.equal(this.emailId, that.emailId) &&
            Objects.equal(this.dateOfBirth, that.dateOfBirth) &&
            Objects.equal(this.active, that.active);
        }
        return false;
    }
    
    @Override
    public int compareTo(final User user) {
        return ComparisonChain.start()
        .compare(this.firstName, user.firstName)
        .compare(this.lastName, user.lastName)
        .compare(this.userId, user.userId)
        .compare(this.emailId, user.emailId)
        .compare(this.dateOfBirth, user.dateOfBirth)
        .compare(this.active, user.active)
        .result();
    }
    
    @Override
    public String toString() {
        return Objects.toStringHelper(this)
        .add("firstName", this.firstName)
        .add("lastName", this.lastName)
        .add("userId", this.userId)
        .toString();
    }
    
}

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