package collection;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class HashCodeEqualsDemo {

    public static void main(String[] args) {


        // Add method of set will first check for hashcode, if method is not found, it
        // will create a new Object even if equals has been overridden
        // If hashcode has been overridden, and two employees have same id (thus same hashcode
        // as per our implementation), it will execute equals method, to find if two objects are equal.
        // For set to work properly for a custom reference type, it is mandatory to override both hashcode and equals
        Set<Employee> employeeSet = new HashSet<>();
        employeeSet.add(new Employee("ABC", "abc@gmail.com", 123));
        employeeSet.add(new Employee("ABC", "abc@gmail.com", 123));
        employeeSet.add(new Employee("XYZ", "abc@gmail.com", 100));
        employeeSet.add(new Employee("XYZ", "xyz@gmail.com", 123));
        System.out.println(employeeSet.size()); // 3


        //Add method of list will just check the equality using equals method. Following will work even if
        // hashcode has not been overridden.

        List<Employee> employeeList = new ArrayList<>();
        employeeList.add(new Employee("ABC", "abc@gmail.com", 123));
        employeeList.add(new Employee("ABC", "abc@gmail.com", 123));
        employeeList.add(new Employee("XYZ", "abc@gmail.com", 100));
        employeeList.add(new Employee("XYZ", "xyz@gmail.com", 123));
        System.out.println(employeeList.contains(new Employee("ABC", "abc@gmail.com", 123))); // true
        System.out.println(employeeList.contains(new Employee("PQR", "pqr@gmail.com", 500))); // false
        System.out.println(employeeList.contains(new Employee("PQR", "abc@gmail.com", 500))); // true

    }

}


class Employee {

    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    private int id;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    private String email;

    Employee(String name, String email, int id) {
        this.name = name;
        this.email = email;
        this.id = id;
    }

    @Override
    public boolean equals(Object object) {
        System.out.println("Equals called");
        if (this == object) {
            return true;
        }

        if (object == null || (this.getClass() != object.getClass()))
            return false;

        Employee employee = (Employee) object;
        return this.email.equals(employee.email);
    }

    @Override
    public int hashCode() {
        System.out.println("hashcode called");
        return this.id;
    }
}