Mega Code Archive
This program demonstrates the equals method
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/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.Date;
import java.util.GregorianCalendar;
/**
* This program demonstrates the equals method.
*
* @version 1.11 2004-02-21
* @author Cay Horstmann
*/
public class EqualsTest {
public static void main(String[] args) {
Employee alice1 = new Employee("Alice Adams", 75000, 1987, 12, 15);
Employee alice2 = alice1;
Employee alice3 = new Employee("Alice Adams", 75000, 1987, 12, 15);
Employee bob = new Employee("Bob Brandson", 50000, 1989, 10, 1);
System.out.println("alice1 == alice2: " + (alice1 == alice2));
System.out.println("alice1 == alice3: " + (alice1 == alice3));
System.out.println("alice1.equals(alice3): " + alice1.equals(alice3));
System.out.println("alice1.equals(bob): " + alice1.equals(bob));
System.out.println("bob.toString(): " + bob);
Manager carl = new Manager("Carl Cracker", 80000, 1987, 12, 15);
Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
boss.setBonus(5000);
System.out.println("boss.toString(): " + boss);
System.out.println("carl.equals(boss): " + carl.equals(boss));
System.out.println("alice1.hashCode(): " + alice1.hashCode());
System.out.println("alice3.hashCode(): " + alice3.hashCode());
System.out.println("bob.hashCode(): " + bob.hashCode());
System.out.println("carl.hashCode(): " + carl.hashCode());
}
}
class Employee {
public Employee(String n, double s, int year, int month, int day) {
name = n;
salary = s;
GregorianCalendar calendar = new GregorianCalendar(year, month - 1, day);
hireDay = calendar.getTime();
}
public String getName() {
return name;
}
public double getSalary() {
return salary;
}
public Date getHireDay() {
return hireDay;
}
public void raiseSalary(double byPercent) {
double raise = salary * byPercent / 100;
salary += raise;
}
public boolean equals(Object otherObject) {
// a quick test to see if the objects are identical
if (this == otherObject)
return true;
// must return false if the explicit parameter is null
if (otherObject == null)
return false;
// if the classes don't match, they can't be equal
if (getClass() != otherObject.getClass())
return false;
// now we know otherObject is a non-null Employee
Employee other = (Employee) otherObject;
// test whether the fields have identical values
return name.equals(other.name) && salary == other.salary && hireDay.equals(other.hireDay);
}
public int hashCode() {
return 7 * name.hashCode() + 11 * new Double(salary).hashCode() + 13 * hireDay.hashCode();
}
public String toString() {
return getClass().getName() + "[name=" + name + ",salary=" + salary + ",hireDay=" + hireDay
+ "]";
}
private String name;
private double salary;
private Date hireDay;
}
class Manager extends Employee {
public Manager(String n, double s, int year, int month, int day) {
super(n, s, year, month, day);
bonus = 0;
}
public double getSalary() {
double baseSalary = super.getSalary();
return baseSalary + bonus;
}
public void setBonus(double b) {
bonus = b;
}
public boolean equals(Object otherObject) {
if (!super.equals(otherObject))
return false;
Manager other = (Manager) otherObject;
// super.equals checked that this and other belong to the same class
return bonus == other.bonus;
}
public int hashCode() {
return super.hashCode() + 17 * new Double(bonus).hashCode();
}
public String toString() {
return super.toString() + "[bonus=" + bonus + "]";
}
private double bonus;
}
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