Comparable vs Comparator in Java
Comparable
Create Person model class implements Comparable interface and compare with all of 3 age, name, salary fields like name for string, age for integer, and salary for double.
Person Model Class
public class Person implements Comparable<Person>{
String name;
int age;
double salary;
String city;
@Override
public String toString() {
return “Person [name=” + name + “, age=” + age + “, salary=” + salary + “, city=” + city + “]”;
}
public Person(String name,double salary, int age,String city) {
super();
this.name = name;
this.salary = salary;
this.age = age;
this.city = city;
}
public Person() {
super();
// TODO Auto-generated constructor stub
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
// Method for sorting object on the basis of age int value
/* public int compareTo(Person p) {
if(this.age==p.age)
{
return 0;
}
else if(this.age>p.age)
{
return 1;
}
else
{
return -1;
}
} */
// Method for sorting object on the basis of salary float value
/* public int compareTo(Person p) {
if(this.salary==p.salary)
{
return 0;
}
else if(this.salary>p.salary)
{
return 1;
}
else
{
return -1;
}
} */
// Method for sorting object on the basis of name String value
public int compareTo(Person p) {
return this.name.compareTo(p.getName());
}
}
TestComparable Class
package com.java.comparable;
import java.util.*;
public class TestComparable {
List<Person> li=new ArrayList<Person>();
TestComparable()
{
li.add(new Person(“zain”, 21323.34, 25, “KHI”));
li.add(new Person(“haris”, 61387.00, 31, “LHR”));
li.add(new Person(“adil”, 341.21, 28, “KHI”));
li.add(new Person(“faizan”, 8265.94, 29, “ISB”));
li.add(new Person(“raza”, 8235.42, 32, “KHI”));
li.add(new Person(“jaffar”, 8745.21, 31, “QTA”));
li.add(new Person(“hunain”, 5645.23, 24, “PES”));
}
public void display()
{
Collections.sort(li);
for(Person per:li)
{
System.out.println(per);
}
}
public static void main(String[] args)
{
new TestComparable().display();
}
}
Comparator
Create Person model class implements Comparator interface and compare with all of 3 age, name, salary fields like name for string, age for integer, and salary for double.
TestComparator Class
package com.java.comparator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import com.java.comparable.Person;
import com.java.comparable.TestComparable;
public class TestComparator {
List<Person> li=new ArrayList<Person>();
TestComparator()
{
li.add(new Person(“zain”, 21323.34, 25, “KHI”));
li.add(new Person(“haris”, 61387.00, 31, “LHR”));
li.add(new Person(“adil”, 341.21, 28, “KHI”));
li.add(new Person(“faizan”, 8265.94, 29, “ISB”));
li.add(new Person(“raza”, 8235.42, 32, “KHI”));
li.add(new Person(“jaffar”, 8745.21, 31, “QTA”));
li.add(new Person(“hunain”, 5645.23, 24, “PES”));
}
public void display()
{
// Anonymous object for sorting object on the basis of age int value
/* Collections.sort(li,new Comparator<Person>(){
public int compare(Person p1, Person p2) {
return p1.getAge()-p2.getAge();
}
}); */
// Anonymous object for sorting object on the basis of salary float value
/* Collections.sort(li,new Comparator<Person>(){
public int compare(Person p1, Person p2) {
return (int) (p1.getSalary()-p2.getSalary());
}
}); */
// Anonymous object for sorting object on the basis of name string value
Collections.sort(li,new Comparator<Person>(){
public int compare(Person p1, Person p2) {
return p1.getName().compareTo(p2.getName());
}
});
for(Person per:li)
{
System.out.println(per);
}
}
public static void main(String[] args)
{
new TestComparator().display();
}
}
