JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS


Program: How to sort ArrayList using Comparator?


Description:

This example gives you how to sort an ArrayList using Comparator. The ArrayList contains user defined objects. By using Collections.sort() method you can sort the ArrayList. You have to pass Comparator object which contains your sort logic. The example sorts the Empl objects based on highest salary.


Code:
package com.java2novice.arraylist;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class MyArrayListSort {
	
	public static void main(String a[]){
		
		List<Empl> list = new ArrayList<Empl>();
		list.add(new Empl("Ram",3000));
		list.add(new Empl("John",6000));
		list.add(new Empl("Crish",2000));
		list.add(new Empl("Tom",2400));
		Collections.sort(list,new MySalaryComp());
		System.out.println("Sorted list entries: ");
		for(Empl e:list){
			System.out.println(e);
		}
	}
}

class MySalaryComp implements Comparator<Empl>{

	@Override
	public int compare(Empl e1, Empl e2) {
		if(e1.getSalary() < e2.getSalary()){
			return 1;
		} else {
			return -1;
		}
	}
}

class Empl{
	
	private String name;
	private int salary;
	
	public Empl(String n, int s){
		this.name = n;
		this.salary = s;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
	public String toString(){
		return "Name: "+this.name+"-- Salary: "+this.salary;
	}
}

Output:
Sorted list entries: 
Name: John-- Salary: 6000
Name: Ram-- Salary: 3000
Name: Tom-- Salary: 2400
Name: Crish-- Salary: 2000
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List Of All ArrayList Sample Programs:

  1. Basic ArrayList Operations.
  2. How to read all elements in ArrayList by using iterator?
  3. How to copy or clone a ArrayList?
  4. How to add all elements of a list to ArrayList?
  5. How to delete all elements from my ArrayList?
  6. How to find does ArrayList contains all list elements or not?
  7. How to copy ArrayList to array?
  8. How to get sub list from ArrayList?
  9. How to sort ArrayList using Comparator?
  10. How to reverse ArrayList content?
  11. How to shuffle elements in ArrayList?
  12. How to swap two elements in a ArrayList?
  13. How to convert list to csv string format?
Knowledge Center
Difference between Enumeration and Iterator
The functionality of Enumeration and the Iterator are same. You can get remove() from Iterator to remove an element, while while Enumeration does not have remove() method. Using Enumeration you can only traverse and fetch the objects, where as using Iterator we can also add and remove the objects. So Iterator can be useful if you want to manipulate the list and Enumeration is for read-only access.

About Author

My name is Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me at java2novice@gmail.com or you can comment on the page.

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Reference: Java™ Platform Standard Ed. 6 - API Specification | Java is registered trademark of Oracle.
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