Sort Employee Object Saved in ArrayList Based On Condition

Few employee objects are saved in arraylist. Will try to sort these element either by Employee name or Employee salary. I have created 2 java files: Employee.java, SortEmployee.java in same package.

package com.chetasmind.listPackage;

public class Employee {
    
    private int empID;
    private String empName;
    private double empSalary;
     
    public Employee() {
         
    }
    public Employee(int empID,String empName,double empSalary) {
        this.empID = empID;
        this.empName = empName;
        this.empSalary = empSalary;
    }
     
    public int getEmpID() {
        return empID;
    }
    public void setEmpID(int empID) {
        this.empID = empID;
    }
    public String getEmpName() {
        return empName;
    }
    public void setEmpName(String empName) {
        this.empName = empName;
    }
    public double getEmpSalary() {
        return empSalary;
    }
    public void setEmpSalary(double empSalary) {
        this.empSalary = empSalary;
    }
     
    @Override
    public String toString() {
         
        String empDetails = "Employee ID: "+this.empID+" Employee Name: "+this.empName+" Salary="+this.empSalary; 
        return empDetails;
         
    }
}

package com.chetasmind.listPackage;

import java.util.ArrayList;
import java.util.Comparator;
 
class SalaryComparator implements Comparator<Employee>{
 
    @Override
    public int compare(Employee o1, Employee o2) {
         
        if(o1.getEmpSalary() > o2.getEmpSalary())
            return 1;
        else if(o1.getEmpSalary() < o2.getEmpSalary())
            return -1;
        else
            return 0;
    }
}
class NameComparator implements Comparator<Employee>{
 
    @Override
    public int compare(Employee o1, Employee o2) {
        return o1.getEmpName().compareTo(o2.getEmpName());
    }
}
 
public class SortEmployee {
 
    public static void main(String[] args) {
         
        ArrayList<Employee>obj = new ArrayList<>();
         
        Employee emp1 = new Employee(101,"Sagar",45000);
        Employee emp2 = new Employee(102,"Rekha",85000);
        Employee emp3 = new Employee(103,"Suhas",35000);
        Employee emp4 = new Employee(104,"Kavya",80000);
          
        obj.add(emp1);
        obj.add(emp2);
        obj.add(emp3);
        obj.add(emp4);
         
        System.out.println("Displaying Arraylist element before sorting");
        for(int i=0;i<obj.size();i++) {
            System.out.println(obj.get(i));
        }
         
        String compareUsing = "salary";
         
        if(compareUsing.equals("salary"))
            obj.sort(new SalaryComparator());
        else
            obj.sort(new NameComparator());
         
        System.out.println("Displaying Arraylist element after sorting");
        for(int i=0;i<obj.size();i++) {
            System.out.println(obj.get(i));
        }
    }
}

SalaryComparator class implements Comparator interface. So, you must write compare method. This compare method accepts 2 Employee object: Employee o1, Employee o2. This method compares these object based on salary and passes the integer value. Same case with NameComparator class. This compares the employee name.

In line no: 48, i have created a String literal compareUsing = “salary”; You can change this value to compare using name. Output of above code is as shown below.

Displaying Arraylist element before sorting
Employee ID: 101 Employee Name: Sagar Salary=45000.0
Employee ID: 102 Employee Name: Rekha Salary=85000.0
Employee ID: 103 Employee Name: Suhas Salary=35000.0
Employee ID: 104 Employee Name: Kavya Salary=80000.0
Displaying Arraylist element after sorting
Employee ID: 103 Employee Name: Suhas Salary=35000.0
Employee ID: 101 Employee Name: Sagar Salary=45000.0
Employee ID: 104 Employee Name: Kavya Salary=80000.0
Employee ID: 102 Employee Name: Rekha Salary=85000.0

The above application is also present in my github repository.
If you are writing java applications for the first time, refer my Project structure article.