How to swap or exchange objects in Java?

Wrapper Class can be used to swap or exchange objects in Java.

A Java program using wrapper classes to swap objects.

class Employee
{
    int empno, salary;
    Car(int empno, int salary)  //Parameterized constructor
    {
        this.empno = empno;
        this.salary = salary;
    }

    void print()    //Method printing Employee details
    {
        System.out.println("Employee No. = " + empno +   ", salary = " + salary);
    }
}

// A Wrapper over class that is used for swapping

class EmployeeWrapper
{
   Employee e;
   EmployeeWrapper(Employee e)   
   {
    this.e = e;
   }
}

//A Class that use Employee and swaps objects of Employee using EmployeeWrapper

class Main
{
    // This method swaps Employee objects in wrappers ew1 and ew2

    public static void swap(EmployeeWrapper ew1, EmployeeWrapper ew2)
    {
        Employee temp = ew1.e;
        ew1.e = ew2.e;
        ew2.e = temp;
    }

    public static void main(String[] args)
    {
        Employee e1 = new Employee(1,1000);
        Employee e2 = new Employee(2, 2000);
        EmployeeWrapper ew1 = new EmployeeWrapper(e1);
        EmployeeWrapper ew2 = new EmployeeWrapper(e2);
        swap(cw1, cw2);
        ew1.e.print();
        ew2.e.print();
    }
}

Output:

Employee No. =2,salary =1000
Employee No. =1,salary =2000

Explanation of above program:

In this a wrapper class that contains references of Employee is created. Swapping references of wrapper class swaps Employee objects.So a wrapper class solution works even if the user class doesnt have access to members of the class whose objects are to be swapped.