Java pass by value

 package examples;  
 public class PrimativeDataToMethod {  
      public static void main(String[] args) {  
           // primitive data to method  
           int num1 = 10;  
           int num2 = 20;  
           PriCheck pri = new PriCheck();  
           pri.swap(num1, num2);  
           System.out.println("Outside method dont swap" + num1 + '\t' + num2);  
 System.out.println("");  
           // Object to method  
           Employee E1 = new Employee(100);  
           Employee E2 = new Employee(200);  
           System.out.println("BEFORE "+"E1 " + E1.empId + '\t' + "E2 " + E2.empId);  
           // call the swap method  
           SwpEmpID swap = new SwpEmpID();  
           swap.swap(E1, E2);  
           System.out  
                     .println("AFTER " + "E1 " + E1.empId + '\t' + "E2 " + E2.empId);  
      }  
 }  
 // passing primitive data to method  
 class PriCheck {  
      // swap num1 and num2 within method  
      public void swap(int num1, int num2) {  
           int tmp;  
           tmp = num1;  
           num1 = num2;  
           num2 = tmp;  
           System.out.println("within method swap " + num1 + '\t' + num2);  
      }  
 }  
 // create a employee class  
 class Employee {  
      int empId;  
      public Employee(int empId) {  
           this.empId = empId;  
      }  
 }  
 // passing object to method  
 class SwpEmpID {  
      public void swap(Employee E1, Employee E2) // passing Employee object to  
                                                             // method to swap object  
      {  
           Employee tmp;  
           tmp = E1;  
           E1 = E2;  
           E2 = tmp;  
           // access instance variable of Object E1 and E2 within method  
           System.out.println("instance variable of Object E1 and E2 WITHIN method "  
                     + E1.empId+'\t'+E2.empId);  
      }  
 }