public class ByValueOrByReference
{
  public static void main(String []args)
  {
    Person p1=new Person("Zhangsan");
    Person p2=new Person("Lisi");
    swap(p1,p2);
    System.out.println("p1 name: "+p1.getName()+"\np2 nam e: "+p2.getName());//p1 name: Zhangsan
                                //p2 name: Lisi    
    //象是by value;
    changeName(p1,p2);
    System.out.println("p1 name: "+p1.getName()+"\np2 name: "+p2.getName());//p1 name: Lisi
                               //p2 name: Zhangsan
                               //象是by reference;
  }
  public static void swap(Person p1,Person p2)
  {
    Person temp=p1;
    p1=p2;
    p2=temp;
  }
  public static void changeName(Person p1,Person p2)
  {
    p1.setName("Lisi");
    p2.setName("Zhangsan");
  }
} 
class Person
{
  private String name;
  public Person(String name)
  {
  this.name=name;
  }
  public String getName()
  {
  return name;
  }
  public void setName(String name)
  {
  this.name=name;
  }
  
}