4.5方法参数

java程序设计语言对对象的蚕蛹不是引用调用，实际上，对象引用进行的是值传递

java程序设计语言中方法参数的使用情况：

1.一个方法不能修改一个基本数据类型的参数。

2.一个方法可以改变一个对象参数的状态。

3.一个方法不能让对象参数引用一个新个的对象。

package com.qiao;

public class Demo2 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("Testing tripleValue:");
		double percent =10;
		System.out.println("Before :percent= "+percent);
		tripleValue(percent);
		System.out.println("After :percent="+percent);
		/*testing 2*/
		System.out.println("\nTesting tripleSalary:");
		Employee harry =new Employee("Harry", 50000);
		System.out.println("Before salary="+harry.getSalary());
		tripleSalary(harry);
		System.out.println("After:salary="+harry.getSalary());
		
		/*testing 3*/
		System.out.println("\nTesting swap:");
		Employee a = new Employee("Alice", 70000);
		Employee b =new Employee("Bob", 60000);
		System.out.println("Before : a="+a.getName());
		System.out.println("Before: b ="+b.getName());
		swap(a, b);
		System.out.println("After: a="+a.getName());
		System.out.println("After: b="+b.getName());
		
		
	}
	public static void tripleValue(double x)
	{
		x = 3 * x;
		System.out.println("End od method:x="+x);
	}
	
	public static void tripleSalary(Employee x)
	{
		x.raiseSalary(200);
		System.out.println("End of method:salary="+x.getSalary());
	}
	
	public static void swap(Employee x,Employee y)
	{
		Employee temp =x;
		x =y;
		y = temp;
		System.out.println("End of method:x="+x.getName());
		System.out.println("End of method:y="+y.getName());
	}

}

class Employee
{
	private String name;
	private	double salary;
	
	public Employee(String n,double s)
	{
		name = n;
		salary = s;
	}
	public String getName()
	{
		return name;
	}
	 public double getSalary()
	 {
		 return salary;
	 }
	 
	 public void raiseSalary(double byPercent)
	 {
		 salary += salary * byPercent/100;
	 }
}