菜鸟求助，Java中传值还是传引用？
请解释一下，为什么tripleSalary(harry)使得harry的工资是原来的3倍，
而在执行完swap(a,b)函数后并没有使原先指向Alice的a指向Bob呢？

public class ParamTest
{
public static void main(String[] args)
{
Employee harry = new Employee("Harry", 50000);
System.out.println("Before: salary=" + harry.getSalary());
tripleSalary(harry);
System.out.println("After: salary=" + harry.getSalary());

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 tripleSalary(Employee x) // works
{
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 // simplified Employee class
{
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)
{
double raise = salary * byPercent / 100;
salary += raise;
}

private String name;
private double salary;
}


[解决办法]


看到了吗，x,y的指向改变了
但不会改变a,b的指向，
a,b还是指向了原来的对象。

遇到这种传值的问题最好画个内存图，
很明了清晰，不要看着程序想。

java中只有值传递，引用传递本质上也是值传递
叫法不同是为了区分传的是值还是引用

至于工资三倍的问题，楼主仔细看看题就知道了
raise = salary * byPercent / 100;
salary += raise;
==>
salary += salary * byPercent / 100;(byPercent传的是200)
==>
salary = salary + salary * byPercent / 100;
==>
salary = salary * (1 + 2)