public class Main {

    public static void main(String[] args) {
        System.out.println("Hello World!");

        //Test1
        System.out.println("Test1");
        double percent = 10;
        System.out.println("befor percent=" + percent);
        tripleValue(percent);
        System.out.println("After percent" + percent);

        //Text2
        System.out.println("Text2");
        Employee harry = new Employee("Harry", 500);
        System.out.println("befor salary" + harry.getSalary());
        tripleSalary1(harry);
        System.out.println("After salary" + harry.getSalary());

        System.out.println("Text3");
        Employee harry2 = new Employee("Harry", 500);
        System.out.println("befor salary" + harry2.getSalary());
        tripleSalary2(harry2);
        System.out.println("After salary" + harry2.getSalary());

        //Text4
        System.out.println("Test4");
        System.out.println("\nTest4:");
        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=x*3;
        System.out.println("End of method x=" + x);
    }

    public static void tripleSalary1(Employee x) {
        x.raiseSalary(200);
        System.out.println("End of method: salary=" + x.getSalary());

    }
    public static void tripleSalary2(Employee x) {
        double a=x.getSalary();
        a=a*3;
        x.setSalary(a);
        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 name, double salary) {
        this.name = name;
        this.salary = salary;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public void raiseSalary(double byPercent) {
        double raise=salary*byPercent/100;
        salary=raise;
    }
}

運(yùn)行結(jié)果

Hello World!
Test1
befor percent=10.0
End of method x=30.0
After percent10.0
Text2
befor salary500.0
End of method: salary=1000.0
After salary1000.0
Text3
befor salary500.0
End of method: salary=1500.0
After salary1500.0
Test4

Test4:
Before: a=Alice
Before: b=Bob
End of method: x=Bob
End of method: y=Alice
After: a=Alice
After: b=Bob

在這個(gè)程序中赂蠢， 首先試圖將一個(gè)值參數(shù)的值
提高兩倍望伦，但沒(méi)有成功：

Testing tripleValue:
Before: percent=10.0
End of method: x:30.0
After: percent=10.0

隨后秫逝， 成功地將一個(gè)雇員的薪金提高了兩倍：

Testing tripleSalary:
Before: salary=50000.0
End of method: salary=150000.0
After: salary=150000.0

方法結(jié)束之后贺辰， harry 引用的對(duì)象狀態(tài)發(fā)生了改變户盯。這是因?yàn)檫@個(gè)方法可以通過(guò)對(duì)象引用
的拷貝修改所引用的對(duì)象狀態(tài)。
最后饲化，程序演示了 swap 方法的失敗效果：

Testing swap:
Before: a=Alice
Before: b=Bob
End of method: x=Bob
End of method: y=Alice
After: a=Alice
After: b=Bob

可以看出莽鸭， 參數(shù)變量 X 和 y 交換了， 但是變量 a 和 b 沒(méi)有受到影響吃靠。

圖示.jpg