Java 引用传递

public class Main {
    public static void main(String[] args) {
        Employee worker=new Employee("张三");
        Employee manager=new Employee("李四");
        swap(worker,manager);
        System.out.println(worker.name+" "+manager.name);  
    }
}
  class Employee {

    public String name=null;

    public Employee(String n){
        this.name=n;
    }
    //将两个Employee对象交换
    public static void swap(Employee e1,Employee e2){
        Employee temp=e1;
        e1=e2;
        e2=temp;
        System.out.println(e1.name+" "+e2.name); 
    }
}

public class Main {
    public static void main(String[] args) {
        // 建立并构造两个对象
        Person p1 = new Person("Alexia", "female");
        Person p2 = new Person("Edward", "male");

        System.out.println("对象交换前：p1 = " + p1.toString());
        System.out.println("对象交换前：p2 = " + p2.toString());

        // 交换p1对象和p2对象
        Person.swapObject(p1, p2);
        // 从交换结果中看出，实际对象并未交换
        System.out.println("\n对象交换后：p1 = " + p1.toString());
        System.out.println("对象交换后：p2 = " + p2.toString());

        // 建立两个对象数组
        Person[] arraya = new Person[2];
        Person[] arrayb = new Person[2];

        // 分别构造数组对象
        arraya[0] = new Person("Alexia", "female");
        arraya[1] = new Person("Edward", "male");
        arrayb[0] = new Person("jmwang", "female");
        arrayb[1] = new Person("hwu", "male");

        System.out.println(‘\n‘ + "对象数组交换前：arraya[0] = "
                + arraya[0].toString() + ", arraya[1] = "
                + arraya[1].toString());
        System.out.println("对象数组交换前：arrayb[0] = "
                + arrayb[0].toString() + ", arrayb[1] = "
                + arrayb[1].toString());

        // 交换这两个对象数组
        Person.swapObjectArray(arraya, arrayb);
        System.out.println(‘\n‘ + "对象数组交换后：arraya[0] = "
                + arraya[0].toString() + ", arraya[1] = "
                + arraya[1].toString());
        System.out.println("对象数组交换后：arrayb[0] = "
                + arrayb[0].toString() + ", arrayb[1] = "
                + arrayb[1].toString());

        // 建立两个普通数组
        int[] a = new int[2];
        int[] b = new int[2];

        // 给数组个元素赋值
        for (int i = 0; i < a.length; i++) {
            a[i] = i;
            b[i] = i + 1;
        }

        System.out.println(‘\n‘ + "基本类型数组交换前：a[0] = " + a[0] + ", a[1] = " + a[1]);
        System.out.println("基本类型数组交换前：b[0] = " + b[0] + ", b[1] = " + b[1]);

        // 交换两个基本类型数组
        Person.swapIntArray(a, b);
        System.out.println(‘\n‘ + "基本类型数组交换后：a[0] = " + a[0] + ", a[1] = " + a[1]);
        System.out.println("基本类型数组交换后：b[0] = " + b[0] + ", b[1] = " + b[1]);

        // 改变对象数组的内容
        Person.changeObjectArray(arraya, arrayb);
        System.out.println(‘\n‘ + "对象数组内容交换并改变后：arraya[1] = " + arraya[1].toString());
        System.out.println("对象数组内容交换并改变后：arrayb[1] = " + arrayb[1].toString());

        // 改变基本类型数组的内容
        Person.changeIntArray(a, b);
        System.out.println(‘\n‘ + "基本类型数组内容交换并改变后：a[1] = " + a[1]);
        System.out.println("基本类型数组内容交换并改变后：b[1] = " + b[1]);
    }
}

class Person {

    private String name;

    private String sex;

    public Person(String x, String y) {
        this.name = x;
        this.sex = y;
    }

    // 重写toString()方法，方便输出
    public String toString() {

        return name + " " + sex;
    }

    // 交换对象引用
    public static void swapObject(Person p1, Person p2) {
        Person tmp = p1;
        p1 = p2;
        p2 = tmp;
    }

    // 交换基本类型
    public static void swapInt(int a, int b) {
        int tmp = a;
        a = b;
        b = tmp;
    }

    // 交换对象数组
    public static void swapObjectArray(Person[] p1, Person[] p2) {
        Person[] tmp = p1;
        p1 = p2;
        p2 = tmp;
    }

    // 交换基本类型数组
    public static void swapIntArray(int[] x, int[] y) {
        int[] tmp = x;
        x = y;
        y = tmp;
    }

    // 改变对象数组中的内容
    public static void changeObjectArray(Person[] p1, Person[] p2) {
        Person tmp = p1[1];
        p1[1] = p2[1];
        p2[1] = tmp;

        // 再将p1[1]修改
        Person p = new Person("wjl", "male");
        p1[1] = p;
    }

    // 改变基本类型数组中的内容
    public static void changeIntArray(int[] x, int[] y) {
        int tmp = x[1];
        x[1] = y[1];
        y[1] = tmp;

        x[1] = 5;
    }
}