关于java中的值传递与引用传递

Dear 丶 2022-05-22 09:28 162阅读 0赞

结论：

1. 对于值传递，如int, long等基本类型，不管传入方法后怎么修改，都改变不了方法外面的值。

2. 对于引用传递，如果传入方法后指向了一个新的对象，那么无论怎么修改也改变不了方法外面的对象。

如果传入方法后没有指向新对象，直接操作，就会改变方法外面的对象，因为这是在操作同一个对象。

**结论下完直接上干货代码：**

public class DeliveryTest {
    
        private String name;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public static void changeInt(int num){
            num = 20;
        }
        public static void changeString(String string){
            string = "string";
        }
        public static void changeNewString(String string){
            string = new String("bbb");
    
        }
        public static void changeObject(DeliveryTest object){
            object.setName("lisi");
    
        }
        public static void changeNewObject(DeliveryTest object){
            object = new DeliveryTest();
            object.setName("lisi");
    
        }
    
        public static void main(String[] args) {
    
            int num = 10;
            System.out.println(num);
            DeliveryTest.changeInt(num);
            System.out.println(num);
            System.out.println("===============================");
    
            String str = "str";
            System.out.println(str);
            DeliveryTest.changeString(str);
            System.out.println(str);
            System.out.println("===============================");
    
            String string = "aaa";
            System.out.println(string);
            DeliveryTest.changeNewString(string);
            System.out.println(string);
            System.out.println("===============================");
    
            DeliveryTest deliveryTest = new DeliveryTest();
            deliveryTest.setName("zhangsan");
            System.out.println(deliveryTest.getName());
            DeliveryTest.changeObject(deliveryTest);
            System.out.println(deliveryTest.getName());
            System.out.println("===============================");
    
            DeliveryTest dt = new DeliveryTest();
            deliveryTest.setName("zhangsan");
            System.out.println(deliveryTest.getName());
            DeliveryTest.changeNewObject(dt);
            System.out.println(deliveryTest.getName());
            
    
        }
    }

**执行完结果：**

**![70][]**

[70]: /images/20220522/4127d1d8e426495080b7a97fd0da9ddd.png