Java 中的值传递和引用传递问题

Java 中的值传递和引用传递问题

public class Operation {
    int data = 50;

    void change(int data) {
        data = data + 100;
    }

    public static void main(String[] args) {
        Operation op = new Operation();
        System.out.println("before change: " + op.data);
        op.change(200);
        System.out.println("after change: " + op.data);
    }
}

点击查看结果

```
before change: 50
after change: 50
```

public class Operation2 {
    int data = 50;

    void change(Operation2 op) {
        op.data = op.data + 100;
    }

    public static void main(String args[]) {
        Operation2 op = new Operation2();
        System.out.println("before change " + op.data);
        op.change(op);
        System.out.println("after change " + op.data);
    }
}

点击查看结果

```
before change 50
after change 150
```

Dog 类

```
public class Dog {
String name;

Dog(String name) {
    this.name = name;
}

String getName() {
    return this.name;
}

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

String getObjectAddress() {
    return super.toString();
}

}

</div>

```java
public class PassByValueExample {
    public static void main(String[] args) {
        Dog dog = new Dog("A");
        System.out.println(dog.getObjectAddress());
        System.out.println("------------------------");
        func(dog);
        System.out.println("------------------------");
        System.out.println(dog.getObjectAddress());
        System.out.println(dog.getName());
    }

    private static void func(Dog dog) {
        System.out.println(dog.getObjectAddress());
        dog = new Dog("B");
        System.out.println(dog.getObjectAddress());
        System.out.println(dog.getName());
    }
}

点击查看结果

```
Dog@1b6d3586
------------------------
Dog@1b6d3586
Dog@4554617c
B
------------------------
Dog@1b6d3586
A

Process finished with exit code 0

</div>

```java
public class PassByValueExample2 {
    public static void main(String[] args) {
        Dog dog = new Dog("A");
        func(dog);
        System.out.println(dog.getName());
    }

    private static void func(Dog dog) {
        dog.setName("B");
    }
}

点击查看结果

```
B
```

posted @
2018-12-09 21:21 
走在修行的大街上 
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