实体作为参数传递，到底是值传递还是引用传递

实体直接作为参数传递，最后实体参数的属性值也会改变

1.新建一个Student实体类

public class Student {
    private String name;
    private Integer age;

    public Student() {
    }

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + ''' +
                ", age=" + age +
                '}';
    }
}

2.新建一个测试类

public class Test {
    public static void main(String[] args) throws CloneNotSupportedException {
        Student stua  =  new Student("zhangsan",15);
        System.out.println("stua---->"+stua);
        Student stub = new Student();
        //将实体参数直接复制给b,并传递
        stub = stua;
        ageAdd(stub);
        System.out.println("==================");
        System.out.println("stua---->"+stua);
    }

    public static void ageAdd(Student stub) throws CloneNotSupportedException {
        stub.setAge(stub.getAge()+1);
        System.out.println("stub---->"+stub);
    }
}

3.得出结果，改变了实参的属性值

解决方法：只需要在实体类实现Cloneable接口，并且重写clone方法

实体类变为：

public class Student implements Cloneable {
    private String name;
    private Integer age;

    public Student() {
    }

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + ''' +
                ", age=" + age +
                '}';
    }

    /**
     * 记得重写克隆方法
     * @return
     * @throws CloneNotSupportedException
     */
    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

测试类为：

public class Test {
    public static void main(String[] args) throws CloneNotSupportedException {
        Student stua  =  new Student("zhangsan",15);
        System.out.println("stua---->"+stua);
        Student stub = new Student();
        //将实体参数的值克隆一份并传递
        stub = (Student) stua.clone();
        ageAdd(stub);
        System.out.println("==================");
        System.out.println("stua---->"+stua);
    }

    public static void ageAdd(Student stub) throws CloneNotSupportedException {
        stub.setAge(stub.getAge()+1);
        System.out.println("stub---->"+stub);
    }
}

测试结果：

**

最后有个疑问：java不是不涉及引用传递吗？这里为什么会改变原来对象的值呢？

**

最后

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