Java是值传递（没有引用传递）！！！-蒲公英云

Java是值传递（没有引用传递）！！！

很多程序设计语言（特别是，C++和Pascal）提供了两种参数传递的方式：值调用和引用调用。有些程序员认为Java程序设计语言对对象采用的是引用调用，实际上，这种理解是不对的。由于这种误解具有一定的普遍性，所以下面给出一个反例来详细地阐述一下这个问题。

请问下面的employee1和employee2交换引用地址了吗？

public static void main(String[] args) { 
        Employee employee1 = new Employee("张三",1500);
        Employee employee2 = new Employee("李四",2000);
        System.out.printf("初始：employee1：%s,employee2：%s",employee1,employee2);
        swap(employee1, employee2);
        System.out.println();
        System.out.printf("swap后：employee1：%s,employee2：%s",employee1,employee2);
    }
    public static void swap(Employee e1, Employee e2) { 
        Employee temp = e1;
        e1 = e2;
        e2 = temp;
    }

完整代码如下：

package com.demo.test.demo.api;
/** * 探究Java究竟是值传递还是引用传递 * * @author zhao.hualuo * Create at 2021/8/9 */
public class ParameterDemo { 
    public static void main(String[] args) { 
        Employee employee1 = new Employee("张三",1500);
        Employee employee2 = new Employee("李四",2000);
        System.out.printf("初始：employee1：%s,employee2：%s",employee1,employee2);
        swap(employee1, employee2);
        System.out.println();
        System.out.printf("swap后：employee1：%s,employee2：%s",employee1,employee2);
    }
    public static void swap(Employee e1, Employee e2) { 
        Employee temp = e1;
        e1 = e2;
        e2 = temp;
    }
    /** * 雇员类 */
    static class Employee { 
        /** 姓名 */
        private String name;
        /** 薪水 */
        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;
        }
    }
}

执行结果如下：

在这里插入图片描述
由于java不是引用传递，所以上面的e1并不是employee1。
e1只是employee1 copy出来的一个引用，这两个引用指向同一个地址，但是这俩并不是一个引用。所以可以说e1和e2互换了引用地址，但是不能说employee1和employee2交换了地址。

下面是验证代码：

package com.demo.test.demo.api;
/** * 探究Java究竟是值传递还是引用传递 * * @author zhao.hualuo * Create at 2021/8/9 */
public class ParameterDemo { 
    public static void main(String[] args) { 
        Employee employee1 = new Employee("张三",1500);
        Employee employee2 = new Employee("李四",2000);
        System.out.printf("外面：employee1：%s,employee2：%s",employee1,employee2);
        System.out.println();
        swap(employee1, employee2);
        System.out.println();
        System.out.printf("外面：employee1：%s,employee2：%s",employee1,employee2);
    }
    public static void swap(Employee e1, Employee e2) { 
        System.out.printf("初始：e1：%s,e2：%s",e1,e2);
        Employee temp = e1;
        e1 = e2;
        e2 = temp;
        System.out.println();
        System.out.printf("最后：e1：%s,e2：%s",e1,e2);
    }
    /** * 雇员类 */
    static class Employee { 
        /** 姓名 */
        private String name;
        /** 薪水 */
        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;
        }
    }
}