JAVA学习笔记(七)- 值传递与引用传递

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值传递与引用传递概念

值传递：在方法进行调用时，形式参数是由实际参数来传递的，方法执行中形式参数值的改变不影响实际参数的值。引用传递：就是地址传递。在方法进行调用时，实际参数的引用的是地址，而不是真正参数的值，方法执行中形式参数值的改变将会影响实际参数的值。

代码实例

public class Student{    public int age;}

public class Tool{    public void swap(int a, int b)    {        int temp = a;        a = b;        b = temp;        System.out.println("值传递-方法内，交换后的值  " + "a = " + a + "  b = " + b);    }    public void swap(Student s1, Student s2)    {        int temp = s1.age;        s1.age = s2.age;        s2.age = temp;        System.out.println("引用传递-方法内，交换后的值  " + "s1 = " + s1.age + "  s2 = " + s2.age);    }    public void swap1(Student s1, Student s2)    {        Student ss = new Student();        ss = s1;        s1 = s2;        s2 = ss;        System.out.println("引用传递-方法内，交换后的值  " + "s1 = " + s1.age + "  s2 = " + s2.age);    }}

public class Test{    public static void main(String[] args)    {        Tool tool = new Tool();        //1-值传递        int x = 10;        int y = 20;        tool.swap(x, y);//a = x; b = y;        System.out.println("main 交换后 " + "x = " + x + "  y = " + y);        //2-引用传递        Student s1 = new Student();        s1.age = 15;        Student s2 = new Student();        s2.age = 51;        tool.swap(s1, s2);//s1 = s1; s2 = s2;        System.out.println("main 交换后  " + "s1 = " + s1.age + "  s2 = " + s2.age);        tool.swap1(s1, s2);//s1 = s1; s2 = s2;    }}

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