Java 值传递

public class Main {

    public static void main(String[] args) {
        String name = "muhuo";
        int age = 26;
        setName(name);
        setAge(age);
        System.out.println(name + " " + age);
    }
    private static void setName(String name) {
        name = "other name";
    }
    private static void setAge(int age) {
        age = 18;
    }
}

输出为：muhuo 26

以上证实基本无论是基本数据类型或者引用数据类型都是值传递，调用setName、setAge的参数都是参数的拷贝不影响其原始值

 

public class Main {

    private String name;

    private int age;

    public static void main(String[] args) {
        Main main = new Main("muhuo", 20);
        System.out.println(main);
    }

    private static void  mod(Main main) {
        main.name = "other name";
        main.age = 18;
    }

    public Main(String name, int age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        final StringBuffer sb = new StringBuffer("Main{");
        sb.append("name='").append(name).append('\'');
        sb.append(", age=").append(age);
        sb.append('}');
        return sb.toString();
    }
}

输出为：Main{name='muhuo', age=20}

所以对于对象来说，这里调用mod方法的参数是拷贝了mian对象的引用，但是这里引用所指向的真实地址是没变的，所以mod方法内部确实对原始对象中的值进行了改变。