java之值传递与地址传递

• 值传递
• 引用传递

//实例一:值传递
public class ValueDemo{
 public static void main(String[] args){
   int x = 10;
   System.out.println("x="+x);
  }
   public static void method(int mx){
	 mx = 20;
	}
}

值传递:是指在调用函数时将实际参数复制一份到函数中，这样在函数中如果对参数进行修改，将不会影响到实际参数。

public class RefDemo1{
  public static void main(String[] args){
    Duck d = new Duck();
    method(d);
    System.out.println("Duck age ="+d.age);
  }
  public static void method(Duck duck){
     duck.age = 5;
  }
}
class Duck{
 int  age = 2; //省略封装
}

对象的地址传递

字符串的地址传递
字符串本身就是一个对象

public class RefDemo2{
  String name = "小飞";
  method(name);
  System.out.println("name="+name);
  public static void method(String sname){
   sname = "小备";
 }
}

//示例四:String传递
public class RefDemo3{
 public static void main(String[] args){
     Person p = new Person();
     method(p);
     System.out.println("person name= "+p.name)
	}
	public static void method(Person per){
        per.name = "备备";
    }
}
class Person{
 String name = "飞飞";
}