您可以通过Java的引用传递？ [英] Can you pass by reference in Java?

问题描述

很抱歉，如果这听起来像一个新手的问​​题，但有一天，一个Java开发者引用传递一个放慢参数（由它被换货只是传递一个参考对象）

Sorry if this sounds like a newbie question, but the other day a Java developer mentioned about passing a paramter by reference (by which it was ment just pass a Reference object)

从C＃的角度来看，我可以通过值或引用传递引用类型，这也是千真万确的值类型

From a C# perspective I can pass a reference type by value or by reference, this is also true to value types

我已经写了noddie控制台应用程序，以显示我的意思..我可以做到这一点在Java中？

I have written a noddie console application to show what i mean.. can i do this in Java?

namespace ByRefByVal
{
    class Program
    {
        static void Main(string[] args)
        {
            //Creating of the object
            Person p1 = new Person();
            p1.Name = "Dave";
            PrintIfObjectIsNull(p1); //should not be null

            //A copy of the Reference is made and sent to the method
            PrintUserNameByValue(p1);
            PrintIfObjectIsNull(p1);

            //the actual reference is passed to the method
            PrintUserNameByRef(ref p1);    //<-- I know im passing the Reference
            PrintIfObjectIsNull(p1);

            Console.ReadLine();
        }

        private static void PrintIfObjectIsNull(Object o)
        {
            if (o == null)
            {
                Console.WriteLine("object is null");
            }
            else
            {
                Console.WriteLine("object still references something");
            }
        }

        /// <summary>
        /// this takes in a Reference type of Person, by value
        /// </summary>
        /// <param name="person"></param>
        private static void PrintUserNameByValue(Person person)
        {
            Console.WriteLine(person.Name);
            person = null; //<- this cannot affect the orginal reference, as it was passed in by value.
        }

        /// <summary>
        /// this takes in a Reference type of Person, by reference
        /// </summary>
        /// <param name="person"></param>
        private static void PrintUserNameByRef(ref Person person)
        {
            Console.WriteLine(person.Name);
            person = null; //this has access to the orginonal reference, allowing us to alter it, either make it point to a different object or to nothing.
        }


    }

    class Person
    {
        public string Name { get; set; }
    }
}

如果它Java可以不这样做，那么它只是按值传递一个引用类型？ （是公平地说）

If it java cannot do this, then its just passing a reference type by value? (is that fair to say)

非常感谢

骨

推荐答案

没有，爪哇不能做到这一点。 Java的只有按值传递。它通过值太大传递引用。

No, Java cannot do this. Java only passes by value. It passes references by value too.

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