Java通过引用传递

编程入门行业动态更新时间:2024-10-28 18:30:34

本文介绍了Java通过引用传递的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！问题描述

这两个代码有什么区别：

What is the difference between this 2 codes:

代码A：

Foo myFoo; myFoo = createfoo();

其中

public Foo createFoo() { Foo foo = new Foo(); return foo; }

Vs。代码B：

Foo myFoo; createFoo(myFoo); public void createFoo(Foo foo) { Foo f = new Foo(); foo = f; }

这2个代码之间是否有任何差异？

Are there any differences between these 2 pieces of codes?

推荐答案

Java总是按值而不是通过引用传递参数。

Java always passes arguments by value NOT by reference.

让我通过示例解释一下：

public class Main { public static void main(String[] args) { Foo f = new Foo("f"); changeReference(f); // It won't change the reference! modifyReference(f); // It will modify the object that the reference variable "f" refers to! } public static void changeReference(Foo a) { Foo b = new Foo("b"); a = b; } public static void modifyReference(Foo c) { c.setAttribute("c"); } }

我将分步说明：

声明类型为 Foo的名为 f 的引用并将其分配给类型为 Foo 的新对象，其属性为f。

Declaring a reference named f of type Foo and assign it to a new object of type Foo with an attribute "f". Foo f = new Foo("f");

从方法方面，类型为 Foo 的引用声明名称 a ，并且它最初被分配给 null 。

From the method side, a reference of type Foo with a name a is declared and it's initially assigned to null.

public static void changeReference(Foo a)

当你调用方法 changeReference ，引用 a 将被分配给作为参数传递的对象。

As you call the method changeReference, the reference a will be assigned to the object which is passed as an argument.

changeReference(f);

声明类型为<$ c的名为 b 的引用$ c> Foo 并将其分配给类型为 Foo 的新对象，其属性为b。

Declaring a reference named b of type Foo and assign it to a new object of type Foo with an attribute "b".

Foo b = new Foo("b");