我可以通过Java的引用传递参数？ [英] Can I pass parameters by reference in Java?

问题描述

我想类似 C＃语义的 REF 关键字。

I'd like semantics similar to C#'s ref keyword.

推荐答案

由于一切都按值传递Java是令人困惑。然而，对于引用类型的参数的 的（即不是原始类型的参数），它的这是按值传递引用本身的，因此它的出现是传递按引用（人们经常声称它是）。不是这种情况下，如由以下

Java is confusing because everything is passed by value. However for a parameter of reference type (i.e. not a parameter of primitive type) it is the reference itself which is passed by value, hence it appears to be pass-by-reference (and people often claim that it is). This is not the case, as shown by the following:

Object o = "Hello";
mutate(o)
System.out.println(o);

private void mutate(Object o) { o = "Goodbye"; } //NOT THE SAME o!

将打印您好到控制台。如果你想上面的code打印再见了的选项是的使用显式引用的如下：

Will print Hello to the console. The options if you wanted the above code to print Goodbye are to use an explicit reference as follows:

AtomicReference<Object> ref = new AtomicReference<Object>("Hello");
mutate(ref);
System.out.println(ref.get()); //Goodbye!

private void mutate(AtomicReference<Object> ref) { ref.set("Goodbye"); }

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