在 Java 中通过引用传递字符串? [英] Passing a String by Reference in Java?

问题描述

我习惯于在 C 中执行以下操作:

I am used to doing the following in C:

void main() {
    String zText = "";
    fillString(zText);
    printf(zText);
}

void fillString(String zText) {
    zText += "foo";
}

输出是:

foo

但是，在 Java 中，这似乎不起作用.我假设是因为 String 对象是 copyed 而不是 通过引用传递.我认为字符串是对象，它们总是通过引用传递.

However, in Java, this does not seem to work. I assume because the String object is copied instead of passed by referenced. I thought Strings were objects, which are always passed by reference.

这里发生了什么?

推荐答案

您有三个选择:

1. 使用 StringBuilder:

1. Use a StringBuilder:

StringBuilder zText = new StringBuilder ();
void fillString(StringBuilder zText) { zText.append ("foo"); }

创建一个容器类并将容器的一个实例传递给您的方法:

Create a container class and pass an instance of the container to your method:

public class Container { public String data; }
void fillString(Container c) { c.data += "foo"; }

创建一个数组:

Create an array:

new String[] zText = new String[1];
zText[0] = "";

void fillString(String[] zText) { zText[0] += "foo"; }

从性能的角度来看，StringBuilder 通常是最好的选择.

From a performance point of view, the StringBuilder is usually the best option.

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