将在内存中创建多少个字符串对象?

问题描述

以下代码会创建多少个字符串对象?

How many string objects will be created by the following code?

String s="";
s+=new String("a");
s+="b";

我在考试时遇到了这个问题.我想知道正确答案.我说的是 2 个对象.
池中包含 "" 、 "b" 的对象和 new String("a") 创建的对象；

I had this question at exam. I want to know the right answer . I said 2 objects.
The object from pool that contains "" , "b" and the object created by new String("a");

推荐答案

我将回答另一个更清晰的问题:以下代码片段中涉及多少 String 实例:

I'll anwser to another, clearer question: how many String instances are involved in the following code snippet:

String s="";
s+=new String("a");
s+="b";

答案是 6:

• 空字符串字面量:"";
• 字符串文字 "a";
• 字符串文字a"的副本:new String("a");
• 通过连接s 和"a" 的副本创建的字符串；
• 字符串文字 "b"
• 通过连接 s 和 "b" 创建的字符串.

• the empty String literal: "";
• the String literal "a";
• the copy of the String literal "a": new String("a");
• the String created by concatenating s and the copy of "a";
• the String literal "b"
• the String created by concatenating s and "b".

如果您假设之前加载的代码已经创建了三个 String 字面量，则代码片段因此创建了 3 个新的 String 实例.

If you assume that the three String literals have already been created by previously-loaded code, the code snippet thus creates 3 new String instances.

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