Stringbuilder在java中进行字符串转换 [英] Stringbuilder to string conversion in java

问题描述

我知道我们可以使用toString（）和new String（stringbuilder）函数和构造函数将字符串构建器转换为字符串。但是我想知道为什么这个语句引发错误的原因是StringBuilder无法转换为String

I know we can convert a string builder to string using toString() and new String(stringbuilder) functions and constructor.. But I want to know the reason why this statement raises an error as "StringBuilder cannot be converted to String"

String s = (String) StringBuilder;

我尝试过：



将stringbuilder转换为字符串使用string literal

What I have tried:

Convert stringbuilder to string using string literal

推荐答案

因为 StringBuilder 是一个不同的类，不能直接用作字符串。您必须使用 toString（）方法，如文档中所述。

Because a StringBuilder is a different class, and cannot be directly used as a String. You must use the toString() method, as described in the documentation.

没有<$ c $之类的东西c> StringBuilder 到字符串转换。

StringBuilder class为您提供 toString 方法，该方法允许您获取实际存储在 StringBuilder 的内部缓冲区中的字符串对象。

你必须使用

There is no such thing as a StringBuilder to String conversion.
StringBuilder class provides you with a toString method which allows you to get the string which is actually stored in the internal buffer of the StringBuilder object.
You have to use

String s = sb.ToString();

， sb 是 StringBuilder 类的变量。

, sb being a variable of the StringBuilder class.

// Bad code!
String s = (String)StringBuilder;

是至少在两个级别上不正确：

• 你不能施放 StringBuilder 变量到stri直接。
  
  
• StringBuilder 是一个类，而不是一个变量。你不能把类投射到任何东西上，你只能投射变量。
  
  


is not correct on at least two levels:




• You cannot cast a StringBuilder variable to a string directly.
  
• StringBuilder is a class, not a variable. You cannot cast a class to anything, you only cast variables.
  




嗯，我想在类型转换你的情况下我必须检查IS-A测试，在这种情况下会失败，因为StringBuilder不是String。在转换的情况下，你明确地必须使用toString（）（注意't'不是大写）。

Well, I guess in case of type casting you'll have to take check for the "IS-A" test which would fail in this case as StringBuilder is NOT a String. In case of conversion you explicitly have to use the "toString()"(note that 't' isn't capital).




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