Java：切断字符串末尾的更简单方法
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Java: simpler way of cutting off end of string
提问by BAERUS
Everytime I encounter this I ask myself the same question: Isn't there a simpler and less annoying way of cutting a string from the end by X characters.
每次我遇到这个问题时，我都会问自己同样的问题：是否有一种更简单且不那么烦人的方法可以将字符串从末尾剪下 X 个字符。
Let's say I got "Helly there bla bla"and - why ever - I need to cut off the last 2 characters, resulting in "Helly there bla b".
I now would do the following:
假设我得到了"Helly there bla bla"- 为什么 - 我需要切断最后 2 个字符，导致"Helly there bla b". 我现在会做以下事情：
String result = text.substring(0, text.length() - 2);
I rather want to do something like:
我宁愿做这样的事情：
String result = text.cutOffEnd(2);
I know there are many String libraries out there, but don't know many of them and I never saw something like that so I hoped someone of you might know better :)
我知道那里有很多 String 库，但不知道其中很多，而且我从未见过类似的东西，所以我希望你们中的某个人可能更了解 :)
EDIT:
编辑：
Q:Why don't you just build your own util method / class?
问：为什么不构建自己的 util 方法/类？
A:I don't want to use an own util method. I don't write a util method for "null or empty" or other trivial things. I go with the opinion that there MUST BE something available already as I would say that tons of people need this kind of function pretty often in their lifetime. Plus: I work in many different projects and just want to rely on a simple library call like "Strings.nullToEmpty(str)" etc. I just don't build something like that on my own, although it's trivial.
A：我不想使用自己的 util 方法。我不会为“空或空”或其他琐碎的事情编写 util 方法。我认为必须已经有一些可用的东西，因为我会说很多人在他们的一生中经常需要这种功能。另外：我在许多不同的项目中工作，只是想依赖一个简单的库调用，比如“Strings.nullToEmpty(str)”等。我只是不会自己构建类似的东西，尽管它很简单。
Q:why is text.substring(0, text.length() - 2);not good enough?
问：为什么text.substring(0, text.length() - 2);不够好？
A:It's very bulky if you compare it with my desired function. Also, think of that: If you determine the string, it becomes even unhandier:
A：和我想要的功能比起来就很笨重了。另外，请想一想：如果您确定字符串，它会变得更加不方便：
String result = otherClass.getComplicatedCalculatedText(par1, par2).substring(0,
otherClass.getComplicatedCalculatedText(par1, par2).length() - 2);
Obviously I'd need to use a local variable, which is so unnecessary at this point... As it could simply be:
显然我需要使用一个局部变量，这在这一点上是不必要的......因为它可能只是：
String result = otherClass.getComplicatedCalculatedText(par1, par2).cutOffEnd(2);
回答by Rustam
By using some string library. I suggest Apache's commons lang.
通过使用一些字符串库。我建议使用 Apache 的公共语言。
For your case this is enough.
对于你的情况，这就足够了。
import org.apache.commons.lang.StringUtils;
String result = StringUtils.removeEnd( "Helly there bla bla", "la");
回答by Dhanushka Gayashan
Go through the following code
通过以下代码
public class OddNumberLoop {
public static void main(String[] args) {
String st1 = "Helly there bla bla";
String st2 = st1.substring(0, st1.length() - 2);
System.out.println(st2);
}
}
}
Good Luck !!!
祝你好运 ！！！
回答by icza
There is no built-in utility for this in the starnard library, but how hard is it to write a util method for this yourself?
starnard 库中没有为此提供内置实用程序，但是自己为此编写一个 util 方法有多难？
public static String cutOffEnd(String s, int n) {
return s == null || s.length() <= n ? "" : s.substring(0, s.length() - n);
}
A complete solution with checks included:
包含检查的完整解决方案包括：
public static String cutOffEnd(String s, int n) {
if (s == null)
throw new NullPointerException("s cannot be null!");
if (n > s.length())
throw new IllegalArgumentException("n cannot be greater"
+ " than the length of string!");
return s.substring(0, s.length() - n);
}
回答by Grim
- By the way: Often such feature-requests are made to the java-compiler. Usually these features are not Compelling for the Language and won't be fixed.
- Why do you like to cut it off? If its for a higher-level-solution then you like to match a pattern or structure. In this case you anyway shall use a own Util-Methodfor parsing.
- 顺便说一句：通常此类功能请求是向 java 编译器发出的。通常这些功能对于语言来说并不引人注目，也不会被修复。
- 你为什么喜欢剪掉它？如果它用于更高级别的解决方案，那么您喜欢匹配模式或结构。在这种情况下，您无论如何都应使用自己的 Util-Method进行解析。
A realistic Example:
一个现实的例子：
String url = "http://www.foo.bar/#abc";
String site = url.substring(0, url.indexOf("#"));
// this shall be extracted into a utils-method
// anyway like `MyURLParser.cutOfAnchor()`.
Its forbidden to ask for a concrete Library here.
禁止在这里索取具体的图书馆。
