字符串修剪功能不起作用 [英] string trim function is not working

问题描述

我了解到 string.trim()删除了前导和尾随空格.但是在我的情况下，它无法正常工作，我正在尝试使用以下代码，但输出具有前导和尾随空格.但是我的期望是文本没有开头和结尾的空格.这是我的代码.

I learned string.trim() removes leading and trailing spaces. But in my case its not working i am trying below code but output is with leading and trailing space. But my expectation is text without leading and trailing space. Here is my code.

String s = " Hello Rais ";
s += " Welcome to my World ";
s.trim( );
System.out.println(s);

请帮助我

推荐答案

您需要将 trim 的结果重新分配回 s :

You need to re-assign the result of trim back to s:

s = s.trim();

请记住， Java中的字符串是不可变的 ，因此几乎所有String类方法将创建并返回新的字符串，而不是修改字符串就位.

Remember, Strings in Java are immutable, so almost all the String class methods will create and return a new string, rather than modifying the string in place.

尽管这是题外话，但是(正如我在几乎那里所说的)，值得知道的是，此规则的例外是在创建相同长度的 substring 时，或者方法在任何时候返回具有相同值的字符串，这将被优化并且不会创建新字符串，而只需返回 this .

Although this is off-topic, but (as I said there almost), it's worth knowing that, exception to this rule is when creating a substring of same length, or any time a method returns the string with the same value, which will be optimized and will not create a new string, but simply return this.

String s = "Rohit";
String s2 = s.substring(0, s.length());

System.out.println(s == s2); // will print true

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