如何在Java中删除子字符串

Question

I am receiving a file path with "xyz" appended to it. name would look like D:/sdcard/filename.docxyz

i am using the below code to remove xyz but it is not working. what is missing here ?

    String fileExtension = path.substring(path.lastIndexOf(".")+1);

    String newExtension= fileExtension;

    newExtension.replace("xyz", "");

    path.replace(fileExtension, newExtension);

    return path;

Answer 1

What is missing is that you need to save the result of your operations. Strings are immutable in Java, and the results of all String manipulations are therefore returned in the form of a new String :

newExtension = newExtension.replace("xyz", "");
path = path.replace(fileExtension, newExtension);

Answer 2

Java中的String是不可变的，对其进行的更改永远不会发生，但是每次返回新的字符串时，

newExtension  = newExtension.replace("xyz", "");

Answer 3

You could also use replaceAll() with a regex.

public static void main(String[] args) {
    String s = "D:/sdcard/filename.docxyz";
    System.out.println(s.replaceAll("xyz$", "")); // $ checks only the end

}

O/P :

 input : s = "D:/sdcard/filename.docxyz";
 D:/sdcard/filename.doc 


 input : String s = "D:/sdcard/filenamexyz.docxyz";
 output : D:/sdcard/filenamexyz.doc

Answer 4

newExtension.replace("xyz", ""); 

Will only return string which has "xyz" removed but newExtension will remain as it is. Simple fix for your problem is use as below

String newExtension= fileExtension.replace("xyz", "");