How to invoke substring(int, int) on the array type String[] in Java

Question

I have a file name reader from a folder.file`s names taken into a string array.what i want is when i executed this code segment i want the file name without its extension. But still extensions get printed out.

import java.io.File;
public class Main {

    public static void main(String[] args) {
        File file=new File("D:\\C_App\\PDF");
        String[] files = file.list();
        for(String string : files) {
            string.substring(0, string.length());
            System.out.println(string);
        }
    }
}

Can anyone help me to solve this? Thanks.

Just so you ALL know...A file name doesn't necessarily need to contain a file name extension. NONE of your answers takes this into account. @D.Anush - Check out the thread in [this SO Post](https://stackoverflow.com/questions/924394/how-to-get-the-filename-without-the-extension-in-java). — DevilsHnd - 退職した, Aug 22 '18 at 05:23
Strings are immutable in java. The `substring` method returns a **new** string that you need to assign to a variable. — Mark Rotteveel, Aug 22 '18 at 08:45

Kaustubh Khare · Answer 1 · 2018-08-23T05:11:17.063

1

Take substring of string from the last index of .

import java.io.File;
public class Main {

    public static void main(String[] args) {
        File file=new File("D:\\C_App\\PDF");
        String[] files = file.list();
        for(String string : files) {
             if(new File(string).isFile){ 
               if (string.lastIndexOf(".") > 0) {
                  System.out.println(string.substring(0, a.lastIndexOf('.'));
               }
            else {
               System.out.println(string);
            }
           }
        }
    }
}

edited Aug 23 '18 at 05:11

answered Aug 22 '18 at 04:47

Kaustubh Khare

3,280
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it gives Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at Main.main(Main.java:9). im very new to programming pls help – D.Anush Aug 22 '18 at 04:53
Can you print file name? – Kaustubh Khare Aug 22 '18 at 04:54
No nothing prints out except that exception. – D.Anush Aug 22 '18 at 04:55
Do `System.out.println(string);` and tell me the output. – Kaustubh Khare Aug 22 '18 at 04:56
File name get printed out with the extension. – D.Anush Aug 22 '18 at 04:57
Yes. show me that output. Can you add that into your question? – Kaustubh Khare Aug 22 '18 at 04:58
@D.Anush I have updated my answer. Which will now check for the string is file or folder. – Kaustubh Khare Aug 22 '18 at 05:06
This is a valid file name in the Windows OS: `te..........st.txt`. – DevilsHnd - 退職した Aug 22 '18 at 05:08
@Kaustubh I build my answer with the help you provided. thanks – D.Anush Aug 22 '18 at 05:09
@DevilsHnd updated answer. thanks – Kaustubh Khare Aug 22 '18 at 05:12
@D.Anush i have updated answer to support DevilsHnd's point. – Kaustubh Khare Aug 22 '18 at 05:13
@Kaustubh - Now work on the fact that a file name doesn't necessarily need to contain a file name extension. – DevilsHnd - 退職した Aug 22 '18 at 05:26

The Scientific Method · Answer 2 · 2018-08-22T05:51:38.577

0

using regex by matching the last dot ( . ) and split,

the regex (\\.)(?!.*\\.) matches the last dot.

import java.io.File;
public class Main {
public static void main(String[] args) {
    File file=new File("D:\\C_App\\PDF");
    String[] files = file.list();
    for(String string : files) {
      if (!string.isEmpty()) {
        System.out.println(string.split("(\\.)(?!.*\\.)")[0]);
      }
    }
}

edited Aug 22 '18 at 05:51

answered Aug 22 '18 at 05:00

The Scientific Method

2,374
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This would be the route I would of taken however I would of also added: `if (new File(string).isDirectory()) { continue; }` to ignore directories names within the list. – DevilsHnd - 退職した Aug 22 '18 at 05:07
@D.Anush can you mark it an answer if it answers your question? – The Scientific Method Aug 22 '18 at 06:39

score 0 · Accepted Answer · answered Aug 22 '18 at 05:03

Here is the Solution:

public static void main(String[] args) {
    File file = new File("D:\\SunilKanjar");
    String[] files = file.list();
    for (String string : files) {
        if (string.lastIndexOf(".") > 0) {
            System.out.println(string.substring(0, string.lastIndexOf(".")));
        }
    }
}

To get file name without extension first of all we need to find is there any extension or not and then need to remove extension only and for that find . at from the last.

It is not accurate to assume that file name not contain more then one . sign.

How to invoke substring(int, int) on the array type String[] in Java

3 Answers3