CODEWITHSUNDEEP
javafilefinddirectorynames
James
James

Reputation: 113

Java find start of file name and extension

HI, I have almost solved this but have now got stuck! What I need to do is look in a folder say..

String path = C://;

I then need a loop to see how many files are in that folder say 10. I need to look for files that start like

LAYER.EXE-******.pf

***** can change depending of other things but thats not important what is, is making sure when it finds a file that starts LAYER.EXE- it flags it up. Below is what I have been working on, I would vert much like you're help and thank you in advance! :)

    String path = "C://";
    String files;
    File folder = new File(path);
    File[] listOfFiles = folder.listFiles();

    for (int i = 0; i < listOfFiles.length; i++){
        if (listOfFiles[i].isFile()){
                files = listOfFiles[i].getName();
                System.out.println(files);
                if (files == "LAYER.EXE.pf"){
                    System.out.println("found =================");
            }
        }
    }

Upvotes: 4

Views: 8862

Answers (8)

Andreas Dolk
Andreas Dolk

Reputation: 114817

If you need to filter filenames, then consider using a filename filter:

File[] files = directory.listFiles(new FilenameFilter() {
     public boolean accept(File dir, String fileName) {
       return fileName.startsWith("LAYER.EXE-") && fileName.endsWith(".pf");
     }
   });

This filter is based on your requirements and not on your current implementation.

The files array now only contains File objects whose the filenames are accepted by the filter, in other words, files that match the "pattern" LAYER.EXE-****.pf

Upvotes: 1

Iulius Curt
Iulius Curt

Reputation: 5114

You can use a FileFilter to obtain only the files that fit your name pattern. Like this:

String path = "C://";  
File folder = new File(path);    
File[] listOfFiles = folder.listFiles(new FileFilter(){  
    public boolean  accept(File f){  
        return (f.startsWith("LAYER.EXE"));  
    }  
});

And there you'll have an array with all the files you need, and only them. Next you can test if the array is void and if not handle the files.

Upvotes: 0

Luciano Fiandesio
Luciano Fiandesio

Reputation: 10215

You can use FileNameFilter

public void listFiles() {

        File f = new File("C:/");
        String[] allFiles = f.list(new MyFilter ());
        for (String filez:allFiles ) {
            System.out.println(filez);
        }
    }
    class MyFilter implements FilenameFilter {


        @Override
        public boolean accept(final File dir, final String name) {
            return name.startsWith("LAYER.EXE.pf");
        }
    }

Upvotes: 3

Jakob Nilsson-Ehle
Jakob Nilsson-Ehle

Reputation: 64

First of all, for string comparisons in Java, you need to do .equals() instead of == as == will actually only evaluate to true if the strings are the same object, instead of comparing the values of the strings themselves.

So that would be if(files.equal("LAYER.EXE.pf"))"

Secondly, you should use the .startsWith() function to check if the first characters of a string matches another string

So, just do if(files.startsWith("LAYER.EXE")) and you should be fine

Upvotes: 0

SimonC
SimonC

Reputation: 6718

You want to compare the file names using one of the string comparisons, probably files.startsWith("LAYER.EXE.pf"). equals() (in this case) only returns true if the two objects are the same instance.

Upvotes: 0

Dunaril
Dunaril

Reputation: 2795

To check a String against another you should not use "==", but rather the equals method, or else you will compare the objects' references instead of the expressions. You can also use a better loop by making an iteration over your listOfFiles. Here is the corrected code :

String path = "C://";
    String files;
    File folder = new File(path);
    File[] listOfFiles = folder.listFiles();

    for (File checkedFile : listOfFiles){
        if (checkedFile.isFile()){
                files = checkedFile.getName();
                System.out.println(files);
                if (files.equals("LAYER.EXE.pf")){
                    System.out.println("found =================");
            }
        }
    }

Upvotes: 0

Pablo Santa Cruz
Pablo Santa Cruz

Reputation: 181460

If you need files that start with LAYER.EXE then you better change this:

if (files == "LAYER.EXE.pf")

Into:

if (files.startsWith("LAYER.EXE.pf"))

Please keep in mind that == operator on strings in Java won't behave as you might expect. Use equals or equalsIgnoreCase methods instead!

Upvotes: 0

Vladimir Ivanov
Vladimir Ivanov

Reputation: 43108

files == "LAYER.EXE.pf"

change to 

"LAYER.EXE.pf".equals(files)

What you do is a reference comparison, and you need the equality. Read more here.

Telling more, this will give you only the files which name is equal to "LAYER.EXE.pf".

Try files.startsWith("LAYER.");

Upvotes: 6

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