So you want to get the real case sensitive names of files stored in your filesystem. Lets imaging we have the following paths:
- on Linux: using ext4 (which is case sensitive)
/testFolder/test.PnG
- on Windows using NTFS (which is not case sensitive)
c:\testFolder\test.PnG
Now lets create some Java File Objects to each Image File.
// on Linux
File f1 = new File("/testFolder/test.png");
File f2 = new File("/testFolder/test.PNG");
File f3 = new File("/testFolder/test.PnG");
f1.exists(); // false
f2.exists(); // false
f3.exists(); // true
// on Windows
File f1 = new File("c:\\testFolder\\test.png");
File f2 = new File("c:\\testFolder\\test.PNG");
File f3 = new File("c:\\testFolder\\test.PnG");
f1.exists(); // true
f2.exists(); // true
f3.exists(); // true
Your problem is that all calls of File like File.exists are redirected to the java.io.FileSystem class that represents real Operating System calls of your File System by the JVM. So you cannot distinguish on Windows Machines between test.PNG and test.png. Neither do Windows itself.
But even on Windows each File has a defined name in the File System that could be for example: test.PnG. You will see this in your Windows Explorer or in Command Line if you type dir c:\testFolder.
So what you can do in Java is use the File.list method on the parent directory that results in the Operating System list call for all files in this directory with their real names.
File dir = new File("c://testFolder//");
for(String fileName : dir.list())
System.out.println(fileName);
// OUTPUT: test.PnG
or if you prefer File Objects
File dir = new File("c://testFolder//");
for(File file : dir.listFiles())
System.out.println(file.getName());
// OUTPUT: test.PnG
You can use this to write your own exists Method that is case sensitive on all operating systems
public boolean exists(File dir, String filename){
String[] files = dir.list();
for(String file : files)
if(file.equals(filename))
return true;
return false;
}
Use it like this:
File dir = new File("c:\\testFolder\\");
exists(dir, "test.png"); // false
exists(dir, "test.PNG"); // false
exists(dir, "test.PnG"); // true
EDIT: I have to admit that I was wrong. There is a way to get the real name of a File. I always overlooked the method File.getCanonicalPath.
Again our example: We have that File c:\testFolder\test.PnG.
File f = new File("c://testFolder//test.png");
System.out.println(f.getCanonicalPath());
// OUTPUT: C:\testFolder\test.PnG
With that knowledge you can write a simple test method for the case sensitive extension without iterating all files.
public boolean checkExtensionCaseSensitive(File _file, String _extension) throws IOException{
String canonicalPath = _file.getCanonicalPath();
String extension = "";
int i = canonicalPath.lastIndexOf('.');
if (i > 0) {
extension = canonicalPath.substring(i+1);
if(extension.equals(_extension))
return true;
}
return false;
}
Use it like this:
File f = new File("c://testFolder//test.png");
checkExtensionCaseSensitive(f, "png"); // false
checkExtensionCaseSensitive(f, "PNG"); // false
checkExtensionCaseSensitive(f, "PnG"); // true
