We Keep Coding

Java: Possible to name a path with exactly 1 unknown directory?

Lets say I have a directory-structure.
/a/b/c/<unknown name>/d/e/f/<files>
for Windows:
C:\a\b\c\<unknown name>\d\e\f<files>
I know a/b/c is always there and also d/e/f/.
I do not know the directory () between them but I know there is only 1.
Is there a way in Java I can name this path without finding out the name of the 1 unknown directory to access ??
Like so?
/a/b/c/*/d/e/f

Yes, it is possible but probably not as straightforward as you think, you'd use the Files.walk method like follows:
Path root = Paths.get("S:\\Coding\\");
String prefix = "A\\AB";
String suffix = "B\\C";
Path searchRoot = root.resolve(prefix);
System.err.println(searchRoot);
List<Path> paths = Files.walk(searchRoot).filter(f -> f.endsWith(suffix)).collect(Collectors.toList());
paths.forEach(System.out::println);
Outputs:
stderr: S:\Coding\A\AB
stdout: S:\Coding\A\AB\ZZZ\B\C

Lets say you have a dockerized app based on a linux distribution.
You can run this unix command: find . -name d/e/f/yourFilename using Process Builder
This will return the complete filepath to your file which will include the unknown portion. And then you can assign it to a String and use in your Java app.

You can hardcode your search method as indicated in other answers. Or, to stay flexible match against patterns. You would need some pattern language to specify your path:
Shells typically use globbing.
Alternatively you could use regexp to distinguish wanted from unwanted files.
Once you have such a pattern matcher, use a tree walking algorithm (traverse the directory structure recursively), match each absolute path name with your pattern. If it matches, perform some action.
Be aware some globbing seems to exist in Java - see Match path string using glob in Java

Java how to handle a \ on input

I am currently trying to split a String folder. I get the value from a file system and it usually looks something like EAM\Testing.
String folder = "EAM\Testing"
String[] parts = folder.split("\\");
I know \ has special rules to it in java.
String folder = "EAM\\Testing"
String[] parts = folder.split("\\\\");
(I know the code above would work if I could control what the input looked like)
My problem is that I can not control what string folder is as input from a location of a file.
Is there a way to get this to work where folder only has one \ in it?
This is for a recycle bin component I am writing for Documentum a enterprise management system. When a document is deleted and the folder doesn't exist anymore I want to recreate it and inorder to recreate it the folder names must be seperate as I have to create them one at a time.
Here is how I get the name of the folder.
File f = new File(relationRecord.getRepeatingString(
"dp_original_folder_paths",
i));
(This gives an input such as \EAM\testing
String folder1 = f.toString();
I then get rid of the first \ by
String folder = folder1.substring(1);
Which gives me EAM\testing

Well if this is literally a file path, you should consider using the Path class, it'll make your life easier.
Path path = Paths.get("C:\\home\\joe\\foo");
System.out.format("toString: %s%n", path.toString());
System.out.format("getFileName: %s%n", path.getFileName());
System.out.format("getName(0): %s%n", path.getName(0));
System.out.format("getNameCount: %d%n", path.getNameCount());
System.out.format("subpath(0,2): %s%n", path.subpath(0,2));
System.out.format("getParent: %s%n", path.getParent());
System.out.format("getRoot: %s%n", path.getRoot());

Your second option
String[] parts = folder.split("\\\\");
Should work fine for your input string. When you write a string literal like "EAM\\Testing", the resulting string has only one slash. You can read some details on escape sequences in Java there.
The reason you need four slashes in split is because \ is an escape character both for string literals and regular expressions (String#split accepts regular expression as its argument)

You should be doing something like this -
String s = "EAM\\testing";
String a[] = s.split("\\\\");
Here you duplicate the backslash once for the String (since \ is an escape character for String) and again for the regex for the same reason.

Your question seems to be "how can I remove a leading \ from a string:
folder = folder.replaceAll("^\\\\", "");
This searches for a back slash at the start if the string, and if found replaces it with nothing (ie deletes it).
Regarding backslash vs forward slash characters in paths, java handles both.

Java regex to replace file path based on OS

I'm not very sure there is any regex to replace thoese things:
This is a string value read from a xml file saved through Linux machine
<pcs:message schema="models/HL7_2.5.model"/>
and this is the one saved in Windows machine
<pcs:message schema="model\HL7_2.5.model"/>
This is why the file getting an error in eclipse while exported in Linux and imported in Windows or vise versa.
Is there any regex to find and replace the value(slash and back slash) within String? (not XML parsing) based on working OS?
Thanks in advance

str = str.replaceAll("\\\\|/", "\\"+System.getProperty("file.separator"))

Use the "file.separator" system property and base your regexp on that.
http://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html
Also see this: File.separator vs FileSystem.getSeparator() vs System.getProperty("file.separator")?

This should take care of fixing slashes:
String str = xml.replaceAll("\\\\|/", System.getProperty("file.separator"));

Java - How to get the name of a file from the absolute path and remove its file extension?

I have a problem here, I have a String that contains a value of C:\Users\Ewen\AppData\Roaming\MyProgram\Test.txt, and I want to remove the C:\Users\Ewen\AppData\Roaming\MyProgram\ so that only Test is left. So the question is, how can i remove any part of the string.
Thanks for your time! :)

If you're working strictly with file paths, try this
String path = "C:\\Users\\Ewen\\AppData\\Roaming\\MyProgram\\Test.txt";
File f = new File(path);
System.out.println(f.getName()); // Prints "Test.txt"
Thanks but I also want to remove the .txt
OK then, try this
String fName = f.getName();
System.out.println(fName.substring(0, fName.lastIndexOf('.')));
Please see this for more information.

The String class has all the necessary power to deal with this. Methods you may be interested in:
String.split(), String.substring(), String.lastIndexOf()
Those 3, and more, are described here: http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/String.html
Give it some thought, and you'll have it working in no time :).

I recommend using FilenameUtils.getBaseName(String filename). The FilenameUtils class is a part of Apache Commons IO.
According to the documentation, the method "will handle a file in either Unix or Windows format". "The text after the last forward or backslash and before the last dot is returned" as a String object.
String filename = "C:\\Users\\Ewen\\AppData\\Roaming\\MyProgram\\Test.txt";
String baseName = FilenameUtils.getBaseName(filename);
System.out.println(baseName);
The above code prints Test.

Java NIO file path issue

I used the following code to get the path
Path errorFilePath = FileSystems.getDefault().getPath(errorFile);
When I try to move a file using the File NIO, I get the error below:
java.nio.file.InvalidPathException: Illegal char <:> at index 2: \C:\Sample\sample.txt
I also tried using URL.encode(errorFile) which results in the same error.

You need to convert the found resource to URI. It works on all platforms and protects you from possible errors with paths. You must not worry about how full path looks like, whether it starts with '\' or other symbols. If you think about such details - you do something wrong.
ClassLoader classloader = Thread.currentThread().getContextClassLoader();
String platformIndependentPath = Paths.get(classloader.getResource(errorFile).toURI()).toString();

The path \C:\Sample\sample.txt must not have a leading \. It should be just C:\Sample\sample.txt

To make it work on both Windows and Linux\OS X consider doing this:
String osAppropriatePath = System.getProperty( "os.name" ).contains( "indow" ) ? filePath.substring(1) : filePath;
If you want to worry about performance I'd store System.getProperty( "os.name" ).contains( "indow" ) as a constant like
private static final boolean IS_WINDOWS = System.getProperty( "os.name" ).contains( "indow" );
and then use:
String osAppropriatePath = IS_WINDOWS ? filePath.substring(1) : filePath;

To be sure to get the right path on Windows or Linux on any drive letter, you could do something like this:
path = path.replaceFirst("^/(.:/)", "$1");
That says: If the beginning of the string is a slash, then a character, then a colon and another slash, replace it with the character, the colon, and the slash (leaving the leading slash off).
If you're on Linux, you shouldn't end up with a colon in your path, and there won't be a match. If you are on Windows, this should work for any drive letter.

Another way to get rid of the leading separator is to create a new file and convert it to a string then:
new File(Platform.getInstallLocation().getURL().getFile()).toString()

try to use like this C:\\Sample\\sample.txt
Note the double backslashes. Because the backslash is a Java String escape character, you must type two of them to represent a single, "real" backslash.
or
Java allows either type of slash to be used on any platform, and translates it appropriately. This means that you could type. C:/Sample/sample.txt
and it will find the same file on Windows. However, we still have the "root" of the path as a problem.
The easiest solution to deal with files on multiple platforms is to always use relative path names. A file name like Sample/sample.txt

Normal Windows Environment
Disclaimer: I haven't tested this on a normal windows environment.
"\\C:\\" needs to be "C:\\"
final Path errorFilePath = Paths.get(FileSystems.getDefault().getPath(errorFile).toString().replace("\\C:\\","C:\\"));
Linux-Like Windows Environment
My Windows box has a Linux-Like environment so I had to change "/C:/" to be "C:\\".
This code was tested to work on a Linux-Like Windows Environment:
final Path errorFilePath = Paths.get(FileSystems.getDefault().getPath(errorFile).toString().replace("/C:/","C:\\"));

Depending on how are you going to use the Path object, you may be able to avoid using Path at all:
// works with normal files but on a deployed JAR gives "java.nio.file.InvalidPathException: Illegal char <:> "
URL urlIcon = MyGui.class.getResource("myIcon.png");
Path pathIcon = new File(urlIcon.getPath()).toPath();
byte bytesIcon[] = Files.readAllBytes(pathIcon);
// works with normal files and with files inside JAR:
InputStream in = MyGui.class.getClassLoader().getResourceAsStream("myIcon.png");
byte bytesIcon[] = new byte[5000];
in.read(bytesIcon);