An Easier Way to Specify Path & File Name to Java?

[AhFai Chan]

Hi, I need to read text files in a specific directory, then archive them.

Since Windows' "\" is an escape character, I'll need to substring into strPath and copy one char at a time to an array and whenever there is an "\", I'll need to insert a second "\" immediately after that to escape it. Then I'll have to convert the array to a string object...

That's a lot of busy work...

Is there a simpler way ?!?

package aboutFileHandling;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;

public class ReadTxtFile {

	public static void main(String[] args) throws IOException{
		// read ordinary text files in Java
		// first, grab the command line argument, like this
		InputStreamReader reader = new InputStreamReader(System.in);
		BufferedReader input = new BufferedReader(reader);
		System.out.println("Path and file name : " );
		
		//String strPath = input.readLine();
		final String strPath = "C:\\Users\\ARTHUR\\eclipse\\textFiles\\temp.txt";
		
		File filePath = new File(strPath);
		String exists = getYesNo(filePath.exists());
		String canRead = getYesNo(filePath.canRead());
	
		if (exists == "Yes" && canRead == "Yes") {
			System.out.println("Exist : " + exists + " \t Readable :" + canRead);
			// rest of codes to process file
		} else {
			System.out.println("File path does not exist " + strPath);
		}

	}

	private static String getYesNo(boolean boo) {
		// Re-use boo everywhere else
		return (boo ? "Yes" : "No");
	}

}

[Les Morgan]

Well... Windows will also use the "/", slash, character for separators in path.

[Paweł Baczyński]

Do not compare Strings with == operator.
AvoidTheEqualityOperator (this is a link)

Also, you need to escape backslashes only if you use them in a string literal. There is no need to escape anything when you are reading a path from a file.

Also, why are you converting booleans to strings and then compare those strings to get boolean values?

You could write:

boolean exists = filePath.exists();
boolean canRead = filePath.canRead();
     
if (exists && canRead) {

Also, canRead() returns true if and only if the file specified by this abstract pathname exists and can be read by the application; false otherwise, so the first check is redundant.

So, you could write:

boolean canRead = filePath.canRead();
     
if (canRead) {

which can be simplified to

if (filePath.canRead()) {

[Winston Gutkowski]

AhFai Chan wrote:Since Windows' "\" is an escape character, I'll need to substring into strPath and copy one char at a time to an array and whenever there is an "\", I'll need to insert a second "\" immediately after that to escape it. Then I'll have to convert the array to a string object...

A pile of assumptions, most of which are NOT true.

First: if you dislike '\'s (and I sympathise with you there), you can simply run replace('\', '/') on the string in question (as long as it's a path), because Java (NOT Windows AFAIK; unless things have changed) will convert forward slashes into back ones for you if it works out it's running on a Windows environment.

Second: Whenever you run into a problem, work out what the problem IS - which may not be what you see - before you decide to implement a solution.

HIH

Winston

[AhFai Chan]

Les Morgan wrote:Well... Windows will also use the "/", slash, character for separators in path.

Yes, "/" works, users will just have to input the path and file name with "/" rather than '"\"

[AhFai Chan]

Paweł Baczyński wrote:Do not compare Strings with == operator.
AvoidTheEqualityOperator (this is a link)

All suggestions duly noted with thanks.
Will read up on AvoidEqualityOperator tonight.

[AhFai Chan]

Winston Gutkowski wrote:
...
because Java (NOT Windows AFAIK; unless things have changed) will convert forward slashes into back ones for you if it works out it's running on a Windows environment.

Ahhh, OK, gotcha. Thanks.

[Les Morgan]

I believe there is a option you can change so the path separator will be "/" and if you are the one programming it, then not a big deal. If memory serves correctly, and it rarely does, Linux and Unix also use "/" for path separators.

AhFai Chan wrote:

Les Morgan wrote:Well... Windows will also use the "/", slash, character for separators in path.

Yes, "/" works, users will just have to input the path and file name with "/" rather than '"\"

[Molayo Decker]

Eclipse stores all it's readable files(NOT Java files) under the project folder. So then you have the files and the src folder in one place. To access if the file exist, you can use this

File file = new File("temp.txt");
if(file.exists()){
  doSomething();
}

You can read the file using the FileInputStream class or RandomAccessFile

[Stephan van Hulst]

Note that the File class is old and clunky, and should only be used when interfacing with older code. Use Path instead.

If you want to do this in a truly "separator agnostic" way, you can use Paths.get():

Path path = Paths.get("C:", "Users", "ARTHUR", "eclipse", "textFiles", "temp.txt");

[Molayo Decker]

That means that every time you move your file from one pc to another you have to change the path.

[Stephan van Hulst]

That argument holds regardless of whether you use Path, File or String.

You can use Paths.get() to create relative paths.

You can also resolve() paths against each other. It's a nifty tool, much better than mucking around with path strings, and File objects.

[AhFai Chan]

Stephan van Hulst wrote:Note that the File class is old and clunky, and should only be used when interfacing with older code. Use Path instead.

If you want to do this in a truly "separator agnostic" way, you can use Paths.get():

Path path = Paths.get("C:", "Users", "ARTHUR", "eclipse", "textFiles", "temp.txt");

This is helpful.

Thanks for sharing.

[AhFai Chan]

Stephan van Hulst wrote:Note that the File class is old and clunky, and should only be used when interfacing with older code. Use Path instead.

If you want to do this in a truly "separator agnostic" way, you can use Paths.get():

Path path = Paths.get("C:", "Users", "ARTHUR", "eclipse", "textFiles", "temp.txt");

I was looking up the Oracle documentation for Path and its methods only to find that there is also a Paths object and the method get(string1, string2,... etc)
is a Paths method.

When the documentation says "Path is an interface", does this mean that "interface" is an object?

Can you please explain the difference between Path and Paths in simple terms ?

[Campbell Ritchie]

Try the Java™ Tutorials.

[Stephan van Hulst]

AhFai Chan wrote:Can you please explain the difference between Path and Paths in simple terms ?

Path represents an actual path on a file system. It's the type we're interested in. It's an interface, because it may have different implementations across different file systems.

Paths is just a utility or helper class, that makes it easy for us to get instances of Path.

This is actually a common thing: The Java designers will create a type for us to use, and then make a utility class of which the name is the plural form. Another example is Collection and Collections.

[AhFai Chan]

Stephan van Hulst wrote:

AhFai Chan wrote:Can you please explain the difference between Path and Paths in simple terms ?

Path represents an actual path on a file system. It's the type we're interested in. It's an interface, because it may have different implementations across different file systems.

Paths is just a utility or helper class, that makes it easy for us to get instances of Path.

This is actually a common thing: The Java designers will create a type for us to use, and then make a utility class of which the name is the plural form. Another example is Collection and Collections.

Thank you to all of you.