How to construct a file path in Java

In this tutorial, we will show you three Java examples to construct a file path :

1. File.separator or System.getProperty(“file.separator”) (Recommended)
2. File file = new File(workingDir, filename); (Recommended)
3. Create the file separator manually. (Not recommend, just for fun)

1. File.separator

Classic Java example to construct a file path, using File.separator or System.getProperty("file.separator"). Both will check the OS and returns the file separator correctly, for example,

1. Windows = \
2. *nix or Mac = /

 Example:

package com.example.file;

import java.io.File;

import java.io.IOException;

public class FilePathExample1 {

public static void main(String[] args) {

 try {

String filename = "newFile.txt";

String workingDirectory = System.getProperty("user.dir");

//****************//

String absoluteFilePath = "";

//absoluteFilePath = workingDirectory + System.getProperty("file.separator") + filename;

absoluteFilePath = workingDirectory + File.separator + filename;

System.out.println("Final filepath : " + absoluteFilePath);

//****************//

File file = new File(absoluteFilePath);

if (file.createNewFile()) {

System.out.println("File is created!");

} else {

System.out.println("File is already existed!");

}

 } catch (IOException e) {

e.printStackTrace();

 }

}

}

Output

Final filepath : /Users/mkyong/Documents/workspace/maven/fileUtils/newFile.txt

File is created!

2. new File()

Some developers are using new File() API to construct the file path.

package com.example.file;

import java.io.File;

import java.io.IOException;

public class FilePathExample2 {

public static void main(String[] args) {

 try {

String filename = "newFile.txt";

String workingDirectory = System.getProperty("user.dir");

//****************//

File file = new File(workingDirectory, filename);

//****************//

System.out.println("Final filepath : " + file.getAbsolutePath());

if (file.createNewFile()) {

System.out.println("File is created!");

} else {

System.out.println("File is already existed!");

}

 } catch (IOException e) {

e.printStackTrace();

 }

}

}

Output:

Final filepath : /Users/mkyong/Documents/workspace/maven/fileUtils/newFile.txt

File is created!

3. Manual file separator

Check the system OS and create file path manually, just for fun, not recommend.

Example:

package com.test.file;

import java.io.File;

import java.io.IOException;

public class FilePathExample3 {

public static void main(String[] args) {

 try {

String filename = "testing.txt";

String workingDir = System.getProperty("user.dir");

String absoluteFilePath = "";

//****************//

String your_os = System.getProperty("os.name").toLowerCase();

if (your_os.indexOf("win") >= 0) {

//if windows

absoluteFilePath = workingDir + "\\" + filename;

} else if (your_os.indexOf("nix") >= 0 || 

                           your_os.indexOf("nux") >= 0 || 

                           your_os.indexOf("mac") >= 0) {

//if unix or mac 

absoluteFilePath = workingDir + "/" + filename;

}else{

//unknow os?

absoluteFilePath = workingDir + "/" + filename;

}

System.out.println("Final filepath : " + absoluteFilePath);

//****************//

File file = new File(absoluteFilePath);

if (file.createNewFile()) {

System.out.println("Done");

} else {

System.out.println("File already exists!");

}

 } catch (IOException e) {

e.printStackTrace();

 }

}

}

Output

Final filepath : /Users/mkyong/Documents/workspace/maven/fileUtils/newFile.txt

File is created!