Java - get file absolute path according to indicated class

In this short article, we would like to show how to find file absolute path according to indicated class in Java.

Usage example:

String path = PathUtils.getAbsolutePath(MyClass.class, "file.txt");  // check the below source code

System.out.println(path);  // C:/projects/test/target/classes/com/example/file.txt

Assumptions

Java project was located in C:/projects/test directory. Java files were located in src/com/example directory according to used com.example package.

Solution

Program.java file:

package com.example;

public class Program {
    
    public static void main(String[] args) {

        String path = PathUtils.getAbsolutePath(Program.class, "file.txt");
        System.out.println(path);  // C:/projects/test/target/classes/com/example/file.txt
    }
}

Notes:

• by default, each class file after compilation is placed in out/ or output/ directory (target/ for maven project),
• to know how to configure *.txt files coppying go to this article.

Example output:

C:/projects/test/target/classes/com/example/file.txt

PathUtils.java file:

package com.example;

import java.net.URL;

public class PathUtils {
    
    private static final boolean IS_WINDOWS;

    static {
        String OS_NAME = System.getProperty("os.name");
        String OS_CODE = OS_NAME.toLowerCase();
        IS_WINDOWS = OS_CODE.contains("win");
    }

    private PathUtils() {
        // Nothing here ...
    }

    public static String getAbsolutePath(Class<?> clazz, String relativePath) {
        URL url = clazz.getResource(relativePath);
        if (url == null) {
            return null;
        }
        String path = url.getPath();
        if (IS_WINDOWS) {
            return path.substring(1);
        }
        return path;
    }
}