get file extension from file path, relative or absolute

package egtry.file;

import java.io.File;

public class FileExtension {

	public static void main(String[] args)  {
		String input="/java/io/InputStream.java";
		System.out.println(input+"=>"+getExtension(input));
		
		input="readme.txt";
		System.out.println(input+"=>"+getExtension(input));
		
		input="/temp/private.dir/simple";
		System.out.println(input+"=>"+getExtension(input));
	}
	
	public static String getExtension(String filepath) {
		File file=new File(filepath);
		String name=file.getName(); 
		int dotPos=name.lastIndexOf('.'); 
		if (dotPos ==-1) {
			return "";
		} else {
			return name.substring(dotPos+1);
		}
	
	}
}

Output

/java/io/InputStream.java=>java
readme.txt=>txt
/temp/private.dir/simple=>