$@|sh – Or: Getting a shell environment from Runtime.exec (http://codewhitesec.blogspot.com/2015/03/sh-or-getting-shell-environment-from.html)

Exec.java

import java.io.*;

public class Exec {

	public static void main(String[] args) throws IOException {
		Process p = Runtime.getRuntime().exec(args[0]);
		byte[] b = new byte[1];
		
		while (p.getErrorStream().read(b) > 0)
			System.out.write(b);
		while (p.getInputStream().read(b) > 0)
			System.out.write(b);
	}

}