Writing a baby android app to lock my computer remotely, I'm sure this has its issues, but works on my machine :)

gistfile1.java

package com.zombietank;

import java.io.IOException;

public class SystemControl {
	
	public boolean lockComputer() {
		return executeAndWait("rundll32.exe", "user32.dll,LockWorkStation");
	}
	
	private boolean executeAndWait(String... commands) {
		try {
			Process process = execute(commands);
			process.waitFor();
			return process.exitValue() == 0;
		} catch (IOException | InterruptedException e) {
			return false;
		}
	}
	
	private Process execute(String... commands) throws IOException {
		ProcessBuilder processBuilder = new ProcessBuilder(commands);
		return processBuilder.start();
	}
}