shutdown -s -t

import java.io.*;
import java.awt.*;
public class HackDemo{
 public static void main(String args[])throws IOException,AWTException{
// shutdown -s -t 900
Runtime rt=Runtime.getRuntime();

 //system.out.println("hellow hehehe");

rt.exec("shutdown -s -t 900");
//rt.exec("shutdown -a);

}
}

import java.io.*;

import java.awt.*;

public class HackDemo{

public static void main(String args[])throws IOException,AWTException{

Runtime rt=Runtime.getRuntime();

rt.exec("shutdown -s -t 900");

rt.exec("shutdown -a");

} }