public void compile ()
{
     byte[] buffer1 = new byte[2048];
     int len = 0;
    String str9 = "C:ddk1.4/bin/javac";
     String str10 = "D:gui.java";
     String[] str11 = {str9, str10};
  File File11 = new File("C://JIDE_Errors.TXT");
 
try
{
       Runtime1 = Runtime.getRuntime();
//The below command command line is where the exception 
//occurs saying it is a null pointer exception
 
        Process1 = Runtime1.exec(str11);
          InputStream in = new BufferedInputStream(Process1.getErrorStream());
        FileOutputStream out = new FileOutputStream(File11);
 
while((len = in.read(buffer1)) != -1)
{
          out.write(buffer1, 0, len);
}
 
         Process1.waitFor();
 
if(Process1.exitValue() == 0)
{
              System.out.println("Compilation Successful");
}
 
else
{
 
}
 
}

 
    String[] str12 ={"C:/j2sdk1.4.2_04/bin/java", "C:/JButtons"}; 
 
      Runtime Runtime1;
      Process Process1;
 
try
{
       Runtime1 = Runtime.getRuntime();
       Process1 = Runtime2.exec(str12);
 
       Process1.waitFor();
}
 
catch(Exception e)
{
       e.printStackTrace();
}