Please help me. I am getting a runtime error.

Question

Package problem in java?
Please help me. I have two packages named app and Util. Util is inside app. In Util i have the file BitUtils.java and in app i have CertkillerApp.java which is the driver file. I am getting error. Please help me.
BitUtils.java :
package Util;
public class BitUtils {
public static void process(new byte[]) {
System.out.println("Inside method byte");
CertkillerApp.java
package app;
public class CertkillerApp {
public static void main(String[] args) {
byte[] bytes = new byte[256];
Util.BitUtils.process(bytes);
Now when i am entering app directory inside D: by cd app and compling by javac CertkillerApp.java. It is compiling but when i am executing from the same directory it is
giving runtime errror.
Output :
D:\APP>java app.CertkillerApp
Exception in thread "main" java.lang.NoClassDefFoundError... app/CertkillerApp

Answer 1

I think I got it.
You said: "Util is inside app", right?
First: package names should allways be with lowercases.
So I would change it for: util.
Second: since the package util is "inside" the package app, then the real name of the package util is: app.util.
It is NOT just util (there is no such thing in Java as partial package names).
So you should have the following folders/files:
D:\
D:\app
D:\app\CertkillerApp.java
D:\app\util
D:\app\util\BitUtils.java
Where BitUtils.java file should start with:package app.util;And CertkillerApp.java should look like:package app;
public class CertkillerApp {
    public static void main(String[] args) {
        byte[] bytes = new byte[256];
        app.util.BitUtils.process(bytes);
}Then you should compile them:cd  D:\
javac  -classpath  .  app\*.java  app\util\*.javaThen run it:cd  D:\
java  -classpath  .  app.CertkillerAppRegards