Exception in thread "main" java.lang.NoClassDefFoundError: kolos/Main

[Radek Ischyrion]

Hi there,

I have copied an pasted a code from an online turorial however it is generating errors on my end. The below is the code I copied and pasted from a web tutorial (so assume it's good). The code is however generating an error in my neatbeans. I excpet this to be fairly easy problem but still this is annoying. I would appreciate some info why this is ocurring

package kolos ;
        import java.io.* ;
class Tut1 {
     public static void main(String args[])
     {
               InputStreamReader istream = new InputStreamReader(System.in) ;
               BufferedReader bufRead = new BufferedReader(istream) ;

               System.out.println("Welcome To My First Java Program");
          try {
               System.out.println("Please Enter In Your First Name: ");
               String firstName = bufRead.readLine();
          }
          catch (IOException err) {
               System.out.println("Error reading line");
          }
     }
}

ERROR

run:
Exception in thread "main" java.lang.NoClassDefFoundError: kolos/Main
Caused by: java.lang.ClassNotFoundException: kolos.Main
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: kolos.Main.  Program will exit.
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

thanks and regards, Radek

[Stephan van Hulst]

Your class is named Tut1, and NetBeans is looking for a class named Main. Either rename your class to Main, or go to your project configuration and change the main class to Tut1.

[Radek Ischyrion]

Stephan,
Appreciate your response, however renaming the .java file didn't help. So didn't help renaming the class...

I have created a bit of code in Eclipse (below). The code is in randomArray.java file and compiles fine.

  import java.util.* ;

class randomArray {
	int[] randArray = new int[10] ;
	Random intRandom = new Random() ;

	void fillArray() {
		for(int i = 0 ; i<10 ; i++ ) {
			randArray[i] = intRandom.nextInt(51) ;
		}
	}
	void showArray() {
		for(int i = 0 ; i<10 ; i++ ) {
			System.out.println("randArray["+ i + "] :" + randArray[i]) ;
		}
	}

	int getMax() {
		int maxofArray = randArray[0] ;
		for(int i = 0 ; i <randArray.length ; i++) {
			if(maxofArray<randArray[i]) {
				maxofArray = randArray[i] ;
			}
		}
		return maxofArray ;
	}

	void sortArray() {
		Arrays.sort(randArray) ;
		System.out.println("Minimum = " + randArray[0]) ;
		System.out.println("Maximum = " + randArray[randArray.length-1]) ;
	}
	int sumArray() {
		int sum = 0 ;
		for(int i = 0 ; i <10 ; i++ ) {
			sum = sum + randArray[i] ;
		}
		return sum ;
	}

	public static void main(String[] args) {

		int sum = 0 ;
		int max = 0 ;

		randomArray randArray1 = new randomArray() ;
		randArray1.fillArray() ;
		randArray1.showArray() ;

		max = randArray1.getMax() ;
				//now print the results
		System.out.println("The Maximum of an array is: " + max) ;

		randArray1.sortArray() ;
		sum = randArray1.sumArray() ;

		System.out.println("The sum of the elements in the array is: " + sum);

		System.out.println("The average of all elements in the array is: " + sum/10);
	}
}  

Now when I created the same file in NetBeans named randomArray.java and copied&pasted the code there, it's giving me the same error message.
NetBeans output:

  run:
Exception in thread "main" java.lang.NoClassDefFoundError: kolos/Main
Caused by: java.lang.ClassNotFoundException: kolos.Main
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: kolos.Main.  Program will exit.
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)  

I find this very confusing and would appreciate if you would be able to shed some light on this.

thanks and regards, Radek

[Henry Wong]

Radek Ischyrion wrote:
I find this very confusing and would appreciate if you would be able to shed some light on this.

As already mentioned, NetBeans is looking to run a class named Main -- and not a class named Tut1 or RandomArray. I don't use netbeans so can't tell you where you went wrong.

Regardless, this looks like a NetBeans tools issue -- so moving to a more appropriate forum.

Henry