Thread: missing something so simple....help!

i am trying to add nodes to a list (similiar to a linkedlist) but i keep getting errors at my add method and where i call the add method in my main.

public class LLList<T> {
 
 
		private Node firstNode;	// reference to first node
		private int length;		// number of entries in list
 
		public LLList(){
			clear();
		}
 
		public final void clear() {
			firstNode = null;
			length = 0;
		}
 
		public boolean add(T newEntry) {
			Node newNode = new Node(newEntry);//getting the error here
			if (isEmpty()){
				firstNode = newNode;
			}else{
				Node lastNode = getNodeAt(length);
				lastNode.next = newNode;	// make last node reference new node
			}
			length++;
			return true;
		}
 
		public void display() {
			Node currentNode = firstNode;
			while(currentNode != null){
				System.out.println(currentNode.data);
				currentNode = currentNode.next;
			}
		}
 
		public boolean isEmpty() {
			boolean result;
			if (length == 0){
				assert firstNode == null : "length = 0 but firstNode is not null";
				result = true;
			}else{
				assert firstNode != null : "length not 0 but firstNode is null";
				result = false;
			}
			return result;
		}
 
		/**	Task: Returns a reference to the node at a given position.
		 * 	Precondition: List is not empty; 1 <= givenPosition <= length.
		 * @param givenPosition
		 * @return
		 */
		private Node getNodeAt(int givenPosition){
			assert (!isEmpty() && 1 <= givenPosition && givenPosition <= length);
			Node currentNode = firstNode;
			for (int counter = 1; counter < givenPosition; counter++){
				currentNode = currentNode.next;
			}
			assert currentNode != null;
			return currentNode;
		}
 
		private class Node //private inner class
		{	
			private T data;
			private Node next;
 
			private Node(T dataPortion){
				data = dataPortion;
				next = null;
			}
 
			private Node(T dataPortion, Node nextNode){
				data = dataPortion;
				next = nextNode;
			}
		}// end Node
 
 
 
	public static void main(String[] args) {
		LLList<String> list = new LLList<String>();
		list.add("bobby");//getting the error here
		list.add("joey");
		list.display();
	}
 
}

this is the error i see when i try to compile:

Exception in thread "main" java.lang.ClassFormatError: Duplicate method name&signature in class file LLList$Node
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknow n Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at LLList.add(LLList.java:18)
at LLList.main(LLList.java:84)

your help would be appreciated. thank you!

Hi b094mph,

I just tested your code and it compiled and ran with no errors (via command line). Maybe this is an issue with your IDE or JDK version.

how do i find out which version of JDK i am using? i just tried my code in netbeans IDE and it works. so there is something wrong with my version of eclipse or the jdk.

I re installed eclipse and jdk 1.7. it works now! thanks for all your help guys. I appreciated it!