Trouble with creating TreeSet

[MrKP]

To anyone that can point me in the right direction, I'm attempting to create a TreeSet using the Set interface with doesn't allow duplicates. However, it does allow you to just this:

Example: ts.add(John, Doe, ISBN:xxxxxxxxxxx, publisher: ToToo); then possibly retrieve the publishers names alphabetically but I received numerous errors using an iterator. My understanding is that the API list set that interfaces with a TreeSet.

My code is as follows:

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;

public class SetTest {

    private static Object itr;
    private Object aSet;
    private Object bSet;
    private String set;
    private String element;
    private Iterator<String> b_itr;

    public static void main(String args[])
    {
    private Object bSet;
    
       private void Iterator ()
       {
           
        //create TreeSet
        TreeSet< String > aSet = new TreeSet<String> aSet );
        
         //Use iterator to display contents of TreeSet
        System.out.println( "Originals contents of Tree are: " );
        Iterator<String> itr = bSet.iterator();
        while(itr.hasNext()){
            String element = itr.next();
            System.out.println( element + " " );
        
        } //end while
        System.out.println();
       
     } //end private

       //Modify Objects to iterate
       Iterator<String> b_itr = bSet.Iterator();
       while(b_itr.hasNext()){
           String element = b_itr.next();
           b_itr.set(element + "+");
       }

        //Prints the entire list in a sorted order
        System.out.println( "Modified contents of bSet: " );
        itr = bSet.iterator();
        while(itr.hasNext)){
            String str = itr.next();
            System.out.print(str + " ");
        }
        System.out.println();       

	//Objects created Alphabetically in TreeSet listing - can ADD directly
                 TreeSet<Set , String> cSet = new TreeSet<Set , String>();

         //TreeSet ingores duplicates and is added right into the data structure
         cSet.add(  "Johnny", "Smith", "0123456789", "HarperCollins" );
         cSet.add("Freddie", "Jones", "0123456777", "HarperCollins");
         cSet.add("Lilly", "Lane", "0122222234", "Penguin");
         cSet.add("Bobby" , "Crosby" , "0111102345" , "Atlantic" );
         cSet.add("Troy", "James", "0119233334", "Atlantic");

         //Since its sorted we can ask for various subset
         System.out.println( "Lowest(alphabetically) is" + cSet.first());
         
         //Print bSet greater than "k"
         System.out.println(cSet.tailSet("K").toArray[].length + "cSet higher than \"K\"");

         //Prints the entire list alphabetically 
         System.out.println( "Sorted list: " );
         java.util.Iterator - = cSet.iterator();
         while(itr.hasNext())
             System.out.println(itr.next());
    } //end Main

I also tried to create a separate instance variable for doing this process

[Fubarable]

Everything is wrong here, from your trying to have a Set that uses two generic classes (Set and String), to your attempt to use the add method to add multiple Strings to your set object . I suggest you first try a very small program using TreeSet and go from there.

Also, you need to learn to compile often and not add any new code until the code in hand compiles without errors. Otherwise you'll end up with what you have: a rat's nest of errors, and code that can't be fixed and needs to be tossed.