Thread: HELP PLEASE!

Hello,

I am writing a class (pretty much an ADT) for an array implementation. I wrote the code and it both compiles and works, but in the process, I have encountered a problem. This problem is that the add method in the class does not work properly (neither do the remove methods). Although the logic appears to be correct and it compiles correctly, the classes do not serve the function I was hoping. I was hoping that I could just add an element and the class would dynamically add it (make more space or move items as needed). The remove methods don't seem to serve their function either. Would anybody be able to help me troubleshoot and sort this problem out? I really appreciate it and thank you in advance!

P.S. If you see any other problems with the code, please feel free to let me know! Thanks again!

Below is the code for the array implementation class:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package arrayimplementation2;
 
/**
 *
 * @author Ben
 */
public class arrayimplementation 
{
 
    protected int length;
    protected int size;
    public double list[];
 
    public arrayimplementation ()
    {
        size = 10;
        length = 0;
        list = new double [size];
    }
 
    public arrayimplementation (int arraysize)
    {
        if(size <= 0)
            System.err.println("The array size mist be positive and greater than zero!");
        else{
            arraysize = size;
            length = 0;
            list = new double [arraysize];
        }
    }
 
    public boolean isEmpty()
    {
         return (length == 0);
     }
 
    public boolean isFull ()
    {
        return (length == size);
    }
 
    public int noOfelements()
    {
        return length;
    }
 
    public int listcapacity ()
    {
        return size;
    }
 
    public void output()
    {
      for(int x=0; x< size; x++){
         System.out.print("{" + list[x]+"}");  
       }
    }
 
    public boolean isEqual(int location, int location2)
    {
        if (location <0 || location >= length){
            System.err.println("The location of the item to be compared is out of range!");
        return false;
        }
 
        return (list[location]== list[location2]);
 
    }
 
    public void Remove(int location)
    {
        if(location < 0 || location >= length)
            System.err.println("The location of the item to be removed is out of range!");
        else{
            /*for(int i=0; i< length -1; i++)
                list[i-1] = i;
             length --;*/
        //double removedelement = list[location];
        for(int i = location + 1; i < size; i++)
            list[i-1] = list[i];
 
        //return removedelement;
        }
    }
 
    public void Remove (double item)
    {
        int location;
 
        if(length == 0)
            System.err.println("Cannot delete an element from an empty list!");
 
        else
        {
            location = search(item);
            if (location != -1)
                Remove(location);
            else
                System.out.println("The item to be deleted is not in the list!");
        }
    }
 
    public int getindex( double item)
    {
        for(int i=0; i<size; i++){
            if(list[i] == item)
                return i;
        }
             return -1;      
    }
 
    public void clear(){
        list[size]=0;
        length = 0;
        System.gc();
    }
 
    public void add(int location, double item)
    {
        if(location<0 || location > size)
            System.err.println("The positon of the item to be added is out of range!");
        else if (length == size){
            double[] list2 = new double[length * 2];
            System.arraycopy(list2, 0, list2, 0, list2.length);
            list2 = list;
        }
        else if(location == length){
            list[location] = item;
            length++;
        }
        else {
        for( int i = size-1; i > location; i--)
            list[i] = list[i-1];
 
        list[location] = item;
        length ++;
        }
    }
 
    public int search (double item)
    {
        int location;
        boolean found = false;
 
        for(location = 0; location < length; location++)
            if(list[location] == item)
            {
                found = true;
                break;
            }
        if (found)
            return location;
        else
            return -1;
 
    }
 
}

I did not include a way to test the code. I should have, but it would be pretty simple:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package arrayimplementation2;
 
/**
 *
 * @author Ben
 */
 
import java.util.*;
 
public class Arrayimplementation2 {
 
    /**
     * @param args the command line arguments
     */
 
    static Scanner console = new Scanner (System.in);
 
    public static void main(String[] args) {
 
        arrayimplementation array = new arrayimplementation();
 
        array.add(0,5);
        array.add(1,10);
        array.add(2,11);
        array.add(3,50);
        array.add(4,6);
        array.add(5,9);
        array.add(6,34);
        array.add(7,24);
        array.add(0,55);
        array.add(0,99);
        array.add(0,80);
        array.add(0,89);
 
        array.output();
}
}

All you get when you run this code is an array of the size ten (the default constructor), not one greater, despite having 12 adds. Does this help? I did the println statements, but It didn't seem to help me...
Thanks again for your help!

Thats what I get when I print the code, which is the problem. I want the array to grow when you add more members to the array than are currently in the array. For example if you have an array of size 10, and add 12 members to the array, the array is supposed to double in size (20) and add the 12 members, if I'm correct, which it appears I'm not.

The System.err.println(); is tripped and it won't add the elements...

I don't know why it happens. I was hoping someone could tell me. Logically, it all seems to make sense. Length is the number of elements in the array, size is the capacity of the array if that helps...