ben niu

Thank you, Paul Clapham. You realy helped me. I remerber I tried several ways to work it out, but what I've tried failed many times. After sevaral days I found myself still cannot figure it out. I'm very frustrated. The problem is really killing me. I have to confess I'm new in data structures and algorithms, although I've been a programer one year, using the J2EE technology to develop websites. Because my major is not Computer Science (SC) when I was in university, so I decided to learn the basic of SC with myself and started from last month. I think learning it well can help me in my futrue career, am I right?

My code goes here:
public class DropOutStack<T> implements StackADT<T> { private final int DEFAULT_CAPACITY = 10; // refers to the item in the array being indexed private int cIndex; // holds the count of the stack private int count; private T[] stack; public DropOutStack() { cIndex = count = 0; stack = (T[]) (new Object[DEFAULT_CAPACITY]); } public DropOutStack(int initialCapacity) { cIndex = count = 0; stack = (T[]) (new Object[initialCapacity]); } public T peek() throws EmptyCollectionException { if (isEmpty()) throw new EmptyCollectionException("Drop-out Stack"); return stack[(cIndex + stack.length - 1)%stack.length]; } public T pop() throws EmptyCollectionException { if (isEmpty()) throw new EmptyCollectionException("Drop-out Stack"); cIndex = (cIndex + stack.length - 1)%stack.length; T result = stack[cIndex]; stack[cIndex] = null; count--; return result; } public void push(T element) { cIndex = cIndex % stack.length; stack[cIndex] = element; cIndex++; if (count != stack.length) count++; } public int size() { return count; } public boolean isEmpty() { return size() == 0; } public String toString() { String str = ""; int temp = cIndex; int length = size(); while(length != 0) { str += stack[(temp + stack.length - 1)%stack.length] + " "; temp--; length--; } return str; } }

Thank you again

I'm using a circular array to implement a drop-out stack, but I've found some problems that made me crazy. Here is my code, and I hope someone could help me out. I wonder how to make the size() and isEmpty() methods. If possible, I also want to know how to make the toString() method. Thanks in advance. BTW, I'm from China and I'm not very good at English. So maybe I used some english words wrongly.
public class DropOutStack<T> implements StackADT<T> { private final int DEFAULT_CAPACITY = 10; private int cIndex; private T[] stack; public DropOutStack() { cIndex = 0; stack = (T[]) (new Object[DEFAULT_CAPACITY]); } public DropOutStack(int initialCapacity) { cIndex = 0; stack = (T[]) (new Object[initialCapacity]); } public T peek() throws EmptyCollectionException { if (isEmpty()) throw new EmptyCollectionException("Drop-out Stack"); return stack[(cIndex + stack.length - 1)%stack.length]; } public T pop() throws EmptyCollectionException { if (isEmpty()) throw new EmptyCollectionException("Drop-out Stack"); cIndex = (cIndex + stack.length - 1)%stack.length; T result = stack[cIndex]; stack[cIndex] = null; return result; } public void push(T element) { cIndex = cIndex % stack.length; stack[cIndex] = element; cIndex++; } public int size() { // I don't know how to make it } public boolean isEmpty() { // I don't know how to make it, either } public String toString() { // Gee, this drop out stack take me several days to implement it }

Hope someone can help me. Thanks a million.