isEmpty and size methods completed

src/ArrayIntList.java

@@ -0,0 +1,275 @@
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+public class ArrayIntList implements IntList {
+
+    // fields:
+    private int size;
+    private int[] buffer;
+
+    public ArrayIntList() {
+        // initialize my fields
+        size = 0;
+        buffer = new int[10];
+    }
+
+
+    /**
+     * Prepends (inserts) the specified value at the front of the list (at index 0).
+     * Shifts the value currently at the front of the list (if any) and any
+     * subsequent values to the right.
+     *
+     * @param value value to be inserted
+     */
+    @Override
+    public void addFront(int value) {
+        if (size == buffer.length) {
+            resize(size * 2);
+        }
+
+        for (int i = size; i >= 1; i--) {       // count 5, 4, 3, 2, 1
+            buffer[i] = buffer[i - 1];          // copy from 4, 3, 2, 1, 0
+        }
+
+        // put the value at the front of the array at position 0
+        buffer[0] = value;
+        size++;
+    }
+
+    /**
+     * Appends (inserts) the specified value at the back of the list (at index size()-1).
+     *
+     * @param value value to be inserted
+     */
+    @Override
+    public void addBack(int value) {
+        // TODO: check to see if we are full - if so, we need to create a larger buffer
+        if (size == buffer.length) {
+            resize(size * 2);
+        }
+
+        buffer[size] = value;
+        size++;
+    }
+
+    /**
+     * Inserts the specified value at the specified position in this list.
+     * Shifts the value currently at that position (if any) and any subsequent
+     * values to the right.
+     *
+     * @param index index at which the specified value is to be inserted
+     * @param value value to be inserted
+     * @throws IndexOutOfBoundsException if the index is out of range
+     */
+    @Override
+    public void add(int index, int value) {
+        if (size == buffer.length) {
+            resize(size * 2);
+        }
+
+    }
+
+    /**
+     * Removes the value located at the front of the list
+     * (at index 0), if it is present.
+     * Shifts any subsequent values to the left.
+     */
+    @Override
+    public void removeFront() {
+        // call remove(0)
+        if (!isEmpty()) {
+            for (int i = 0; i <= size - 2; i++) {
+                buffer[i] = buffer[i + 1];
+            }
+
+            // optional, but a good idea - since we shifted everything to the left by 1
+            // we want to clear out the right-most value to be zero
+            buffer[size - 1] = 0;
+
+            size--;
+        }
+    }
+
+    /**
+     * Removes the value located at the back of the list
+     * (at index size()-1), if it is present.
+     */
+    @Override
+    public void removeBack() {
+        // call remove(size-1)
+        if (!isEmpty()) {
+            buffer[size - 1] = 0;
+            size--;
+        }
+    }
+
+    /**
+     * Removes the value at the specified position in this list.
+     * Shifts any subsequent values to the left. Returns the value
+     * that was removed from the list.
+     *
+     * @param index the index of the value to be removed
+     * @return the value previously at the specified position
+     * @throws IndexOutOfBoundsException if the index is out of range
+     */
+    @Override
+    public int remove(int index) {
+        // first, check the index to see if it is valid
+        if (index < 0) {
+            throw new IndexOutOfBoundsException("Index cannot be negative");
+        }
+        else if (index >= size) {
+            throw new IndexOutOfBoundsException("Index is higher than size");
+        }
+
+        // save a copy of the value to be removed so we can return it later
+        int copyOfRemovedValue = buffer[index];
+
+        // shift values to the left
+        for (int i = index; i <= size - 1; i++) {
+            buffer[i] = buffer[i+1];
+        }
+
+        buffer[size - 1] = 0;
+
+                // don't forget to decrement size
+        size--;
+
+        return copyOfRemovedValue;
+    }
+
+    /**
+     * Returns the value at the specified position in the list.
+     *
+     * @param index index of the value to return
+     * @return the value at the specified position in this list
+     * @throws IndexOutOfBoundsException if the index is out of range
+     */
+    @Override
+    public int get(int index) {
+        return buffer[index];
+    }
+
+    /**
+     * Returns true if this list contains the specified value.
+     *
+     * @param value value whose presence in this list is to be searched for
+     * @return true if this list contains the specified value
+     */
+    @Override
+    public boolean contains(int value) {
+        return false;
+    }
+
+    /**
+     * Returns the index of the first occurrence of the specified value
+     * in this list, or -1 if this list does not contain the value.
+     *
+     * @param value value to search for
+     * @return the index of the first occurrence of the specified value in this list
+     * or -1 if this list does not contain the value
+     */
+    @Override
+    public int indexOf(int value) {
+        return 0;
+    }
+
+    /**
+     * Returns true if this list contains no values.
+     *
+     * @return true if this list contains no values
+     */
+    @Override
+    public boolean isEmpty() {
+        return false;
+    }
+
+    /**
+     * Returns the number of values in this list.
+     *
+     * @return the number of values in this list
+     */
+    @Override
+    public int size() {
+        return size;
+    }
+
+    /**
+     * Removes all the values from this list.
+     * The list will be empty after this call returns.
+     */
+    @Override
+    public void clear() {
+        buffer = new int[10];
+        size = 0;
+    }
+
+    private void resize(int newSize) {
+        // create new space, separate from the old space (buffer)
+        int[] newBuffer = new int[newSize];
+
+        // copy everything over from buffer into newBuffer
+        for (int i = 0; i < buffer.length; i++) {
+            newBuffer[i] = buffer[i];
+        }
+
+        // set the new space into buffer
+        buffer = newBuffer;
+
+        // the old buffer space is no longer "pointed to" and will eventually
+        // be cleaned up by the garbage collector
+    }
+
+    /**
+     * Returns an iterator over elements of type {@code T}.
+     *
+     * @return an Iterator.
+     */
+    @Override
+    public Iterator<Integer> iterator() {
+        return new IntListIterator();
+    }
+
+    // create a private helper Iterator class
+    private class IntListIterator implements Iterator<Integer> {
+        // private fields:
+        private int i;
+
+        private IntListIterator() {
+            i = 0;
+        }
+
+        /**
+         * Returns {@code true} if the iteration has more elements.
+         * (In other words, returns {@code true} if {@link #next} would
+         * return an element rather than throwing an exception.)
+         *
+         * @return {@code true} if the iteration has more elements
+         */
+        @Override
+        public boolean hasNext() {
+            return i < size;
+        }
+
+        /**
+         * Returns the next element in the iteration.
+         *
+         * @return the next element in the iteration
+         * @throws NoSuchElementException if the iteration has no more elements
+         */
+        @Override
+        public Integer next() {
+            if (i >= size) {
+                throw new NoSuchElementException("i is now out of bounds");
+            }
+            int currentValue = buffer[i];
+            i++;
+            return currentValue;
+        }
+    }
+
+    // iterators are what enables main/client to use a for-each loop
+    // on my IntList
+
+
+}