Custom Vector Implementation

Author: deepak-malik

src/com/deepak/data/structures/Vector/CustomVector.java

@@ -4,11 +4,288 @@
  */
 package com.deepak.data.structures.Vector;
 
+import java.util.Enumeration;
+import java.util.NoSuchElementException;
+
 /**
  * Implementation of Vector
  * 
  * @author Deepak
  */
-public class CustomVector {
+public class CustomVector<T> {
+
+	/* Array to hold elements */
+	private Object[] elements;
+
+	/* Size of vector */
+	private int size;
+
+	/* Variable for capacity increment when array gets full */
+	private int capacityIncrement;
+
+	/* Default capacity */
+	private final static int DEFAULT_CAPACITY = 10;
+
+	/**
+	 * Constructor
+	 */
+	public CustomVector() {
+		this(DEFAULT_CAPACITY);
+	}
+
+	/**
+	 * Constructor
+	 * 
+	 * @param capacity
+	 */
+	public CustomVector(int capacity) {
+		this(capacity, 0);
+	}
+
+	/**
+	 * Constructor
+	 * 
+	 * @param capacity
+	 * @param capacityIncrement
+	 */
+	public CustomVector(int capacity, int capacityIncrement) {
+		if (capacity < 0) {
+			throw new IllegalArgumentException("Illegal Capacity: " + capacity);
+		} 
+		this.elements = new Object[capacity];
+		this.capacityIncrement = capacityIncrement;
+	}
+
+	/**
+	 * Method to return current capacity of vector
+	 * 
+	 * @return {@link int}
+	 */
+	public synchronized int capacity() {
+		return elements.length;
+	}
+
+	/**
+	 * Method to return current size of vector
+	 * 
+	 * @return {@link int}
+	 */
+	public synchronized int size() {
+		return size;
+	}
+
+	/**
+	 * Method to check if vector is empty
+	 * 
+	 * @return {@link int}
+	 */
+	public synchronized boolean isEmpty() {
+		return size() == 0;
+	}
+
+	/**
+	 * Method to return enumeration of elements
+	 * 
+	 * @return {@link Enumeration}
+	 */
+	public Enumeration<T> elements() {
+		return new Enumeration<T>() {
+			int count = 0;
+
+			public boolean hasMoreElements() {
+				return count < size;
+			}
+
+			public T nextElement() {
+				synchronized (CustomVector.this) {
+					if (count < size) {
+						return elementData(count++);
+					}
+				}
+				throw new NoSuchElementException("Vector Enumeration");
+			}
+		};
+	}
+
+	/**
+	 * Method to check if vector contains the object
+	 * 
+	 * @param o
+	 * @return {@link boolean}
+	 */
+	public synchronized boolean contains(Object o) {
+		return indexOf(o) >= 0;
+	}
+
+	/**
+	 * Method to check the index of a given object
+	 * 
+	 * @param o
+	 * @return {@link int}
+	 */
+	public synchronized int indexOf(Object o) {
+		return indexOf(o, 0);
+	}
+
+	/**
+	 * Method to find the index of a given object
+	 * 
+	 * @param o
+	 * @param index
+	 * @return {@link int}
+	 */
+	private synchronized int indexOf(Object o, int index) {
+		/* If object is null, return the first index of null value */
+		if (o == null) {
+			for (int i = 0; i < size; i++) {
+				if (elements[i] == null) {
+					return i;
+				}
+			}
+		} else {
+			for (int i = 0; i < size; i++) {
+				if (o.equals(elements[i])) {
+					return i;
+				}
+			}
+		}
+		return -1;
+	}
+
+	/**
+	 * Method to find element at given index
+	 * 
+	 * @param index
+	 * @return {@link T}
+	 */
+	public synchronized T elementAt(int index) {
+		if (index >= size) {
+			throw new ArrayIndexOutOfBoundsException(index + " >= " + size);
+		}
+		return elementData(index);
+	}
+
+	/**
+	 * Method to find the first element
+	 * 
+	 * @return {@link T} 
+	 */
+	public synchronized T firstElement() {
+		if (size == 0) {
+			throw new NoSuchElementException();
+		}
+		return elementData(0);
+	}
+
+	/**
+	 * Method to find the last element
+	 * 
+	 * @return {@link T}
+	 */
+	public synchronized T lastElement() {
+		if (size == 0) {
+			throw new NoSuchElementException();
+		}
+		return elementData(size - 1);
+	}
+
+	/**
+	 * Method to set the element at a given index
+	 * 
+	 * @param object
+	 * @param index
+	 */
+	public synchronized void setElementAt(T object, int index) {
+		if (index >= size) {
+			throw new ArrayIndexOutOfBoundsException(index + " >= " + size);
+		}
+		elements[index] = object;
+	}
+
+	/**
+	 * Method to remove the element at a given index
+	 * 
+	 * @param index
+	 */
+	public synchronized void removeElementAt(int index) {
+		if (index >= size) {
+			throw new ArrayIndexOutOfBoundsException(index + " >= " + size);
+		} else if (index < 0) {
+			throw new ArrayIndexOutOfBoundsException(index);
+		}
+		int j = size - index - 1;
+		if (j > 0) {
+			System.arraycopy(elements, index + 1, elements, index, j);
+		}
+		size--;
+		elements[size] = null;
+	}
+
+	/**
+	 * Method to insert element at a given index 
+	 * 
+	 * @param element
+	 * @param index
+	 */
+	public synchronized void insertElementAt(T element, int index) {
+		if (index >= size) {
+			throw new ArrayIndexOutOfBoundsException(index + " >= " +
+					size);
+		}
+		ensureCapacity(size + 1);
+		System.arraycopy(elements, index, elements, index + 1, size - index);
+		elements[index] = element;
+		size++;
+	}
+
+	/**
+	 * Method to add element to vector
+	 * 
+	 * @param element
+	 */
+	public synchronized void addElement(T element) {
+		ensureCapacity(size + 1);
+		elements[size++] = element;
+	}
+
+	/**
+	 * Method to get a element at given index 
+	 * 
+	 * @param index
+	 * @return {@link T}
+	 */
+	public synchronized T get(int index) {
+		if (index >= size) {
+			throw new ArrayIndexOutOfBoundsException(index);
+		}
+		return elementData(index);
+	}
+
+	/**
+	 * Method to ensure capacity
+	 * 
+	 * @param newSize
+	 */
+	private void ensureCapacity(int newSize) {
+		if (newSize >= size) {
+			/* If capacity increment is given, use that else double the size */
+			if (capacityIncrement > 0) {
+				System.arraycopy(elements, 0, elements, size, size + capacityIncrement);
+			} else {
+				System.arraycopy(elements, 0, elements, size, size * 2);
+			}
+		}
+	}
+
+	/**
+	 * Method to return a type casted value at given index
+	 * 
+	 * @param index
+	 * @return {@link T}
+	 */
+	@SuppressWarnings("unchecked")
+	T elementData(int index) {
+		return (T) elements[index];
+	}
 
 }

test/com/deepak/data/structures/Utils/StringUtilsTest.java

@@ -1,5 +1,5 @@
 /**
- * Data-Structures-in-Java
+ * Data-Structures-In-Java
  * StringUtilsTest.java
  */
 package com.deepak.data.structures.Utils;

test/com/deepak/data/structures/Vector/CustomVectorTest.java

@@ -0,0 +1,15 @@
+/**
+ * Data-Structures-In-Java
+ * CustomVectorTest.java
+ */
+package com.deepak.data.structures.Vector;
+
+/**
+ * Test cases for custom vector
+ * 
+ * @author Deepak
+ */
+public class CustomVectorTest {
+
+	
+}