Implementation of Set

Author: deepak-malik

src/com/deepak/data/structures/Set/ArrayBasedSet.java

@@ -0,0 +1,134 @@
+/**
+ * Data-Structures-And-Algorithms-in-Java
+ * ArrayBasedSet.java
+ */
+package com.deepak.data.structures.Set;
+
+/**
+ * Class implementing Set based on Array
+ * @author Deepak
+ *
+ * @param <T>
+ */
+public class ArrayBasedSet<T> {
+
+	/**
+	 * Array of object
+	 */
+	private Object arrayElements[];
+
+	/**
+	 * Variable to keep track of Set size
+	 */
+	private int size = 0;
+
+	/**
+	 * Default capacity of the Set
+	 */
+	private int DEFAULT_CAPACITY = 8;
+
+	/**
+	 * Constructor to create a new Set
+	 * based on capacity
+	 * @param capacity
+	 */
+	public ArrayBasedSet(int capacity) {
+		arrayElements = new Object[capacity];
+	}
+
+	/**
+	 * Constructor to create a new Set 
+	 * based on elements
+	 * @param elements
+	 */
+	public ArrayBasedSet(T[] elements) {
+		arrayElements = elements;
+		size = arrayElements.length;
+	}
+
+	/**
+	 * Method to add a element to Set
+	 * @param element
+	 */
+	public void addElement(T element) {
+		if (!contains(element)) {
+			if (size == arrayElements.length) {
+				incrementArraySize();
+			}
+			arrayElements[size++] = element;
+		}
+	}
+
+	/**
+	 * Method to check if element exists in Stack
+	 * @param element
+	 * @return {@link boolean}
+	 */
+	public boolean contains(T element) {
+		if (null == element) {
+			for (int i = 0; i < size; i++) {
+				if (null == arrayElements[i]) {
+					return true;
+				}
+			}
+		} else {
+			for (int i = 0; i < size; i++) {
+				if (element.equals(arrayElements[i])) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Method to check the size of Set
+	 * @return {@link int}
+	 */
+	public int size() {
+		return size;
+	}
+
+	/**
+	 * Method to check if Set is empty
+	 * @return {@link boolean}
+	 */
+	public boolean isEmpty() {
+		return size() == 0;
+	}
+
+	/**
+	 * Method to clear all the elements in Set
+	 */
+	public void clear() {
+		arrayElements = new Object[DEFAULT_CAPACITY];
+		size = 0;
+	}
+
+	/**
+	 * toString implementation
+	 */
+	public String toString() {
+		if (null == arrayElements || arrayElements.length == 0) {
+			return "[EMPTY]";
+		} else {
+			String toStr = "[";
+			for (int i = 0; i < arrayElements.length; i++) {
+				toStr += arrayElements[i] + "”,";
+			}
+			toStr += "”]";
+			return toStr;
+		}
+	}
+
+	/**
+	 * Method to increment the size when Set is full
+	 */
+	private void incrementArraySize() {
+		Object[] tempArray = arrayElements;
+		int tempSize = size * 2;
+		arrayElements = new Object[tempSize];
+		System.arraycopy(tempArray, 0, arrayElements, 0, size);
+	}
+
+}

src/com/deepak/data/structures/Stack/ArrayBasedStack.java

@@ -6,6 +6,9 @@
 
 import java.util.NoSuchElementException;
 
+/**
+ * Class implementing Stack based on Array
+ */
 public class ArrayBasedStack {
 
 	/**

test/com/deepak/data/structures/Set/ArrayBasedSetTest.java

@@ -0,0 +1,53 @@
+/**
+ * Data-Structures-And-Algorithms-in-Java
+ * ArrayBasedSetTest.java
+ */
+package com.deepak.data.structures.Set;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Test cases for Set
+ *  
+ * @author Deepak
+ */
+public class ArrayBasedSetTest {
+
+	/**
+	 * Test case to check the insertion
+	 */
+	@Test
+	public void testInsertionInSet() {
+		ArrayBasedSet<String> set = new ArrayBasedSet<>(5);
+		Assert.assertTrue(set.size() == 0);
+		set.addElement("One");
+		set.addElement("Two");
+		set.addElement("Three");
+		Assert.assertTrue(set.size() == 3);
+		set.addElement("Four");
+		Assert.assertTrue(set.size() == 4);
+		/* Trying to insert Three again. Size should not change and operation should fail */
+		set.addElement("Three"); 
+		Assert.assertTrue(set.size() == 4);
+	}
+
+	/**
+	 * Test case to check other operations on Set
+	 */
+	@Test
+	public void testOtherOperationsOnSet() {
+		ArrayBasedSet<String> set = new ArrayBasedSet<>(5);
+		Assert.assertTrue(set.isEmpty());
+		Assert.assertTrue(set.size() == 0);
+		set.addElement("One");
+		set.addElement("Two");
+		set.addElement("Three");
+		Assert.assertTrue(set.contains("Two"));
+		Assert.assertTrue(set.size() == 3);
+		set.clear();
+		Assert.assertTrue(set.isEmpty());
+		Assert.assertTrue(set.size() == 0);
+	}
+
+}