HashMap implementation in Java

Author: amitbansal7

Diff for: 16.Hash Map/HashMap.java

@@ -0,0 +1,81 @@
+import java.util.ArrayList;
+import java.util.List;
+public class HashMap<Key, Value> {
+
+	public class Node<Key, Value> {
+		Key key;
+		Value value;
+
+		Node<Key, Value> next;
+
+		public Node(Key k, Value v) {
+			this.key = k;
+			this.value = v;
+			this.next = null;
+		}
+	}
+
+	List<Node<Key, Value> > Map;
+	private int N;
+
+	public HashMap(int n) {
+		N = n;
+		Map = new ArrayList<Node<Key, Value> >(N + 1);
+
+		for (int i = 0; i < n; i++)
+			Map.add(null);
+
+	}
+
+	public void put(Key k, Value v) {
+		int loc = (Math.abs(k.hashCode())) % N;
+
+		Node<Key, Value> newNode = new Node<Key, Value>(k, v);
+		newNode.next = Map.get(loc);
+		Map.set(loc, newNode);
+	}
+
+	public Value get(Key k) {
+		int loc = Math.abs(k.hashCode()) % N;
+
+		Node<Key, Value> crawl = Map.get(loc);
+		while (crawl != null) {
+			if (crawl.key == k)
+				return crawl.value;
+			crawl = crawl.next;
+		}
+
+		return null;
+	}
+
+	public boolean contains(Key k) {
+		int loc = Math.abs(k.hashCode()) % N;
+
+		Node<Key, Value> crawl = Map.get(loc);
+		while (crawl != null) {
+			if (crawl.key == k)
+				return true;
+			crawl = crawl.next;
+		}
+		return false;
+	}
+
+	public static void main(String[] args) {
+		HashMap <String, Integer> Map = new HashMap<>(5);
+
+		Map.put("abc", 123);
+		Map.put("brt", 345);
+		Map.put("cio", 678);
+
+		if (Map.contains("brt") == true)
+			System.out.println(Map.get("brt"));
+		else
+			System.out.println("Key doesn't exists");
+
+		if (Map.contains("ger") == true)
+			System.out.println(Map.get("ger"));
+		else
+			System.out.println("Key doesn't exists");
+
+	}
+}