Add CustomLinkedList as a linked list

Author: zevolution

src/main/java/br/com/zevolution/datastructure/linkedlist/CustomLinkedList.java

@@ -0,0 +1,103 @@
+package br.com.zevolution.datastructure.linkedlist;
+
+import java.util.NoSuchElementException;
+
+public class CustomLinkedList {
+	
+	private Node first = null;
+	private Node last = null;
+	private int totalElements = 0;
+	
+	public void addFirst(Object element) {
+		Node node = new Node(element, this.first);
+		this.first = node;
+		
+		if (this.totalElements == 0) {
+			this.last = this.first;
+		}
+		
+		this.totalElements++;
+	}
+	
+	public void add(Object element) {
+		if (this.totalElements == 0) {
+			this.addFirst(element);
+		} else {
+			Node node = new Node(element, null);
+			this.last.setNext(node);
+			this.last = node;
+			this.totalElements++;
+		}
+	}
+	
+	public void add(int position, Object element) {
+		if (!this.isValidContentPosition(position)) 
+			throw new UnoccupiedPosition();
+		
+		if (position == 0) {
+			this.addFirst(element);
+		} else if (position == this.totalElements) {
+			this.add(element);
+		} else {
+			Node previousNode = this.getNode(position - 1);
+			Node node = new Node(element, previousNode.getNext());
+			previousNode.setNext(node);
+			this.totalElements++;
+		}
+	}
+	
+	public void removeFirst() {
+		if (this.totalElements == 0) 
+			throw new NoSuchElementException();
+		
+		this.first = this.first.getNext();
+		this.totalElements--;
+		
+		if (this.totalElements == 0) { 
+			this.last = null;
+		}
+	}
+
+	public Object get(int position) {
+		return this.getNode(position).getElement();
+	}
+	
+	public int size() {
+		return this.totalElements;
+	}
+	
+	@Override
+	public String toString() {
+		if (this.totalElements == 0) return "[]";
+
+		Node node = this.first;
+		
+		StringBuilder builder = new StringBuilder("[");
+		
+		for (int i = 0; i < this.totalElements -1; i++) {
+			builder.append(node.getElement()).append(", ");
+			node = node.getNext();
+		}
+		
+		builder.append(node.getElement()).append("]");
+		
+		return builder.toString(); 
+	}
+	
+	private boolean isValidContentPosition(int position) {
+		return position >= 0 && position < this.totalElements;
+	}
+	
+	private Node getNode(int position) {
+		if (!this.isValidContentPosition(position)) 
+			throw new UnoccupiedPosition();
+		
+		Node node = this.first;
+		for (int i = 0; i < position; i++) {
+			node = node.getNext();
+		}
+		return node;
+	}
+	
+
+}

src/main/java/br/com/zevolution/datastructure/linkedlist/InvalidPosition.java

@@ -0,0 +1,15 @@
+package br.com.zevolution.datastructure.linkedlist;
+
+public class InvalidPosition extends RuntimeException {
+
+	private static final long serialVersionUID = -3536404610449816152L;
+	
+	public InvalidPosition() {
+		super("Invalid position");
+	}
+	
+	public InvalidPosition(String message) {
+		super(message);
+	}
+
+}

src/main/java/br/com/zevolution/datastructure/linkedlist/Node.java

@@ -0,0 +1,26 @@
+package br.com.zevolution.datastructure.linkedlist;
+
+public class Node {
+	
+	private Node next;
+	private Object element;
+	
+	public Node(Object element, Node next) {
+		this.element = element;
+		this.next = next;
+	}
+
+	public Node getNext() {
+		return next;
+	}
+
+	public void setNext(Node next) {
+		this.next = next;
+	}
+
+	public Object getElement() {
+		return element;
+	}
+	
+	
+}

src/main/java/br/com/zevolution/datastructure/linkedlist/UnoccupiedPosition.java

@@ -0,0 +1,12 @@
+package br.com.zevolution.datastructure.linkedlist;
+
+public class UnoccupiedPosition extends InvalidPosition {
+
+	private static final long serialVersionUID = -2300538444121627252L;
+	
+	public UnoccupiedPosition() {
+		super("There is no value in this position");
+	}
+
+	
+}

src/test/java/br/com/zevolution/datastructure/linkedlist/CustomLinkedListTest.java

@@ -0,0 +1,96 @@
+package br.com.zevolution.datastructure.linkedlist;
+
+import static org.junit.Assert.*;
+
+import java.util.NoSuchElementException;
+
+import org.junit.Test;
+
+public class CustomLinkedListTest {
+
+	@Test
+	public void should_Contain_OneRecordInCustomLinkedList() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("José Lucas");
+		
+		assertEquals(1, linkedList.size());
+	}
+	
+	@Test
+	public void should_Contain_TwoRecordsInCustomLinkedList() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("Beatriz");
+		linkedList.add("José Lucas");
+		
+		assertEquals(2, linkedList.size());
+	}
+	
+	@Test
+	public void should_MakeSure_ObjectPosition() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("Beatriz");
+		linkedList.add("José Lucas");
+		linkedList.add(0, "Laura");
+		
+		assertEquals("Laura", linkedList.get(0));
+		assertEquals("Beatriz", linkedList.get(1));
+		assertEquals("José Lucas", linkedList.get(2));
+	}
+	
+	@Test
+	public void should_MakeSure_AddFirst_ObjectPosition() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("Beatriz");
+		linkedList.add("José Lucas");
+		linkedList.addFirst("Laura");
+		
+		assertEquals("Laura", linkedList.get(0));
+		assertEquals("Beatriz", linkedList.get(1));
+		assertEquals("José Lucas", linkedList.get(2));
+	}
+	
+	@Test
+	public void should_MakeSure_RemoveFirst_ObjectPosition() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("Beatriz");
+		linkedList.add("Laura");
+		linkedList.addFirst("José Lucas");
+		
+		linkedList.removeFirst();
+		
+		assertNotEquals("José Lucas", linkedList.get(0));
+		assertEquals("Beatriz", linkedList.get(0));
+		assertEquals(2, linkedList.size());
+	}
+	
+	@Test
+	public void should_Be_Empty() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("Beatriz");
+		linkedList.add("José Lucas");
+		linkedList.add("Laura");
+		
+		for (int i = linkedList.size(); i > 0; i--) {
+			linkedList.removeFirst();
+		}
+		
+		assertEquals(0, linkedList.size());
+	}
+	
+	
+	@Test(expected = UnoccupiedPosition.class)
+	public void should_ThrowException_When_UnoccupiedPosition() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		linkedList.add("zevolution");
+		
+		linkedList.add(1, "noitulovez");;
+	}
+	
+	@Test(expected = NoSuchElementException.class)
+	public void should_ThrowException_When_NoSuchElement() {
+		CustomLinkedList linkedList = new CustomLinkedList();
+		
+		linkedList.removeFirst();
+	}	
+
+}