Update PriorityQueues.java

Author: yanglbme

DataStructures/Queues/PriorityQueues.java

@@ -1,127 +1,128 @@
 /**
  * This class implements a PriorityQueue.
- * 
+ * <p>
  * A priority queue adds elements into positions based on their priority.
  * So the most important elements are placed at the front/on the top.
  * In this example I give numbers that are bigger, a higher priority.
  * Queues in theory have no fixed size but when using an array
  * implementation it does.
- * 
- * @author Unknown
  *
  */
-class PriorityQueue{
-	/** The max size of the queue */
-	private int maxSize;
-	/** The array for the queue */
-	private int[] queueArray;
-	/** How many items are in the queue */
-	private int nItems;
+class PriorityQueue {
+    /**
+     * The max size of the queue
+     */
+    private int maxSize;
+    /**
+     * The array for the queue
+     */
+    private int[] queueArray;
+    /**
+     * How many items are in the queue
+     */
+    private int nItems;
 
-	/**
-	 * Constructor
-	 * 
-	 * @param size Size of the queue
-	 */
-	public PriorityQueue(int size){
-		maxSize = size;
-		queueArray = new int[size];
-		nItems = 0;
-	}
+    /**
+     * Constructor
+     *
+     * @param size Size of the queue
+     */
+    public PriorityQueue(int size) {
+        maxSize = size;
+        queueArray = new int[size];
+        nItems = 0;
+    }
 
-	/**
-	 * Inserts an element in it's appropriate place
-	 * 
-	 * @param value Value to be inserted
-	 */
-	public void insert(int value){
-		if(nItems == 0){
-			queueArray[0] = value;
-			nItems++;
-		}
-		else if(isFull()){	//does not insert value when the queue is full
-			System.out.println("Queue is full");
-		}
-		else{
-			int j = nItems;
-			while(j > 0 && queueArray[j-1] > value){
-				queueArray[j] = queueArray[j-1]; //Shifts every element up to make room for insertion
-				j--;
-			}
-			queueArray[j] = value; //Once the correct position is found the value is inserted
-			nItems++;
-		}
-	}
+    /**
+     * Inserts an element in it's appropriate place
+     *
+     * @param value Value to be inserted
+     */
+    public void insert(int value) {
+        if (isFull()) {
+            throw new RuntimeException("Queue is full");
+        }
+        if (nItems == 0) {
+            queueArray[0] = value;
+        } else {
+            int j = nItems;
+            while (j > 0 && queueArray[j - 1] > value) {
+                queueArray[j] = queueArray[j - 1]; // Shifts every element up to make room for insertion
+                j--;
+            }
+            queueArray[j] = value; // Once the correct position is found the value is inserted
+        }
+        nItems++;
+    }
 
-	/**
-	 * Remove the element from the front of the queue
-	 * 
-	 * @return The element removed
-	 */
-	public int remove(){
-		return queueArray[--nItems];
-	}
+    /**
+     * Remove the element from the front of the queue
+     *
+     * @return The element removed
+     */
+    public int remove() {
+        return queueArray[--nItems];
+    }
 
-	/**
-	 * Checks what's at the front of the queue
-	 * 
-	 * @return element at the front of the queue
-	 */
-	public int peek(){
-		return queueArray[nItems-1];
-	}
+    /**
+     * Checks what's at the front of the queue
+     *
+     * @return element at the front of the queue
+     */
+    public int peek() {
+        return queueArray[nItems - 1];
+    }
 
-	/**
-	 * Returns true if the queue is empty
-	 * 
-	 * @return true if the queue is empty
-	 */
-	public boolean isEmpty(){
-		return(nItems == 0);
-	}
+    /**
+     * Returns true if the queue is empty
+     *
+     * @return true if the queue is empty
+     */
+    public boolean isEmpty() {
+        return (nItems == 0);
+    }
 
-	/**
-	 * Returns true if the queue is full
-	 * 
-	 * @return true if the queue is full
-	 */
-	public boolean isFull(){
-		return(nItems == maxSize);
-	}
+    /**
+     * Returns true if the queue is full
+     *
+     * @return true if the queue is full
+     */
+    public boolean isFull() {
+        return (nItems == maxSize);
+    }
 
-	/**
-	 * Returns the number of elements in the queue
-	 * 
-	 * @return number of elements in the queue
-	 */
-	public int getSize(){
-		return nItems;
-	}
+    /**
+     * Returns the number of elements in the queue
+     *
+     * @return number of elements in the queue
+     */
+    public int getSize() {
+        return nItems;
+    }
 }
 
 /**
  * This class implements the PriorityQueue class above.
- * 
- * @author Unknown
  *
+ * @author Unknown
  */
-public class PriorityQueues{
-	/**
-	 * Main method
-	 * 
-	 * @param args Command Line Arguments
-	 */
-	public static void main(String args[]){
-		PriorityQueue myQueue = new PriorityQueue(4);
-		myQueue.insert(10);
-		myQueue.insert(2);
-		myQueue.insert(5);
-		myQueue.insert(3);
-		//[2, 3, 5, 10] Here higher numbers have higher priority, so they are on the top
+public class PriorityQueues {
+    /**
+     * Main method
+     *
+     * @param args Command Line Arguments
+     */
+    public static void main(String[] args) {
+        PriorityQueue myQueue = new PriorityQueue(4);
+        myQueue.insert(10);
+        myQueue.insert(2);
+        myQueue.insert(5);
+        myQueue.insert(3);
+        // [2, 3, 5, 10] Here higher numbers have higher priority, so they are on the top
 
-		for(int i = 3; i>=0; i--)
-			System.out.print(myQueue.remove() + " "); //will print the queue in reverse order [10, 5, 3, 2]
+        for (int i = 3; i >= 0; i--)
+            System.out.print(myQueue.remove() + " "); // will print the queue in reverse order [10, 5, 3, 2]
 
-		//As you can see, a Priority Queue can be used as a sorting algotithm
-	}
+        // As you can see, a Priority Queue can be used as a sorting algotithm
+    }
 }