Merge pull request #260 from Gourav-s12/master

Create BasicQueue.java

Author: SarthakKeshari

Data Structure/Queue/Basic Queue/BasicQueue.java

@@ -0,0 +1,121 @@
+/*Queue is an abstract data structure, somewhat similar to Stacks. 
+Unlike stacks, a queue is open at both its ends. One end is always
+used to insert data (enqueue) and the other is used to remove data
+(dequeue). Queue follows First-In-First-Out methodology, i.e., the
+data item stored first will be accessed first.*/
+
+// this is the implementation of a basic queue 
+
+import java.util.Arrays;
+import java.util.Scanner;
+class QueUe{
+    
+    int[] Qarray;
+    int size;
+    int front,rear;
+    
+    QueUe(int capacity){
+        size=capacity;
+        Qarray = new int[capacity];//creating a queue as a array
+        rear=-1;// initializing rear
+        front=-1;//initializing front
+	   //queue is empty at first 
+     }
+    
+    void display(){
+        System.out.println(Arrays.toString(Qarray)); //print the queue
+    }
+    
+    void value(){
+        System.out.println("front:"+front+"\t rare:"+rear); //to see the current rear & front
+    }
+    
+    void peek()
+	{
+		if (isEmpty()) 
+		{
+			System.out.println("Queue empty!");//if queue empty-> no element to peek
+			return;
+		}
+		 System.out.println("peek value is "+Qarray[front]);//peeking the front value
+	}
+	
+    void enqueue(int val){
+        if (isFull())
+		{
+			System.out.println("queue is full!");
+			return; //can not enter element if queue is full
+		}
+        if(rear==-1){
+            front++; //for 1st element put in queue from queue were empty 
+        }
+		System.out.println("Adding " + val);
+
+		rear++ ; //adding new element in rear -> rear++
+		Qarray[rear] = val; //putting the value
+    }
+    
+    void dequeue()
+	{
+		// check for queue underflow
+		if (isEmpty())
+		{
+			System.out.println("queue is empty");
+			return; // if queue is empty -> no element to delete 
+		}
+
+		System.out.println("Deleting " + Qarray[front]);
+        if(front==rear){
+            front=-1;
+            rear=-1;//when only 1 element was in queue , now deleted
+            return; //now queue is empty 
+        }
+		front++; //deleting element-> front ++
+	}
+	
+	Boolean isFull()
+	{
+		return (rear==size-1); // check if queue is full
+	}
+	
+	Boolean isEmpty()
+	{
+		return (front==-1); // check if queue is empty 
+	}
+}
+class BasicQueue { 
+
+    public static void main(String[] args) 
+    { 
+        QueUe que = new QueUe(4);
+
+	   //just some random queue function sequence 
+		que.enqueue(5);
+	        que.peek();
+		que.dequeue();
+		que.peek();
+		que.enqueue(20);
+		que.peek();
+		que.enqueue(4);
+		que.value();
+		que.enqueue(17);
+		que.enqueue(9);
+		
+		if (que.isFull())
+			System.out.println("Queue Is full");
+			
+		que.peek();
+		que.dequeue();
+		que.dequeue();
+		que.peek();
+
+		System.out.println("Queue size is " + que.size);
+
+		que.dequeue();
+		que.dequeue();
+		
+		if (que.isEmpty())
+			System.out.println("Queue Is Empty");
+
+    } 
+}