CC-2 : FIFO Queue Using array.

Description:

Create a FIFO Queue using array for storage instead of LinkedList.

Test cases and expected outputs:

Input Parameters	Expected outputs
QueueArray queue=new QueueArray(); queue.add(9); queue.add(14); queue.add(17); queue.add(34); queue.add(21); queue.add(28);	Queue nodes: 9 <- 14 <- 17 <- 34 <- 21 <- 28
queue.remove(); queue.remove(); queue.remove();	Queue nodes: 34 <- 21 <- 28

Pseudocode:

The FIFO Array Queue should instantiate and use a fixed size array for storing data elements. The last index of array at which data element is present also needs to be tracked.

The add() method: it adds input element to the storage array till it is full. Once the array is full, the add() method does not add the element to the array and returns false.

The remove() method: if storage array is empty, return false, else return the first element of the array and shift all data elements in the array left by 1 index.

Code:

public class QueueArray {
	
private int[] queue=new int[10];	
private int lastIdx=-1;
	
public int get() {
	if (lastIdx != -1) {
		return queue[0];
	}
	return Integer.MIN_VALUE;
}

public boolean add(int data){
	if (lastIdx == queue.length-1) {return false;}
	lastIdx++;
	queue[lastIdx]=data;
	return true;
}

public int remove() {
	if (lastIdx == -1) {return Integer.MIN_VALUE;}
	int removedData=queue[0];
	int qIdx=0;
	for (qIdx=0; qIdx < lastIdx; qIdx++) {
			queue[qIdx]=queue[qIdx+1];
	} 
	queue[lastIdx]=0;
	lastIdx--;
	return removedData;
}
}

Click here to download and run code and test cases !

Below fully running code can be copied and run on Eclipse or other Java IDEs. Refer the classname in code below. If the class name below is "A", save the code below to a file named A.java before running it. Be sure to try your own test cases to enhance your understanding ! You can also tweak the code to optimize or add enhancements and custom features.

public class QueueArray {
	
private int[] queue=new int[10];	
private int lastIdx=-1;
	
public int get() {
	if (lastIdx != -1) {
		return queue[0];
	}
	return Integer.MIN_VALUE;
}

public boolean add(int data){
	if (lastIdx == queue.length-1) {return false;}
	lastIdx++;
	queue[lastIdx]=data;
	return true;
}

public int remove() {
	if (lastIdx == -1) {return Integer.MIN_VALUE;}
	int removedData=queue[0];
	int qIdx=0;
	for (qIdx=0; qIdx < lastIdx; qIdx++) {
			queue[qIdx]=queue[qIdx+1];
	} 
	queue[lastIdx]=0;
	lastIdx--;
	return removedData;
}

public int getSize() {
	return lastIdx+1;
}


public void traverse() {
	int qIdx=0;
	for (qIdx=0; qIdx < queue.length; qIdx++) {
			System.out.print(queue[qIdx]);
			if (qIdx < queue.length-1) {System.out.print(",");}
	} 
}

			

public void printQueue() throws Exception {
   	System.out.println();
	System.out.println("**********************************************************");
	System.out.print("Queue Array"+" : ");
	int qIdx=0;
	for (qIdx=0; qIdx < queue.length; qIdx++) {
			System.out.print(queue[qIdx]);
			if (qIdx < queue.length-1) {System.out.print(",");}
	} 
	System.out.println();
	System.out.println("**********************************************************");
	System.out.println();
	Thread.sleep(2000);
	return;
} 
  	
public static void main(String[] args) {
	/* Test Cases give below:	*/
	try {
	QueueArray queue=new QueueArray();
	System.out.print("Add to Queue");
	queue.add(9);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(14);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(17);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(34);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(21);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(28);
	queue.printQueue();
	
	System.out.println("QUEUE ARRAY SIZE "+queue.getSize());
	
	System.out.print("\nRemove from Queue");
	queue.remove();
	queue.printQueue();
	System.out.print("Remove from Queue");
	queue.remove();
	queue.printQueue();
	System.out.print("Remove from Queue");
	
	System.out.println("GET FIRST NODE "+queue.get());
	
	queue.remove();
	queue.printQueue();
	System.out.print("\nRemove from Queue");
	queue.remove();
	queue.printQueue();
	System.out.print("Remove from Queue");
	queue.remove();
	queue.printQueue();
	System.out.print("Remove from Queue");
	queue.remove();
	queue.printQueue();
	
	System.out.println("QUEUE ARRAY SIZE "+queue.getSize());
	System.out.println("\nGET FIRST NODE "+queue.get());
	
	System.out.print("Add to Queue");
	queue.add(99);
	queue.printQueue();
	System.out.print("Add to Queue");
	queue.add(44);
	queue.printQueue();
	
	
	}catch (Exception exception) {
		System.out.print("Exception: "+ exception);
	}
		
}
	
}