Queue data structure
public class Queue {
private int maxSize;
private long[] queArray;
private int front;
private int rear;
private int nItems;
public Queue(int s) {
maxSize = s;
queArray = new long[maxSize];
front = 0;
rear = -1;
nItems = 0;
}
// put item at end of a queue
public void insert(long j) {
if (rear == maxSize - 1) // deal with wraparound
rear = -1;
queArray[++rear] = j; // increment rear and insert
nItems++;
}
// take item from front of queue
public long remove() {
long temp = queArray[front++]; // get value and incr front
if (front == maxSize) // deal with wraparound
front = 0;
nItems--; // one less item
return temp;
}
public long peekFront() {
return queArray[front];
}
public boolean isEmpty() {
return (nItems == 0);
}
public boolean isFull() {
return (nItems == maxSize);
}
public int size() {
return nItems;
}
public static void main(String[] args) {
Queue theQueue = new Queue(5); // queue holds 5 items
theQueue.insert(10);
theQueue.insert(20);
theQueue.insert(30);
theQueue.insert(40);
theQueue.remove();
theQueue.remove();
theQueue.remove();
theQueue.insert(50);
theQueue.insert(60); // (wraps around)
theQueue.insert(70);
theQueue.insert(80);
while (!theQueue.isEmpty()) {
long n = theQueue.remove(); // (40, 50, 60, 70, 80)
System.out.print(n);
System.out.print(" ");
}
System.out.println("");
}
}
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