PriorityQueue Queue
PriorityQueue extends AbstactQueue. PriorityQueue is a type of queue but not provide the FIFO facility to its elements. It not allows the null elements. A PriorityQueue is like a normal queue but each element has a priority associated with it.
Example
package com.w3spoint;
public class Test {
@SuppressWarnings("rawtypes")
private Comparable[] pQueue;
private int index;
public Test(int capacity){
pQueue = new Comparable[capacity];
}
public void insert(Comparable item ){
if(index == pQueue.length){
System.out.println("Overflow state.");
return;
}
pQueue[index] = item;
index++;
System.out.println("Adding element: "+item);
}
@SuppressWarnings("unchecked")
public Comparable remove(){
if(index == 0){
System.out.println("Underflow state.");
return null;
}
int maxIndex = 0;
for (int i=1; i<index; i++) {
if (pQueue[i].compareTo (pQueue[maxIndex]) > 0) {
maxIndex = i;
}
}
Comparable result = pQueue[maxIndex];
System.out.println("removing: "+result);
index--;
pQueue[maxIndex] = pQueue[index];
return result;
}
public static void main(String args[]){
try {
Test pQueue = new Test(3);
pQueue.insert(15);
pQueue.insert(8);
pQueue.insert(12);
pQueue.remove();
pQueue.remove();
} catch (Exception e) {
e.printStackTrace();
}
}
} |
package com.w3spoint; public class Test {
@SuppressWarnings("rawtypes")
private Comparable[] pQueue;
private int index;
public Test(int capacity){
pQueue = new Comparable[capacity];
}
public void insert(Comparable item ){
if(index == pQueue.length){
System.out.println("Overflow state.");
return;
}
pQueue[index] = item;
index++;
System.out.println("Adding element: "+item);
}
@SuppressWarnings("unchecked")
public Comparable remove(){
if(index == 0){
System.out.println("Underflow state.");
return null;
}
int maxIndex = 0;
for (int i=1; i<index; i++) {
if (pQueue[i].compareTo (pQueue[maxIndex]) > 0) {
maxIndex = i;
}
}
Comparable result = pQueue[maxIndex];
System.out.println("removing: "+result);
index--;
pQueue[maxIndex] = pQueue[index];
return result;
}
public static void main(String args[]){
try {
Test pQueue = new Test(3);
pQueue.insert(15);
pQueue.insert(8);
pQueue.insert(12);
pQueue.remove();
pQueue.remove();
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output
Adding element: 15
Adding element: 8
Adding element: 12
removing: 15
removing: 12 |
Adding element: 15
Adding element: 8
Adding element: 12
removing: 15
removing: 12