How to save Jobs with different priority level in a Queue?

Question

Hi, Friends,
I have a set of Job (see below) objects.
I would make a queue: if they have the save priority level, first in and first out. this is easy to do by ArrayList. however, If they have different priority level, I would like make the Jobs with the highest level first out.
How can I implemented this idea in Java?
Regards,
Youbin
public class Job {
private short _priorityLevel = 0;
public void setPriorityLevel(short priorityLevel) {
this._priorityLevel = priorityLevel;
public short getPriorityLevel() {
return _priorityLevel;

Answer 1

Hi,
Here is my test code, it works:
public class Job implements Comparable{
private int _priorityLevel=0;
private String _jobDescription=null;
public Job() {
public void setPriorityLevel(int priorityLevel) {
this._priorityLevel=priorityLevel;
public int getPriorityLevel() {
return this._priorityLevel;
public void setJobDescription(String jobDescription) {
this._jobDescription=jobDescription;
public String getJobDescription() {
return this._jobDescription;
public int compareTo(Object obj) {
return (this._priorityLevel-((Job)obj)._priorityLevel);
import java.util.LinkedList;
import java.util.Iterator;
import java.util.Collections;
import java.util.Collection;
public class test {
public test() {
public static void main(String[] args) {
Job job1 = new Job();
job1.setJobDescription("Job1");
job1.setPriorityLevel(2);
Job job2 = new Job();
job2.setJobDescription("Job2");
job2.setPriorityLevel(2);
Job job3 = new Job();
job3.setJobDescription("Job3");
job3.setPriorityLevel(2);
Job job4 = new Job();
job4.setJobDescription("Job4");
job4.setPriorityLevel(1);
Job job5 = new Job();
job5.setJobDescription("Job5");
job5.setPriorityLevel(1);
Job job6 = new Job();
job6.setJobDescription("Job6");
job6.setPriorityLevel(1);
LinkedList linkedList = new LinkedList();
linkedList.addLast(job1);
linkedList.addLast(job2);
linkedList.addLast(job4);
Iterator ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
System.out.println("---------");
Collections.sort(linkedList);
ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
System.out.println("---------");
linkedList.addLast(job3);
ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
System.out.println("---------");
Collections.sort(linkedList);
ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
System.out.println("---------");
linkedList.addLast(job5);
linkedList.addLast(job6);
ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
System.out.println("---------");
Collections.sort(linkedList);
ite=linkedList.iterator();
while (ite.hasNext()) {
System.out.println(((Job)ite.next()).getJobDescription());
}