StackPriority.java

import java.util.ArrayList;
import java.util.Collections;
import java.util.*;

public class PriorityStack {

    ArrayList <Job> stack = new ArrayList <Job>();

    // Methods
    public int size() {
        return stack.size();
    }

    public boolean empty() {

        if(stack.size() == 0) {
            return true;
        }
        else {
            return false;
        }

    }

    public double getMedianPriority() {
        //double[] priorities = new double[stack.size()];
        ArrayList <Double> priorities = new ArrayList <Double>();

        if(stack.size() %2 != 0) {
            for(int i=0; i<stack.size(); i++) {
                priorities.add(i, stack.get(i).priority);
                Collections.sort(priorities);
                int index = (stack.size() + 1) / 2;
                return priorities.get(index);
            }

        }

        else {
            for(int i=0; i<stack.size(); i++) {
                priorities.add(i, stack.get(i).priority);
                Collections.sort(priorities);
                int index1 = stack.size() / 2;
                int index2 = index1 + 1;
                double averagePriority = 0.5 * (priorities.get(index1) + priorities.get(index2));
                return averagePriority;
            }
        }

    }

    public boolean increasePriority(int p) {

        if(p > 0){
            if(size() != 0) {
                for(int i=0; i<stack.size(); i++) {
                    stack.get(i).setPriority(stack.get(i).priority + p);
                }
            }
            return true;
        }
        else {
            return false;
        }
    }

    public void push(Job j) {
        stack.add(j);
    }

    public Job pop() {
        ArrayList <Double> priorities = new ArrayList <Double>();
        for(int i=0; i<stack.size(); i++) {
            priorities.add(i, stack.get(i).priority);
        }
        Collections.sort(priorities);

        // I find the maxPriority
        int index = priorities.size() - 1;
        double maxPriority = priorities.get(index);

        // 3 cases
        if(priorities.size() == 0) {
            System.out.println("Error! ArrayList stack is empty!");
            return new Job(-1000, "Error");
        }

        else if(priorities.size() == 1) {
            Job temp = stack.get(0);
            stack.remove(stack.get(0));
            return temp;
        }

        // Now, I check if there is another priority = maxPriority
        else {
            ArrayList <Job> sameMaxPriority = new ArrayList <Job>();
            for(int i=0; i<stack.size(); i++) {
                if(stack.get(i).priority == maxPriority) {
                    sameMaxPriority.add(stack.get(i));
                }
            }

            Job temp = sameMaxPriority.get(sameMaxPriority.size() - 1);
            stack.remove(temp);
            return temp;
        }



    }




}