Question

I am trying to make a linked list queue and I am trying to use the display method I made just to see if its working but when I run it nothing is displayed please help. Also the newPlane boolean was made just so I can randomly decide if the plane is going to join the queue or not.

public class PlaneSimulation {

    public static void main(String[] args) {
        int landTime = 2;
        int takeoffTime = 3;
        int avgArrivalInterval = 3;
        int avgDepartInterval = 3;
        int totalTime = 65;
//regular queue takeOffQueue.insert()
        LinkedList.Queue takeOffQueue = new LinkedList.Queue();
        for (int i = 0; i < totalTime; i++) {
            if (i % 3 == 0) {
                if (newPlane())
                    takeOffQueue.insert();
            }
        }
        takeOffQueue.display();
    }

    public static boolean newPlane() {
        if (Math.random() < 1 / 2)
            return true;
        else {
            return false;
        }

    }

    static class Node {
        int data;
        Node next;

        public Node(int key) {
            data = key;
            next = null;
        }

        public void displayNode() {
            System.out.println("item" + data);
        }
    }

    static class LinkedList {
        Node first;

        public LinkedList() {
            first = null;
        }

        public void insert(int z) {
            Node newNode = new Node(z);

            if (first == null) {
                first = newNode;
                return;
            }
            Node tempNode = first;
            while (tempNode.next != null) {
                tempNode = tempNode.next;
            }
            tempNode.next = newNode;
        }

        public Node remove() {
            Node temp = first;
            first = first.next;
            return temp;
        }

        public void display() {
            Node tempNode = first;
            while (tempNode != null) {
                tempNode.displayNode();
                tempNode = tempNode.next;
            }
            System.out.println();
        }

        static class Queue {
            LinkedList list = new LinkedList();
            private int z;

            public void insert() {
                list.insert(z);
            }

            public void remove() {
                list.remove();
            }

            public void display() {
                list.display();

            }

        }
    }}

Answer 1

Solution:

In your code, the newPlane() always returns false, because it is false, the i values are not getting inserted. I have made a few chages to the code. Below is the modified code.

PlaneSimulation.java:

public class PlaneSimulation {

public static void main(String[] args) {
int landTime = 2;
int takeoffTime = 3;
int avgArrivalInterval = 3;
int avgDepartInterval = 3;
int totalTime = 65;
//regular queue takeOffQueue.insert()
LinkedList.Queue takeOffQueue = new LinkedList.Queue();
for (int i = 0; i < totalTime; i++) {
if (i % 3 == 0) {
               boolean flag = newPlane();
if(!flag) {
takeOffQueue.insert(i);
               }
}
}
takeOffQueue.display();
}

public static boolean newPlane() {
       double a = Math.random();
if (a < 1 / 2) {
System.out.println(a);
return true;
       }
else {
return false;
}

}

static class Node {
int data;
Node next;

public Node(int key) {
data = key;
next = null;
}

public void displayNode() {
System.out.println("Item: " + data);
}
}

static class LinkedList {
Node first;

public LinkedList() {
first = null;
}

public void insert(int z) {
Node newNode = new Node(z);

if (first == null) {
first = newNode;
return;
}
Node tempNode = first;
while (tempNode.next != null) {
tempNode = tempNode.next;
}
tempNode.next = newNode;
}

public Node remove() {
Node temp = first;
first = first.next;
return temp;
}

public void display() {
Node tempNode = first;
while (tempNode != null) {
tempNode.displayNode();
tempNode = tempNode.next;
}
System.out.println();
}

static class Queue {
LinkedList list = new LinkedList();

public void insert(int z) {
list.insert(z);
}

public void remove() {
list.remove();
}

public void display() {
list.display();

}

}
}}

output:

Eile Edit Search View Document Project Bid Iools Help New Open Save Save AllRevert CloseBack Forward Compile Build Execute Color Chooser Find Jump to Quit Symbols Documents Codelam.javaX TextAnalyser.cX Sample1.txt X Purse.java X PurseAppjava X PlaneSimulaionjava Queue.java X LinkedListjava Nodejava X 曰, Classes 曰, planesimulati E , LinkedList [ o LinkedLis 曰, Queue [ oP dsplay o insert list [8 remow o dsplay [7 first [48] o insert [5 remove [ Item : 9 Item: 3 Item: 6 Item: 9 Item: 12 Item: 15 Item: 18 Item: 21 Item: 24 Item: 27 Item: 30 Item: 33 Item: 36 Item: 39 Item: 42 Item: 45 Item: 48 Item: 51 Item: 54 Item: 57 Item: 60 Item: 63 E Node [33] Node [3 data [34 d dsplayNo next [35 main [3] o newPlane (program exited with code: e) Javac "P Compiler Compilati Messages Scribble ress any key to continue 1 file saved. 1) 4:20 PM 모 ^