// add a delete method to class MyNameQueue !!!!
// demonstrate that it works !!!!
//CIT242 Data Structures
public class QueueApp {

public static void main(String[] args) {
MyNameQueue myQueue = new MyNameQueue();

System.out.println(“Welcome to my Queue.n”);
//populating the queue
myQueue.push(“Jack”, “Haley”);
myQueue.push(“A”, “A”);
myQueue.push(“John”, “Smith”);
myQueue.push(“Winston”, “Churchill”);
myQueue.push(“Nelson”, “Mandela”);
myQueue.push(“Mary”, “Jones”);

System.out.println(“before popping:”);
myQueue.printQueue();
System.out.println(“”);

System.out.println(“do a pop:”);
myQueue.pop();
System.out.println(“”);

System.out.println(“after popping:”);
myQueue.printQueue();
System.out.println(“”);

System.out.println(“count the queue:”);
myQueue.countQueue();
System.out.println(“”);
System.out.println(“”);

System.out.println(“after a listInsert (Walt Disney) :”);
myQueue.listInsert(“Walt”, “Disney”);
myQueue.printQueue();
System.out.println(“”);

}
}

class Entry {

String first;
String last;

public Entry(String first, String last) {
this.first = first;
this.last = last;
}

public String toString() {
//return “Entry{” + “first=” + first + “, last=” + last + ‘}’;
return first + ” ” + last;
}

}

class NODE {

Entry info;
NODE link;

public NODE(Entry info) {
this.info = info;
}

public NODE() {
info = new Entry(“”, “”);
}

}

class MyNameQueue {

NODE top;
NODE last;

public MyNameQueue() {
top = null;

}

public void push(String firstName, String lastName) {
Entry newEntry = new Entry(firstName, lastName);

NODE newRecord = new NODE();
newRecord.info = newEntry;
newRecord.link = null;

if (top == null) {
top = last = newRecord;
} else {
last.link = newRecord; //why?
last = newRecord;
}

}

public void printQueue() {
NODE newTop = top;

while (newTop != null) {
System.out.println(newTop.info.toString());
newTop = newTop.link;

}

}

public NODE pop() {

if (top == null) {
System.out.println(“the queue is empty.”);
return new NODE(); //return null;
} else {
NODE p = top;
top = top.link;
System.out.println(p.info.toString());
//p.link = null; //is this necessary????
return p;
}

}

public void countQueue() {
int i = 0;
NODE p = top;

while (p != null) {
i++;
p = p.link;
}

System.out.printf(“Total items in queue: %d”, i);
}

public void listInsert(String firstName, String lastName) {

Entry newEntry = new Entry(firstName, lastName);
NODE last, next;
next = top;
last = null; // is this necessary???? Yes, you might insert a new NODE before the top

while ((newEntry.last.compareTo(next.info.last) > 0) && (next.link != null)) {
last = next;
next = next.link;
System.out.println(“here”);
}

if (newEntry.last.compareTo(next.info.last) == 0) {
next.info = newEntry; //update
}
else
if (newEntry.last.compareTo(next.info.last) < 0) {
if (last == null) { //if the new entry should be insert before the top
NODE p = new NODE(newEntry);
p.link = top;
top = p;

} else {
last.link = new NODE();
last.link.info = newEntry;
last.link.link = next;
}
}
else {
// NODE temp = next.link; //store the link after next node before insert the new node after the next node
next.link = new NODE();
next.link.info = newEntry;
// next.link.link = temp;
next.link.link = null;
}

}

}