Question

can you please explain how to complete all methods in java ?
thanks

/*
Note:   Do not add any additional methods, attributes.
        Do not modify the given part of the program.
        Run your program against the provided Homework2Driver.java for requirements.
*/

/*
Hint:   This Queue implementation will always dequeue from the first element of
        the array i.e, elements[0]. Therefore, remember to shift all elements
        toward front of the queue after each dequeue.
*/

public class QueueArray<T> {
    public static int CAPACITY = 100;
    private final T[] elements;
    private int rearIndex = -1;
   
    public QueueArray() {
    }

    public QueueArray(int size) {
    }
   
    public T dequeue() {

    }
   
    public void enqueue(T info) {

    }
   
    public boolean isEmpty() {
       
    }
   
    public boolean isFull() {
       
    }
   
    public int size() {
       
    }
}

Answer 1

public class QueueArray<T> {
public static int CAPACITY = 100;
private final T[] elements;
private int rearIndex = -1;

public QueueArray() {
       elements = (T[])new Object[CAPACITY];
}

public QueueArray(int size) {
       CAPACITY =size;
elements = (T[])new Object[CAPACITY];
}

public T dequeue() {
if(isEmpty())return null;
else
{
T t = elements[0];
int i=0;
while(i< rearIndex )//moving front
{
elements[i]=elements[i+1];
i++;
}
rearIndex -=1;//decreasing rear index
return t;
}
}

public void enqueue(T info) {
if(!isFull()){
elements[ rearIndex +1]=info;
rearIndex +=1;
}
}

public boolean isEmpty() {
if( rearIndex ==-1)return true;
return false;

}

public boolean isFull() {
if( rearIndex +1 == CAPACITY)return true;
return false;
}

public int size() {
return rearIndex +1;
}
}