Define an abstract data type that represents a queue using Java class syntax:

Abstract data type is used to store the data in a structure and provides different method to manipulate the data stored.

// The interface is created using the following method

interface queueADT

{

// Declare a method insert()

public void insert(int data);

// Declare a method delete()

public void delete();

// Declare a method getfront()

public int getfront ();

// Declare a method isempty()

public Boolean isempty()

}

// Interface is implemented by defining the class namelist

class queue implements queueADT

{

// Declare an array list

private int[] list;

// Declare a variable front

private int front;

// Declare a variable rear

private int rear;

// Declare a variable size

private int size;

// Definition of constructor

public queue()

{

// Initialize size is equal to 0

size = 0;

// Initialize rear is equal to 0

rear = 0;

// Initialize front is equal to 0

front = 0;

}

// Definition of insert() method

public void insert(int data)

{

// Assingn value to the list

list[rear]=data;

// Increment the rear

rear++;

// Increment the size

size++;

}

// Definition of delete() method

public void delete()

{

// Check the the value is empty

if(isempty())

{

// Return

return;

}

// Otherwise add the values to the list

for(int i=front; i<rear-1; i++)

{

// Assign the value to the list

list[i] = list [i+1]

}

// Decrement rear

rear--;

// Decrement size

size--;

}

// Definition of getfront() method

public int getfront()

{

// Check the value is empty

if(isempty())

{

// Return

return-1;

}

// Return the front value

return list[front]

}

// Definition of isempty() method

public Boolean isempty()

{

// Check size is equal to 0

if(size==0)

// Return true

return true;

// Otherwise

else

// Return false

return false;

}

// Definition of display() method

public void display()

{

// For loop to print the list using queue

for(int i=front;i<rear;i++)

{

// Print the list

System...