Question

class Car{
private String make;

public Car(String make){
this.make = make;
}

public String toString(){
return make;
}
}

class Node<T>{

public T data;
public Node next;

public Node(T data){
this.data = data;
this.next = null;
}

}

public class StackLinkedList<T>{

//Single field of type Node   
//to represent the front of the stack

//operation push()
/*
The push operation is equivalent to the inserting a node at
the head of the list.

*/
public void push(T data){

}


//operation pop()
/*
Pop is equivalent to deleting the node at the front
*/
public int pop() throws Exception{
if(head == null){
System.err.println("Stack is empty");
throw new Exception("Stack is empty");
}

int returnValue = head.data;
head = head.next;
return returnValue;

}

//operation peek()
/*
Peek is equivalent to the pop operation
but instead of removing the node, simply return the data
*/
  
public int peek(){
if(head == null){
System.err.println("Stack is empty");
throw new Exception("Stack is empty");
}
return head.data;
}

//operation print()
/*
Walk through the list (stack) and print it out.
*/

public void print(){
Node temp = head;
while(temp != null){
System.out.print(temp.data + "->");
temp = temp.next;
}
}

//main()
public static void main(String[] args){
/*
Test cases have been set up to test the program. The stack will be
populated with different types.
You can comment them out when while implementing the operations.
*/
  
StackLinkedList s1 = new StackLinkedList();
s1.push(new Car("Honda"));
s1.push(new Car("BMW"));
s1.print();
  
System.out.println("top of the stack: "+ s1.peek());
  
s1.pop();
s1.print();
  
s1.push(new Car("Mercedes"));
s1.print();
  
s1.pop();
s1.pop();
s1.pop();
System.out.println("\n--------------------------------\n");
  
  
StackLinkedList s2 = new StackLinkedList();
s2.push(10);
s2.push(20);
s2.print();
  
System.out.println("top of the stack: "+ s2.peek());
  
s2.pop();
s2.print();
  
s2.push(30);
s2.print();
  
s2.pop();
s2.pop();
s2.pop();
System.out.println("\n--------------------------------\n");

StackLinkedList s3 = new StackLinkedList();
s3.push("cat");
s3.push("dog");
s3.print();
  
System.out.println("top of the stack: "+ s3.peek());
  
s3.pop();
s3.print();
  
s3.push("tiger");
s3.print();
  
s3.pop();
s3.pop();
s3.pop();
}

}

Answer 1

class Car {

private String make;

public Car(String make) {

this.make = make;

}

public String toString() {

return make;

}

}

================================================================

class Node<T> {

public T data;

public Node next;

public Node(T data) {

this.data = data;

this.next = null;

}

}

==============================================================================

public class StackLinkedList<T> {

//Single field of type Node

//to represent the front of the stack

Node<T> head;

//operation push()

/*

* The push operation is equivalent to the inserting a node at the head of the

* list.

*

*/

public void push(T data) {

if(head == null)

head = new Node(data);

else {

Node k = new Node(data);

k.next = head;

head = k;

}

}

//operation pop()

/*

* Pop is equivalent to deleting the node at the front

*/

public T pop() throws Exception {

if (head == null) {

// System.err.println("Stack is empty");

// //throw new Exception("Stack is empty");

return null;

}

T returnValue = head.data;

head = head.next;

return returnValue;

}

//operation peek()

/*

* Peek is equivalent to the pop operation but instead of removing the node,

* simply return the data

*/

public T peek() throws Exception {

if (head == null) {

System.err.println("Stack is empty");

throw new Exception("Stack is empty");

}

return head.data;

}

//operation print()

/*

* Walk through the list (stack) and print it out.

*/

public void print() {

Node temp = head;

while (temp != null) {

System.out.print(temp.data + "->");

temp = temp.next;

}

}

//main()

public static void main(String[] args) throws Exception {

/*

* Test cases have been set up to test the program. The stack will be populated

* with different types. You can comment them out when while implementing the

* operations.

*/

StackLinkedList s1 = new StackLinkedList();

s1.push(new Car("Honda"));

s1.push(new Car("BMW"));

s1.print();

System.out.println("top of the stack: " + s1.peek());

s1.pop();

s1.print();

s1.push(new Car("Mercedes"));

s1.print();

s1.pop();

s1.pop();

s1.pop();

System.out.println("\n--------------------------------\n");

StackLinkedList s2 = new StackLinkedList();

s2.push(10);

s2.push(20);

s2.print();

System.out.println("top of the stack: " + s2.peek());

s2.pop();

s2.print();

s2.push(30);

s2.print();

s2.pop();

s2.pop();

s2.pop();

System.out.println("\n--------------------------------\n");

StackLinkedList s3 = new StackLinkedList();

s3.push("cat");

s3.push("dog");

s3.print();

System.out.println("top of the stack: " + s3.peek());

s3.pop();

s3.print();

s3.push("tiger");

s3.print();

s3.pop();

s3.pop();

s3.pop();

}

}

==================================================================
SEE OUTPUT

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