Java - Dynamic Stack Assignment
From WLCS
Contents
Objectives
- You will implement a dynamically-sized queue using linked Nodes
- You will implement queue methods (enqueue/add, dequeue/remove, etc.)
- You will test your dynamic queue in a main() method
Resources
Directions
Before & After Visualizations
- Take out a pencil and paper or a dry-erase board and marker
- Load the Dynamic Stack Visualization
- Consider each of the following questions and use the visualization tool to help you answer them. Practice drawing each of the visualizations yourself.
- What does an empty stack look like? (The top reference variable is null)
- For each of the following actions, assess what the picture looks like Before? then After? What changes occurred to make the Before image become the After image?
- push(4)
- push(2)
- pop()
- pop()
Node class
- Create a new class called Node
- Implement the code for the Node class using Media:Node.java as a guide
- You will want to add a specific constructor that takes in data as a parameter, and saves the data into the num attribute
DynamicStack class
- Create a new class called DynamicStack
- Create a default constructor for a DynamicStack
- Implement the following attributes and methods:
Attributes
- What attribute must we keep track of when we talk about stacks? (Hint: rhymes with "mop")
- Create a Node reference for the most important stack attribute
- Do not forget to initialize it to null
Methods
- void push(int data)
- push() should not return anything
- push() creates a new Node with the data parameter
- assign the new Node's next reference to the top (so that the new Node is linked to the current top Node)
- update the top to reference the new Node!
- int pop()
- pop() returns Integer.MIN_VALUE if the stack is empty
- pop() removes the value on top of the stack and returns it
- update the top so that it references its next Node (you need to update top before you return the data)
- int top()
- return the value at the top of the stack
- return Integer.MIN_VALUE if the stack is empty
- boolean isEmpty()
- return true if the stack is empty, and false otherwise
- Hint: What does top reference when the stack is empty?
- String toString()
- Use a loop to generate the String version of your stack's data
- return the String
- void print()
- print your entire stack starting at the top (to null)
- Hint: use the for loop that we covered in class
Testing
- You should be able to reuse your main() method from the static stack assignment
- Write a loop that pushes A LOT of data to test the dynamic size
- Write a loop that pops A LOT of data to make sure it works too