Labs

In these labs we will use ArrayList to store and retrieve data, and as the internal storage for a data structure.

  1. Write a program that contains an ArrayList of the names of the students in your class. Use a foreach loop to print out each name. (Do not copy-paste from an example.)

(Solution: Students.java)

  1. Write a program that uses Math.random() to build an ArrayList of 10 numbers between 0 and 1 (exclusive). Use a standard for loop to print out each number to 3 decimal places. (Hint: System.out.printf)

(Solution: Numbers.java)

  1. com.example.generics.drills.Stack

In this lab we will create a data structure called a Stack. This will be a last-in-first-out (LIFO) stack. This means the last element added is the first one removed. (Think of a stack of dishes: one person adds a dish to the stack, the next person takes that dish off the top of stack.)

We can say that we push and item on the stack, and pop an item from the stack.

LIFO stack

The class com.example.generics.drills.Stack uses Objects. We will be changing it to a generic class.

Internally, your Stack<E> will use an ArrayList<E>.

The Stack has four methods. * E push(E item) - add an item to the Stack. Return a reference to the item. * E pop() - remove and return the item at the top of the Stack, or null if the Stack is empty. * E peek() - return the item at the top of the Stack, but do not remove it. Return null if the Stack is empty. * int search(Object o) - search for the item in the Stack by iterating through the list and calling item.equals(o). Return the index of the item, or -1 if it is not in the Stack.

Refer to Generic \<Types> for a reminder on using the type parameter. (You may want to complete the class to hold Object references, then add in <E> and E.)

(Note: There are JUnit tests for the solution in the test/com.example.generics.solutions package. You could copy these into the test/com.example.generics.drills package to test your own class. Be sure the test is using your class, and not the one from the solutions package.)

(Solution: Stack.java, StackTests.java)

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