Unit 7 ArrayList P3

• ArrayList Coding Activity
  • Objective:
  • Activity Outline:

ArrayList Coding Activity

Objective:

Students will create, manipulate, and sort an ArrayList of integers.

Activity Outline:

1. Create an ArrayList:
   • Task: Create an ArrayList of integers and add 5 elements of your choice.
   • Hint: Use the ArrayList class and the .add() method to add elements.
2. Modify an Element:
   • Task: Change the second element (index 1) of the ArrayList to a new value (e.g., 100).
   • Hint: The .set() method allows you to update an element at a specific index.
3. Remove an Element:
   • Task: Remove the third element (index 2) from the ArrayList.
   • Hint: Use the .remove() method to delete an element by its index.
4. Search for an Element:
   • Task: Check if a specific number (e.g., 30) is in the ArrayList and print a message based on whether it is found or not.
   • Hint: The .contains() method can be used to check for the presence of an element.
5. Loop Through the ArrayList:
   • Task: Use a for loop to print each element of the ArrayList.
   • Hint: You can use a traditional for loop or an enhanced for loop (for-each) to iterate through the elements.
6. Sort the ArrayList:
   • Task: Sort the ArrayList in ascending order.
   • Hint: Use Collections.sort() to sort the ArrayList.
7. Print the Sorted ArrayList:
   • Task: Print the sorted ArrayList to see the updated order of the elements.
   • Hint: Use System.out.println() to print the sorted list.

import java.util.ArrayList;
ArrayList<Integer> myIntegerList = new ArrayList<Integer>();
System.out.println("Original ArrayList: " + myIntegerList);
myIntegerList.add(35);
myIntegerList.add(53);
myIntegerList.add(78);
myIntegerList.add(24);
myIntegerList.add(18);
System.out.println("ArrayList with new elements freshly added: " + myIntegerList);

Original ArrayList: []
ArrayList with new elements freshly added: [35, 53, 78, 24, 18]

System.out.println("Third element before change: " + myIntegerList.get(2));
myIntegerList.set(2, 59);
System.out.println("Third element after change: " + myIntegerList.get(2));

Third element before change: 78
Third element after change: 59

System.out.println("ArrayList before removing second element: " + myIntegerList);
myIntegerList.remove(1); //removes second element which is 53, from the ArrayList
System.out.println("ArrayList after removing second element: " + myIntegerList);

ArrayList before removing second element: [35, 53, 59, 24, 18]
ArrayList after removing second element: [35, 59, 24, 18]

int searchNumber = 30;
    if (myIntegerList.contains(searchNumber)) {
        System.out.println(searchNumber + " is found in the ArrayList.");
    } else {
        System.out.println(searchNumber + " is not found in the ArrayList.");
    }

int searchNumber = 59;
    if (myIntegerList.contains(searchNumber)) {
        System.out.println(searchNumber + " is found in the ArrayList.");
    } else {
        System.out.println(searchNumber + " is not found in the ArrayList.");
    }

30 is not found in the ArrayList.
59 is found in the ArrayList.

for(int number : myIntegerList) {
    System.out.println(number);
}

35
59
24
18

import java.util.Collections;
Collections.sort(myIntegerList);

System.out.println(myIntegerList);

[18, 24, 35, 59]