AP Computer Science A Unit 7 Review

AP Computer Science A Unit 7 Review with example codes….

1. Introduction to ArrayList

import java.util.ArrayList;

public class ArrayListIntroductionExample {
    public static void main(String[] args) {
        // Creating an ArrayList of integers
        ArrayList<Integer> numbers = new ArrayList<>();
        
        // Adding elements to the ArrayList
        numbers.add(10);
        numbers.add(20);
        numbers.add(30);
        numbers.add(40);
        numbers.add(50);
        
        // Displaying the ArrayList
        System.out.println("ArrayList: " + numbers);
    }
}

2. ArrayList Methods

import java.util.ArrayList;

public class ArrayListMethodsExample {
    public static void main(String[] args) {
        ArrayList<String> fruits = new ArrayList<>();
        
        // Adding elements to the ArrayList
        fruits.add("Apple");
        fruits.add("Banana");
        fruits.add("Orange");
        
        // Getting the size of the ArrayList
        System.out.println("Size: " + fruits.size()); // Output: 3
        
        // Accessing elements using indices
        System.out.println("First element: " + fruits.get(0)); // Output: Apple
        
        // Removing an element by index
        fruits.remove(1); // Remove Banana
        
        // Checking if an element is in the ArrayList
        System.out.println("Contains Orange: " + fruits.contains("Orange")); // Output: true
        
        // Displaying the updated ArrayList
        System.out.println("Updated ArrayList: " + fruits);
    }
}

3. Traversing ArrayLists

import java.util.ArrayList;

public class ArrayListTraversingExample {
    public static void main(String[] args) {
        ArrayList<String> fruits = new ArrayList<>();
        fruits.add("Apple");
        fruits.add("Banana");
        fruits.add("Orange");
        
        // Traditional for loop to traverse the ArrayList
        System.out.println("Using traditional for loop:");
        for (int i = 0; i < fruits.size(); i++) {
            System.out.println("Element at index " + i + ": " + fruits.get(i));
        }
        
        // Enhanced for loop (for-each) to traverse the ArrayList
        System.out.println("\nUsing enhanced for loop:");
        for (String fruit : fruits) {
            System.out.println("Element: " + fruit);
        }
    }
}

4. Developing Algorithms Using ArrayLists

import java.util.ArrayList;

public class ArrayListAlgorithmsExample {
    public static void main(String[] args) {
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(15);
        numbers.add(3);
        numbers.add(8);
        numbers.add(23);
        numbers.add(7);
        numbers.add(12);
        
        // Finding the maximum value in the ArrayList
        int max = numbers.get(0);
        for (int i = 1; i < numbers.size(); i++) {
            if (numbers.get(i) > max) {
                max = numbers.get(i);
            }
        }
        System.out.println("Maximum value in the ArrayList: " + max);
        
        // Finding the minimum value in the ArrayList
        int min = numbers.get(0);
        for (int i = 1; i < numbers.size(); i++) {
            if (numbers.get(i) < min) {
                min = numbers.get(i);
            }
        }
        System.out.println("Minimum value in the ArrayList: " + min);
        
        // Calculating the sum of the ArrayList elements
        int sum = 0;
        for (int number : numbers) {
            sum += number;
        }
        System.out.println("Sum of ArrayList elements: " + sum);
    }
}

5. Searching

import java.util.ArrayList;

public class ArrayListSearchingExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Alice");
        names.add("Bob");
        names.add("Charlie");
        
        // Checking if an element is in the ArrayList
        boolean containsAlice = names.contains("Alice");
        System.out.println("Contains Alice: " + containsAlice); // Output: true
        
        boolean containsEve = names.contains("Eve");
        System.out.println("Contains Eve: " + containsEve); // Output: false
    }
}

6. Sorting

import java.util.ArrayList;
import java.util.Collections;

public class ArrayListSortingExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Charlie");
        names.add("Alice");
        names.add("Bob");
        
        // Sorting the ArrayList
        Collections.sort(names);
        
        // Displaying the sorted ArrayList
        System.out.println("Sorted ArrayList: " + names);
    }
}