Practice Exercises

Hands-on Java exercises

Two practice exercises for Java lecture with TODO starters and hidden solutions.

Auteur

Affiliations

Emmanuel BRUNO

Université de Toulon

LIS UMR CNRS 7020

Java Practice Exercises

Related lecture: 02_demo_L_java.qmd

This notebook contains interactive exercises. Edit the code cells and run them to check your solutions.

Exercise 1 — Control Flow

Task: Complete the function checkAge(int age) that returns "Majeur" if age >= 18, otherwise "Mineur".

Then test it with ages 15, 18, and 25.

// Write your checkAge function here
String checkAge(int age) {
    // TODO: implement this
    return "";
}

// Test cases
System.out.println("Age 15: " + checkAge(15));
System.out.println("Age 18: " + checkAge(18));
System.out.println("Age 25: " + checkAge(25));

Age 15: 
Age 18: 
Age 25: 

Expected output:

Age 15: Mineur
Age 18: Majeur
Age 25: Majeur

---

Exercise 2 — Arrays & Methods

Task: Write a method sumArray(int[] arr) that returns the sum of all elements in the array.

Test it with the array {10, 20, 30, 40, 50}.

// Write your sumArray function here
int sumArray(int[] arr) {
    // TODO: implement this
    return 0;
}

// Test case
int[] numbers = {10, 20, 30, 40, 50};
System.out.println("Sum: " + sumArray(numbers));

Sum: 0

Expected output:

Sum: 150

---

Solutions

Run the cells below to see the solutions (after attempting the exercises yourself!).

Solution 1 — Control Flow

String checkAge(int age) {
    if (age >= 18) {
        return "Majeur";
    } else {
        return "Mineur";
    }
}

// Test cases
System.out.println("Age 15: " + checkAge(15));
System.out.println("Age 18: " + checkAge(18));
System.out.println("Age 25: " + checkAge(25));

Age 15: Mineur
Age 18: Majeur
Age 25: Majeur

Solution 2 — Arrays & Methods

int sumArray(int[] arr) {
    int sum = 0;
    for (int value : arr) {
        sum += value;
    }
    return sum;
}

// Test case
int[] numbers = {10, 20, 30, 40, 50};
System.out.println("Sum: " + sumArray(numbers));

Sum: 150