Java Level 1 Test

A swimming instructor doesn't move a child to the deep end because they have attended ten lessons. They ask the child to swim one length on their own, and then they decide. This test is your length of the pool for the first level of the course. It covers how Java runs, data types, operators, decisions, loops, arrays and methods. If you pass it, you are ready for objects and classes. If you don't, each answer tells you exactly which lesson to read again.

How the Test Works

• What's in it: 20 multiple-choice questions, then 3 output puzzles where you work out what a short program prints.
• Time: 30 minutes, without notes, an IDE or JShell. Answer on paper first; run code only to check afterwards.
• Pass mark: 16 out of 23. The quiz marks the 20 questions for you. Mark the puzzles yourself, one point each, and add them to your quiz score.
• What it covers: the lessons from "What Is Java" to "Recursion in Java".

Part 1: 20 Questions

Part 2: Output Puzzles

Work out what each program prints, on paper, before you open the solution. The solution shows the full program, its real output and a Try it button. Give yourself one point for each puzzle you get exactly right.

Puzzle 1: Postfix Twice

What is printed?

int i = 10;
i = i++ + i--;
System.out.println(i);

public class PostfixPuzzle {
    public static void main(String[] args) {
        int i = 10;
        i = i++ + i--;
        System.out.println(i);
    }
}

21

Puzzle 2: Continue and Break

What is printed?

for (int i = 0; i < 5; i++) {
    if (i == 3) continue;
    if (i == 4) break;
    System.out.print(i);
}

public class LoopPuzzle {
    public static void main(String[] args) {
        for (int i = 0; i < 5; i++) {
            if (i == 3) continue;
            if (i == 4) break;
            System.out.print(i);
        }
        System.out.println();
    }
}

012

Puzzle 3: Changing an Array in a Method

What is printed?

public static void main(String[] args) {
    int[] a = {1, 2, 3};
    change(a);
    System.out.println(a[0]);
}
 
static void change(int[] arr) {
    arr[0] = 99;
    arr = new int[] {7, 7, 7};
}

public class ArrayPuzzle {
    public static void main(String[] args) {
        int[] a = {1, 2, 3};
        change(a);
        System.out.println(a[0]);
    }
 
    static void change(int[] arr) {
        arr[0] = 99;
        arr = new int[] {7, 7, 7};
    }
}

99

What Your Score Means