Challenges

Remember the rules for this are

• Try to use only the information given up to this point in this book.
• Try not to give up until you've given it a solid attempt

Challenge 1

Make a method named parseIntChecked that works the same as Integer.parseInt but throws a checked exception instead of an unchecked one.

// CODE HERE

void main() throws Exception {
    int x = parseIntChecked("45");
    IO.println(x);

    parseIntChecked("abc");
}

Challenge 2

The following program will not compile. Make it compile by propagating the checked exception thrown by the doesSomethingDangerous method.

int doesSomethingDangerous(int value) {
    if (value == 1) {
        throw new Exception("1 does not work");
    }
    return 3 * value + 2;
}

int compute(int start) {
    return square(doesSomethingDangerous(start));
}

int square(int x) {
    return x * x;
}

void main() {
    int x = Integer.parseInt(IO.readln("Give a starting number: "));
    IO.println(compute(x));
}

Challenge 3

The following program is the same as the last one. Instead of propagating the exception, make it so that compute catches and rethrows the checked exception as an unchecked one.

int doesSomethingDangerous(int value) throws Exception {
    if (value == 1) {
        throw new Exception("1 does not work");
    }
    return 3 * value + 2;
}

int compute(int start) {
    return square(doesSomethingDangerous(start));
}

int square(int x) {
    return x * x;
}

void main() {
    int x = Integer.parseInt(IO.readln("Give a starting number: "));
    IO.println(compute(x));
}