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.

Write a method named isUpperCase which tells you if a given String is already made of all upper-case characters.

Hint: One way to do this is to call .toUpperCase and check if the result is the same as the input you were given.

boolean isUpperCase(String s) {
    // -----------
    // CODE HERE
    // -----------
}

void main() {
    // true
    System.out.println(isUpperCase("ABC"));
    // false
    System.out.println(isUpperCase("abc"));
    // false
    System.out.println(isUpperCase("AbC"));
}

Challenge 2.

Do the same as above, but check if a given String is made of all lower case letters.

boolean isLowerCase(String s) {
    // -----------
    // CODE HERE
    // -----------
}

void main() {
    // false
    System.out.println(isLowerCase("ABC"));
    // true
    System.out.println(isLowerCase("abc"));
    // false
    System.out.println(isLowerCase("AbC"));
}

Challenge 3.

Add an instance method named scream to the Muppet class. This should replace the name of the muppet with the name in upper case letters + an exclamation point (!) at the end.

class Muppet {
    String name;

    // -------------
    // CODE HERE
    // -------------
}

void main() {
    var kermit = new Muppet();
    kermit.name = "kermit";

    // kermit
    System.out.println(kermit.name);

    // KERMIT!
    kermit.scream();
    System.out.println(kermit.name);
}

Challenge 4.

Write a method called echo.

If echo is given a non-blank String, it should print You Said: <...> where <...> is the String they gave minus any leading or trailing whitespace.

If echo is given a blank String, it should print You Didn't Say Anything.

void echo(String s) {
    // -------------
    // CODE HERE
    // -------------
}

void main() {
    // You Said: Hello
    echo("Hello");

    // You Said: Hello
    echo("        Hello         ");

    // You Didn't Say Anything
    echo("");

    // You Didn't Say Anything
    echo("                ");
}