void main() {
    String name = IO.readln("Your name (or press Enter to skip): ").strip();

    if (name) {
        IO.println("Hello, " + name + ".");
    } else {
        IO.println("Hello, stranger.");
    }
}

// From Groundwork, chapter 4 (ch04-making-decisions), box 9.
// This example is from Groundwork, licensed CC BY-NC-SA 4.0.
// Run with: java ch04_09.java
// This fails on purpose: it does not compile—A String used as a condition, which javac refuses. The error message is the lesson.