Practice›Java Fundamentals›Module 4. Classes & Objects›4.1 Objects and fields

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4.1 Objects and fields — safe name

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Task

Fill in safeName so that it returns the dog's name — or the text unknown when it is given null instead of a dog.

The program prints Rex and then unknown. Without the guard the second call would crash with a NullPointerException.

Your solution

class Dog {
    String name;

    Dog(String name) {
        this.name = name;
    }
}

public class Main {

    public static String safeName(Dog d) {
        // return the dog's name, or "unknown" when there is no dog

    }

    public static void main(String[] args) {
        System.out.println(safeName(new Dog("Rex")));
        System.out.println(safeName(null));
    }
}

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