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Trail: Getting Started
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# Answers to Questions and Exercises: Getting Started

## Questions

Question 1: When you compile a program written in the Java programming language, the compiler converts the human-readable source file into platform-independent code that a Java Virtual Machine can understand. What is this platform-independent code called?

Answer 1: Bytecode.

Question 2: Which of the following is not a valid comment:

a. `/** comment */`
b. `/* comment */`
c. `/* comment`
d. `// comment`

Answer 2: c is an invalid comment.

Question 3: What is the first thing you should check if you see the following error at runtime:

    Exception in thread "main" java.lang.NoClassDefFoundError:
    HelloWorldApp.java.

Answer 3: Check your classpath. Your class cannot be found.

Question 4: What is the correct signature of the `main` method?

Answer 4: The correct signature is `public static void main(String[] args)` or `public static void main(String... args)`

Question 5: When declaring the `main` method, which modifier must come first, `public` or `static`?

Answer 5: They can be in either order, but the convention is `public static`.

Question 6: What parameters does the `main` method define?

Answer 6: The `main` method defines a single parameter, usually named `args`, whose type is an array of `String` objects.

## Exercises

Exercise 1: Change the `HelloWorldApp.java` program so that it displays `Hola Mundo!` instead of `Hello World!`.

Answer 1: This is the only line of code that must change:

    System.out.println("Hola Mundo!"); //Display the string.

Exercise 2: You can find a slightly modified version of `HelloWorldApp` here: `HelloWorldApp2.java`

The program has an error. Fix the error so that the program successfully compiles and runs. What was the error?

Answer 2: Here's the error you get when you try to compile the program:

    HelloWorldApp2.java:7: unclosed string literal
            System.out.println("Hello World!); //Display the string.
                               ^
    HelloWorldApp2.java:7: ')' expected
            System.out.println("Hello World!); //Display the string.
                                                                    ^
    2 errors

To fix this mistake, you need to close the quotation marks around the string. Here is the correct line of code:

     System.out.println("Hello World!"); //Display the string.

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