The JavaTM Tutorial

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Trail: Getting Started

## 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?

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

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

> Question 3: In The Java Tutorial, what is the URL of the page that describes Khwarazm? (Hint: You can find the answer by going to the home page and clicking on the link to the Search page where you can perform a search.)
> Question 4: Answer the following questions:

> > a. What is the highest version number of the Java 2 SDK, Standard Edition, that is available for download (early-access releases included)? (Hint: You can find the answer at http://java.sun.com/j2se/.)

> > b. What is the highest version number for an SDK that you can download and use in shipping products (that is, not an early-access release)?

> > c. What is the lowest version number for an SDK that you can download? (Note that "SDK" used to be called "JDK.")

> Question 5: Answer the following questions:

> > a. Which bug has the highest number of votes at the Java Developer Connection? Give the bug number, description, and number of votes. (Hint: Look for the answer at http://developer.java.sun.com/developer/bugParade/.)

> > b. Does the bug report give a workaround? If so, what is it?

> Question 6: What is the first thing you should check if the interpreter returns the error: `Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorldApp.java.
> `

### Exercises

> Exercise 1: Change the `HelloWorldApp.java` program so that it displays `Hola Mundo!` instead of `Hello World!`.
> Exercise 2: Download this file: `Useless.java` Compile and run this program. What is the output?

> Exercise 3: 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?

> Exercise 4: Change the height of the `HelloWorld` applet from `25` to `50`. Describe what the modified applet looks like.

> Exercise 5: Download the following two source files:

> - `FirstClass.java`
> - `SecondClass.java`
> Compile the files, and then run the resulting program. What is the output? If you have trouble compiling the files but have successfully compiled before, try unsetting the `CLASSPATH` environment variable, and then compile again.

Check your answers.

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