CS1331 Programming Exercise 0 Solution

Authors: Vince, Jack, Andrew
Purpose
Hello and welcome to your first CS1331 programming assignment! This assignment is just to verify you have Java installed properly on your machine and you are able to run a Java program.
Solution Description
Installing Java
In this class, we will be using Java 11 (openjdk). Make sure you have this version installed, even if you already have a previous version of Java. We have detailed instructions for this on the course canvas page in “Guide to Installing Java.pdf”.
After running javac -version , you should see this output:

javac 11.0.9.1

After running java -version , you should see this output:

OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.9.1+1)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.9.1+1, mixed mode)
Take and save a screenshot of your terminal showing the result of java –version

Writing and Compiling a Java Class
In order to create a Java class, you must first create a file with the .java extension. In our example here, we will use Test.java. Within the class, you will need to write a class header. For now, just memorize that you need to write public class before your class name. We will go more in depth about what exactly this means later. As for the class name, it must exactly match the name of the file.
Therefore, our example should have the following (note the capitalization):
public class Test {
}
Now that you have written a Java class, you should be able to compile your code! Navigate to the directory where you have saved this file in the command line.
After navigating to the proper directory, you will be able to compile the Java class you've just created! You do this by using the command javac FileName.java. Since we named our Java example file Test.java, we compile it using javac Test.java.
This should create a new file in your directory called Test.class! Created by the Java compiler, this file will contain Java bytecode, and it will not make much sense to you if you open it up. However, it makes a lot of sense to the Java Virtual Machine, or the JVM (a computing machine that allows our program to run).
If a new file was not created, your program did not compile. Read the compilation error produced in your command prompt and fix it before proceeding!

The Main Method
Remember, the method signature should look like this:
public static void main(String[] args) {
}
This method is critical for a Java class to be "runnable." Now, you can write the contents of your first Java program within your main method. For this assignment simply do the following:
• Print out “Hello World”
To run your program, use the command java FileName. Since we named our file Test.java, we will use the command java Test. Note that we didn't include the .class extension after Test; it won't run if you do java Test.class. If you ever want to run a new version of your program after making alterations, know that you must recompile before doing so.
Good luck, and happy hacking!
Turn-In Procedure
Submission
To submit, upload the files listed below to the corresponding assignment on Gradescope:
• Test.java
• Screenshot of your terminal showing the result of java –version
Make sure you see the message stating "PE0 submitted successfully". From this point, Gradescope will run an autograder on your submission verifying all necessary files are included and working as intended. Note: the nature of some assignments means they are not fully autogradable and will require some manual grading after submission. Although all autograder tests will be made visible, this is NOT always your final grade.
Collaboration
No collaboration is allowed on this assignment. See syllabus for more details.