Note: There is nothing to turn in for this lab. The lab’s primary goal is to ensure that you’ve practiced a bit with Maven and (potentially) experienced some of the complexities.
Note: This lab is all new for Fall 2024. There may be unexpected problems.
a. Make sure that you’ve completed a reasonable amount of the Getting started with Java lab. In particular, you should have,
edu.grinnell.csc207.util, edu.grinnell.csc207.main, and edu.grinnell.csc207.experiments.HelloWorld class in the main package.FizzBuzz class in the util package.ArrayUtils class in the util package.FizzBuzzOne class in the main package.MinExperiments class in the experiments package.All of these files should compile successfully.
b. Make sure that you have the reading on Maven available to you.
Driver: A
As you’ve learned, when we create a new Maven project, we have to do some configuration. Let’s start there.
a. Set up a new project using the instructions. Make sure to use edu.grinnell.csc207 as the groupId and maven-sample as the artifactID.
b. In edu.grinnell.csc207, you should have a file called App.java. Take a quick look at the file to make sure you understand what it should do.
c. Compile the project with mvn compile or mvn compile -q.
d. When we compiled using javac, we found that the compiled files ended up in the same directory as the .java files, which may not be ideal. Determine where the .class files end up in Maven.
e. Once you know where the .class files end up, run the compiled App.java.
f. Make a change to the output in App.java, recompile, and re-run to make sure that the change has taken effect.
g. Determine the results of running mvn clean or mvn clean -q.
h. Update your pom.xml to use Java 17.
Driver: B
We have directories set up, but no files. Fortunately, we’ve started a project, so we’ll move them over.
a. App.java is a placeholder. Get rid of it.
b. Get rid of src/test/java/edu/grinnell/csc207/AppTest.java.
c. Set up directories for your three Java packages. This will entail making subdirectories of src/main/java/edu/grinnell/csc207/.
d. Copy the .java files from your previous lab over to this project.
e. Ensure that you can compile all the files with mvn compile or
mvn compile -q.
f. Make sure that you can run at least one of the main classes. (Warning: The top level of the Maven project is not the top level of the Java package hierarchy; you may need to change your location.)
Driver: A
The normal outcome of a Maven project is a .jar file that contains the code and other useful stuff.
a. Create the .jar file for this project using mvn package or mvn package -q.
b. Find the jarfile.
c. Run one of the main files with java -cp JARFILE edu.grinnell.csc207.main.HelloWorld (or something similar).
d. Determine what’s in the .jar file with jar tf JARFILE. Most important is that it includes the .class files in the appropriate location.
Driver: B
Ideally, if a project is intended to be executed, it has a designated main class that should be run.
a. Add the appropriate code to your pom.xml file to ensure that your FizzBuzzOne class is used as the default class to run. You will need to check the reading for the particular XML to use.
b. Rebuild your .jar file.
c. Try executing your .jar file with java -jar JARFILE to ensure that you get FizzBuzz to run..
Driver: A
We should not be able to build the .jar file if there are syntax or other errors in our programs.
a. Make a change to one of your .java files that is likely to cause problems. For example, remove a semicolon.
b. Try to rebuild the .jar file and determine what happens.
c. Repair the error(s) you introduced.
Driver: B
Ideally, we will test our code regularly. Since you don’t yet know how to write unit tests, we’re providing some for you.
a. Update the pom.xml file to use JUnit 5. The reading contains instructions how.
b. Run mvn test or mvn test -q to see what happens.
c. Create the directory src/test/java/edu/grinnell/csc207/util
mkdir -p src/test/java/edu/grinnell/csc207/util
d. Add the file ArrayMinTests.java with the following contents.
package edu.grinnell.csc207.util;
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
/**
* Tests of the ArrayUtils.min method.
*/
public class ArrayMinTests {
/**
* An array with one value.
*/
@Test
public void oneValueTest() {
assertEquals(0, ArrayUtils.min(new int[] { 0 }), "Just zero");
} // oneValueTest()
/**
* Smallest at the front.
*/
@Test
public void smallestFirstTest() {
assertEquals(1, ArrayUtils.min(new int[] { 1, 2, 3 }), "Smallest first");
} // smallestFirstTest()
/**
* Smallest at the end
*/
@Test
public void smallestLastTest() {
assertEquals(2, ArrayUtils.min(new int[] { 7, 4, 3, 8, 2 }),
"Smallest last");
} // smallestLastTest()
} // class ArrayMinTests
e. Run mvn test or mvn test -q to see what happens.
f. Update ArrayUtils.min to return always return 0 rather than the smallest value.
g. Run mvn test or mvn test -q to see what happens.
h. Restore the min method.
Driver: A
Finally, we turn to style. Almost anywhere you end up working, you’ll find that there’s a “house style” that you should follow. Maven (well, the checkstyle tool that Maven can incorporate) helps you identify stylistic problems. And, unlike failed tests, failed style issues won’t stop you from packaging your project. (They will, however, prevent you from getting an M or an E.)
a. Add the checkstyle plugin information from the reading to your pom.xml file.
b. Download csc-207-checks.xml and put it at the top level of your project (that is, in the same directory as your pom.xml file).
c. Run mvn checkstyle:check or mvn checkstyle:check -q to check your style.
d. Fix your stylistic errors. Ask the course staff if you don’t understand them.
Although there’s nothing to turn in for this lab, you should make sure that both partners have access to all the files. One easy way to do so is to zip everything up and send the .zip file to your partner.