APCS – Unit 2 – Lab 2.2 – Part 2 – HelloWorld in Eclipse

According to Wikipedia, Eclipse is an integrated development environment (IDE) used in computer programming. It contains a base workspace and an extensible plug-in system for customizing the environment.

Eclipse is written mostly in Java and its primary use is for developing Java applications, but it may also be used to develop applications in other programming languages via plug-ins, including  C, C++, C#,  JavaScript,Perl, PHP,Python, R, Ruby, Rust, Scala, and Scheme. It can also be used to develop documents with LaTeX (via a TeXlipse plug-in) and packages for the software Mathematica.

In this lab, we will learn how to:

  • create a new Java project in Eclipse for Java Developer
  • create a new Java class
  • enter and edit Java source code for a simple program
  • save, compile and debug
  • run the Java program and look for result in the console

Step 1. Start Eclipse.

Double click on the Eclipse IDE for Java Developers icon on your desktop to open Eclipse.

Step 2. Create a new Java Project.

  • File->New->Java Project.

  • Enter a project name into the Project name field, for example, “HelloWorld“.
  • The file will be saved to the default location. If you want to save it somewhere else, you can edit and change the Location.
  • If you have multiple versions of JDK, choose JavaSE-1.8 Java 8.

  • Click “Finish“.

Step 3. Create a new Java class.

  • Right click on “src” -> New -> Class

  • Enter “HelloWorld” into the Name field.
  • A package in Java is used to group related classes. Think of it as a folder in a file directory. You can enter your name as the Package.
  • We want to make this class as a public class (we will explain the concept of modifiers in the next unit)

  • Click the checkbox indicating that you would like Eclipse to create a “public static void main(String[] args)” method.
  • Click “Finish“.

Step 4. Use the Editor to enter and edit the HelloWorld.java source code.

  • A Java editor for HelloWorld.java will open. In the main method enter the following line.
         System.out.println("Hello World");

Step 5. Save and compile the program.

  • Save using ctrl-s. This automatically compiles HelloWorld.java.
  • Or you can click File -> Save.  Again, saving a file in Eclipse automatically triggers the compiler.

Step 6. Run the program.

  • Click on the HelloWorld project to highlight the project, and then click the “Run” button in the toolbar.

Your program prints “Hello, World!” in the Console window on the bottom of the screen.

List of sources and references:
  • https://www.cis.upenn.edu/~matuszek/cit591-2004/Pages/starting-eclipse.html
  • Wikipedila
  • Eclipse.org documentation