Creating Your First Java Project in Eclipse

Imagine you have just installed Eclipse and written your first Java program. When you close the program, where does that work go, and how would you find it again next week? Eclipse answers this with a single idea: every piece of work you do in Eclipse is kept inside one place on your computer. Understanding that place, and the way the Eclipse window is arranged around your work, is the foundation for everything you will do in the environment.

This article follows the path a learner takes in three steps. First comes the workspace, the place where work is stored. Second comes the window, which is made of sections holding views. Third come the perspectives, which group those views for different jobs. After that, you will walk through creating a Java project, the container that holds the source files for one program. Read this with a real Eclipse window open so you can check each step as you go.

A workspace is not something Eclipse creates silently in the background. The first time you start Eclipse, it asks you to specify a workspace. You can accept the default name that is offered, or type a name of your own. The choice matters because the workspace is the directory where your work is kept, so the name you pick tells you where to look later.

One installation of Eclipse is not limited to one workspace. You can keep, for example, one workspace for coursework and another for a separate project, then choose between them each time you launch the program. The workspace you select at startup is the one whose contents appear in the environment for that session.

The Eclipse graphical user interface is best understood as one large window that has been divided into several sections. Each section is not empty space waiting to be filled; it holds one or more views. A view is the component that actually shows you something. Read the window from the outside in: the window contains sections, and each section contains views.

The source does not fix which view appears in which section; it only says that each section holds one or more views. What it does specify is the kinds of view you will meet: a text editor, a place where a program can do input and output, and a list of your projects. Because each view has a different job, the window needs several of them at once, and that is why it is divided into sections in the first place.

Views are the individual panels. A perspective is the whole set of views in the window, meaning one arrangement of those panels that suits a particular job. Changing perspective changes which views make up the window, which in turn changes what the window is good for at that moment. The Java Perspective is the default for compiling and running programs. The Debug Perspective helps you find semantic errors, which are errors in what a program means or does rather than in its surface form.

Before you can write a single line of Java in Eclipse, you have to decide where that code will live. Eclipse does not treat a loose source file as a starting point. All of your work is organized inside a container called a project. A project gathers the source files, the library settings, and the other resources a program needs, so the IDE always knows what belongs to which program.

The wizard has two sections beyond the name that need your attention. One controls which Java environment the project runs against, and the other controls whether the project is treated as a modular program. Eclipse remembers the JRE and Module settings from earlier, so you should check them again for each new project rather than trusting the values shown from last time.

After you click Finish, the new project appears in the Package Explorer view on the left side of the Eclipse window. The project is a folder-like entry you can expand by clicking the small triangle or plus sign beside its name. With the default settings, two items matter most: the src directory and the JRE System Library.

The two items play different roles. The src directory is where you write. When you later add a class, it belongs inside src. The JRE System Library is not something you write; it is the collection of standard built-in classes that come with Java, controlled by the JRE setting you chose in the wizard.