How to Open Source Code in Eclipse

Any developer who is new to Eclipse as an IDE will want to start off right by learning how to open source code in Eclipse. This guide is meant to show you how to easily set up your new IDE so that you can start on your coding without issues. We’ll cover how to open a project and how to get Java development tools installed, including which plug-ins to acquire for building applications, running tests, and more!

Is it possible to have open source code in Eclipse? Or is Eclipse a proprietary program?This tutorial will use GitHUb and GitHub as examples for explaining how to open source code in Eclipse. The benefits of open source are frequently becoming hot topics. Because the overhead is so great and the costs so high, many companies have been forced to make significant changes to their projects and operations.

Open Engineering

Open source software engineering is the practice of creating open source software using an open process. An open process facilitates some degree of open collaboration between developers representing a diversity of thought and motivation. That is, in open source software engineering, the source code of the software that is made publicly available under an open source license is developed in a forge that is also publicly accessible, using processes that actively engage and solicit participation by a community.

Many, perhaps most, open source projects describe themselves as “agile” by some definition of the term. That may mean that they work according to the Agile Manifesto1 or employ some formal or informal agile development methodology. However it is defined, agile development isn’t specific to open source; indeed, agile development methodologies can be employed in a fully private software development context. So, while “agile” is certainly a common characteristic of many open source projects, it isn’t a defining one.

When speaking of open source software engineering, the notion of community frequently comes up. This nebulous term community is generally understood to mean the individuals and organizations that form around an open source project. The community is the users and organizations that adopt open source software and incorporate it into their own projects or products. The community is the primary source of contribution to an open source project, including both the developers who contribute patches and other content to the project and the project team themselves.

Open source software engineering is largely defined by engagement with the community. The degree to which an open source project team engages with a community varies according to the goals of the project.

In Eclipse, when you press Ctrl button and click on any Class names, the IDE will take you to the source file for that class. This is the normal behavior for the classes you have in your project.

But, in case you want the same behavior for Java’s core classes too, you can have it by attaching the Java source with the Eclipse IDE. Once you attach the source, thereafter when you Ctrl+Click any Java class names (String for example), Eclipse will open the source code of that class.

To attach the Java source code with Eclipse,

  1. When you install the JDK, you must have selected the option to install the Java source files too. This will copy the file in the installation directory.
  2. In Eclipse, go to Window -> Preferences -> Java -> Installed JREs -> Add and choose the JDK you have in your system.
  3. Eclipse will now list the JARs found in the dialog box. There, select the rt.jar and choose Source Attachment. By default, this will be pointing to the correct If not, choose the file which you have in your java installation directory.
  4. Similarly, if you have the javadoc downloaded in your machine, you can configure that too in this dialog box.


Transparency is the practice of showing the community what the team is doing. The general idea is to give anybody who cares to pay attention to the project the opportunity to understand the project team’s work.

The act of making source code publicly available under the terms of a recognized open source license certainly meets the definition of transparency. However, making the decision-making processes behind the development of that software publicly available meets the definition even more. Exposing the decision-making process adds predictability for the community, which makes it easier for adopters to set their own development timelines and for the project team to build user excitement for their releases.

Open source projects use a variety of means of open communication to give their community of users and adopters an opportunity to monitor their decision-making process. It’s common for open source project teams to host calls and then capture the minutes from their discussion in one of their public channels. With the emergence of open source foundations and foundries-as-a-service, expectations for transparency have evolved to include publicly accessible issue trackers. However, the true measure of transparency is the degree to which these public-facing tools are used to accurately disclose the decision-making processes of the project.

By default, EclipseSW doesn’t use the JDKW JRE. So, let’s say you have a JavaSW class such as the following Test class.

Test class

If you click on ‘String’ and click F3, Eclipse will try to jump to the String class. However, since no source code is attached to the JRE, we see the following:

Source not found

So, let’s switch our Eclipse to use the JDK JRE. Go to Window → Preferences → Java → Installed JREs. This will list the JREs that Eclipse knows about. If the JDK JRE isn’t there, click on the Search… button, which brings up the Directory Selection window, where you can select your JDK directory. Click OK to perform the search for the JRE in the JDK directory.

Finding JDK JRE

Eclipse should find the JRE within your JDK directory, as in the example below. Check the JDK JRE checkbox and click OK.

Selecting JDK JRE


Openness is the practice of letting others participate. That is, “open” in this context means “open to all comers.” Like all practices in open source, there is a range or degree of openness.

Perhaps the most important thing that an open source project can do to make it possible for members of its community to participate is to use the same source code repository as the community. When developers push their content directly (and frequently) into a repository that the rest of the community has access to, so that the entire community has access to the most up-to-date version of the project content, members of that community have the ability to keep up with project development and an equal opportunity to contribute. Put another way, when a project team works in private and then periodically synchronizes its internal repository with a public one, it is basically impossible for anybody outside of the private team to contribute any content.

Making an open source project’s repositories publicly available and accessible does not necessarily mean that everybody has equal privileges. In an open-collaboration scenario, it is possible for members of the community to earn additional privileges by demonstrating knowledge of the open source project’s code base and development practices. For example, community members may make contributions to an open source project, but those contributions need to be received, reviewed, and accepted by a member of the project’s development team. Over time, a contributor who has demonstrated knowledge of the project’s code base and an understanding of the project’s rules of engagement would be invited to join the project team.

Likewise, an issue tracker that is publicly available and accessible to the community makes it possible for the entire community to participate on equal footing. Open-issue tracking lets the community raise issues, provide direct feedback, and participate in planning. In essence, keeping source repositories, issue trackers, and communication channels open for community participation makes the project team a part of the community and not separate from it.


This book is written for a novice audience. It assumes that you have no prior knowledge of open source development, and walks you through the best open-source development environment on the market, Eclipse by far to begin writing software that you can produce and share with others.


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