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6.1: Installing DrJava

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    The easiest way to start programming in Java is to use a website that compiles and runs Java code in the browser. Examples include,,, and others.

    If you are unable to install software on your computer (which is often the case in public schools and Internet cafés), you can use these online development environments for almost everything in this book.

    But if you want to compile and run Java programs on your own computer, you will need:

    • The Java Development Kit (JDK), which includes the compiler, the Java Virtual Machine (JVM) that interprets the compiled byte code, and other tools such as Javadoc.
    • A simple text editor such as Notepad++ or Sublime Text, and/or an IDE such as DrJava, Eclipse, jGrasp, or NetBeans.

    The JDK we recommend is Java SE (Standard Edition), which Oracle makes available for free. The IDE we recommend is DrJava, which is an open-source development environment written in Java (see Figure 15.1.1).

    To install the JDK, search the web for “download JDK” which should take you to Oracle’s website. Scroll down to “Java Platform, Standard Edition” and click the download button under JDK. Then accept the license agreement and select the installer for your operating system. Don’t forget to run the installer after you download it!

    To install DrJava, visit and download the JAR file. We recommend that you save it to your Desktop or another convenient location. Simply double-click the JAR file to run DrJava. Refer to the DrJava documentation ( for more details.

    Screenshot of DrJava editing the hello world program.
    Figure \(\PageIndex{1}\): Screenshot of DrJava editing the hello world program.

    When running DrJava for the first time, we recommend you change three settings from the Edit > Preferences menu under Miscellaneous: set the Indent Level to 4, check the Automatically Close Block Comments box, and uncheck the Keep Emacs-style Backup Files box.

    This page titled 6.1: Installing DrJava is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Allen B. Downey (Green Tea Press) .

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