Introduction to Eclipse Overview Eclipse Background Obtaining and Installing Eclipse Creating a Workspaces Projects Creating Classes Compiling and Running Code Debugging Code Sampling of Features Summary What is Eclipse Eclipse started as a proprietary IBM product IBM Visual age for Smalltalk Java Embracing the open source model IBM opened the product up Open Source It is a general purpose open platform that facilitates and encourages the development of third party plug ins Best known as an Integrated Development Environment IDE Provides tools for coding building running and debugging applications Originally designed for Java now supports many other languages Good support for C C Python PHP Ruby etc Prerequisites for Running Eclipse Eclipse is written in Java and will thus need an installed JRE or JDK in which to execute JDK recommended Eclipse on GL This years coordinated release known as Ganymede of the Eclipse IDE for Java Developers has been installed on GL From any of the Linux machines in the labs simply run the command eclipse Obtaining Eclipse Eclipse can be downloaded from http www eclipse org downloads packages Be sure to grab Eclipse IDE for Java Developers Eclipse comes bundled as a zip file Windows or a tarball all other operating systems Some versions of Linux i e Fedora Ubuntu offer Eclipse in their respective repositories and can be downloaded using the appropriate tool i e yum apt get Installing Eclipse Simply unwrap the zip file to some directory where you want to store the executables On windows I typically unwrap the zip file to C eclipse I then typically create a shortcut on my desktop to the eclipse executable C eclipse eclipse exe Under Linux I typically unwrap to opt eclipse Launching Eclipse Once you have the environment setup go ahead and launch eclipse You should see the following splash screen Selecting a Workspace In Eclipse all of your code will live under a workspace A workspace is nothing more than a location where we will store our source code and where Eclipse will write out our preferences Eclipse allows you to have multiple workspaces each tailored in its own way Choose a location where you want to store your files then click OK Welcome to Eclipse The first time you launch Eclipse you will be presented with a welcome screen From here you can access an overview to the platform tutorials sample code etc Click on the arrow on the right to get to the actual IDE Eclipse IDE Components Perspective Switcher Menubars Full drop down menus plus quick access to common functions We can switch between various perspectives here Task List Pane This contains a list of tasks to complete Editor Pane This is where we edit our source code Package Explorer Pane Outline Pane This is where our projects files are listed This contains a hierarchical view of a source file Miscellaneous Pane Various components can appear in this pane typically this contains a console and a list of compiler problems Creating a New Project All code in Eclipse needs to live under a project To create a project File New Java Project Creating a New Project continued Enter a name for the project then click Finish Creating a New Project continued The newly created project should then appear under the Package Explorer The src folder Eclipse automatically creates a folder to store your source code in called src Creating a Class To create a class simply click on the New button then select Class Creating a Class continued This brings up the new class wizard From here you can specify the following Package Class name Superclass Whether or not to include a main Etc Fill in necessary information then click Finish to continue The Created Class As you can see a number of things have now happened Directory structure for package and actual java file created automatically Source is loaded into the editor pane already stubbed out Source displayed in a hierarchical fashion listing each method name Compiling Source Code One huge feature of Eclipse is that it automatically compiles your code in the background You no longer need to go to the command prompt and compile code directly This means that errors can be corrected when made We all know that iterative development is the best approach to developing code but going to shell to do a compile can interrupt the normal course of development This prevents going to compile and being surprised with 100 errors Example Compilation Error This code contains a typo in the println statement Packages Classes with errors are marked with a red X Often Eclipse may have suggestions on how to fix the problem if so a small light bulb will be displayed next to the line of offending code Position in file is marked with a red line 1 click allows you to jump to line with error Error underlined with red squiggly line just like spelling errors in many word processors Methods with errors are marked with a red X The Problems tab will contain a tabular representation of all errors across all files of all open projects Example Compilation Error continued When clicking on the light bulb Eclipse suggests changing printn to either print or println Running Code An easy way to run code is to right click on the class and select Run As Java Application Running Code continued The output of running the code can be seen in the Console tab in the bottom pane Run Configuration Advanced options for executing a program can be found by right clicking the class then clicking Run As Run Run Configuration continued Here you can change add any of the following JVM arguments Command line arguments Classpath settings Environment variables Which JVM to use Re Running Code After you run the code a first time you can re run it just by selecting it from the run drop down menu Debugging Code Eclipse comes with a pretty good built in debugger You can set break points in your code by double clicking in the left hand margin break points are represented by these blue bubbles Debugging Code continued An easy way to enter debug mode is to right click on the class and select Debug As Java Application Debugging Code Continued The first time you try to debug code you will be presented with the following dialog Eclipse is asking if you want to switch to a perspective that is more suited for debugging click Yes Eclipse has many perspectives based on what you are doing by default we get the Java perspective Debug Perspective These buttons allow you to step through the code Note new Debug perspective click Java to return to