Using Eclipse Ide

[Jennifer Curtis]

The Eclipse IDE (integrated development environment) provides strong support for Java developer.In 2022 the Eclipse IDE has approximately one millions downloads per month which makes it one of the leading IDEs for Java development.

The Eclipse IDE for Java Developers distribution is designed to support standard Java development.It includes support for the Maven and Gradle build system and support for the Git version control system.

Other IDE tools are also re-using components like the powerful code editor Visual Studio Code (Code) from Microsoft uses the Eclipse Java compiler for its Java support.Also the Eclipse IDE re-uses tools designed for Code based on the language server protocol defined by Microsoft.

On Linux you have to unzip it before you can start it.On Mac the installer is delivered as a packaged application and can be installed and started via regular Mac installation procedures.On Windows and Mac you can run it directly via the delivered executable / package application.

The workspace is the physical location (file path) for storing meta-data and (optional) your development artifacts.The meta-data stored for the workspace contains preferences settings, plug-in specific meta data, logs etc.

Your projects, source files, images and other artifacts can be stored inside or outside your workspace.For example, if you use Git as version control system, you typically would store the Git repositories outside of the workspace.

Eclipse provides different perspectives for different tasks.The available perspectives_depend on your installation.For Java development you usually use the Java Perspective, but Eclipse has much more predefined perspectives, e.g., the Debug perspective.

The following picture shows the default Java perspective.The Package Explorer view is on the left.In the middle you see the open editors.Several editors are stacked in the same container and you can switch between them by clicking on the corresponding tab.Via drag and drop you can move an editor to a new position in the Eclipse IDE.

To the right and below the editor area you find more views which were considered useful by the developer of the perspective.For example, the Javadoc view shows the Javadoc of the selected class or method.

For example, the Project Explorer view allows you to browse and modify files of Eclipse projects.If you rename a file via the Project Explorer the file name is directly changed without having to save.

Editors are typically used to modify a single data element, for example a text file.To apply these changes to the underlying data mode, you need to select save from the menu or the toolbar.A editor with unsaved data (a dirty editor) is marked with an asterisk left to the name of the modified file.

An Eclipse project contains source, configuration and binary files related to a certain task.It groups them into buildable and reusable units.An Eclipse project can have natures assigned to it which describe the purpose of this project.For example, the Java nature defines a project as Java project.Projects can have multiple natures combined to model different technical aspects.

It is also used to change the structure of your project.For example, you can rename files or move files and folders via drag and drop.A right-click on a file or folder shows you the available options.

The Problems view shows errors and warning messages.Sooner or later you will run into problems with your code or your project setup.To view the problems in your project, you can use the Problems view which is part of the standard Java perspective.If this view is closed, you can open it via Window Show View Problems.

The messages which are displayed in the Problems view can be configured via the drop-down menu of the view.For example, to display the problems from the currently selected project, select Configure Contents and set the Scope to On any element in the same project.

A good naming convention is to use the same name for the top level package and the project.For example, if you name your project com.example.javaproject you should also use com.example.javaproject as the top-level package name.

To run this program, include the JAR file in your classpath.The classpath defines which Java classes are available to the Java runtime.You can add a JAR file to the classpath with the -classpath option.

Create the following Tester class in the *.main package.This is a simple class without the usage of any unit testing framework like JUnit.The Eclipse editor should mark the created class with an error because the required import statements are missing.

The primary way of navigating through your project is the Package Explorer or alternatively the Project Explorer view.You can open nodes in the tree and open a file in an editor by double-clicking on the corresponding entry in the tree hierarchy.

The Package Explorer view allows you to display the associated file from the currently selected editor.For example, if you are working on the Foo.java file in the Java editor and switch to the Java editor of the Var.java file, then the corresponding file will be selected in the Package Explorer view.

In addition, you can open any class by positioning the cursor on the class in an editor and pressing F3.Alternatively, you can press Ctrl+Shift+T.This shows the following dialog in which you can enter the class name to open it.

The Open Type Dialog also supports CamelCase like search, e.g., it matches capital letters in the class name.For example, if you would search for the OnTouchListener class you could use OTL or OToList as search term.

You can open any file from your open projects via the Open Resource dialog.You can open this dialog via the Ctrl+Shift+R shortcut.This dialog allows to enter the file name and to open or show it in a selected view.The following screenshot demonstrate the usage to open a pom.xml file from your workspace.

Quick Outline shows you an structured overview of the file you are editing.For example, for a Java class you see its methods with the option to filter.The shortcut for opening the Quick Outline is Ctrl+O.You can also reach this option, via right-click in an editor via the Quick Outline option.

Eclipse associates file extensions with the default tab.You can customize the available search tabs via the Customize button in the Search dialog.Via the Remember the last used page you can configure Eclipse to use your last tab as default.

The Search view shows the search results for the selected scope.You can double-click on a search entry to navigate to the corresponding position in the editor.The currently selected search result is also indicated via an arrow in the left border of the editor.

You can use the Ctrl+J shortcut to activate Incremental Find.This allows you to search in the current active editor for a text which is displayed in the status line as depicted by the following screenshot.Repeat Ctrl+J in order to move to the next occurrence of the current search term.

By pressing the buttons you can navigate to the related annotations.You can also use the keyboard shortcut Ctrl+. (Ctrl plus the dot sign) for selecting the next annotation or Ctrl+, (Ctrl plus the comma sign) for selecting the previous annotation.

In a lot of cases you can also use the mouse to navigate to or into an element if you press the Ctrl key.For example, press the Ctrl key and (left) click with the mouse on the name of a class to jump into the class declaration.

Closing projects saves memory in Eclipse and can reduce the build time.Eclipse ignores closed projects, e.g., all searches ignore files from closed projects.Also the Problems view does only shows errors of opened projects.This typically helps you focus your attention on the project.You can close projects via a right-click on it and by selecting the Close Project menu entry.Alternatively, if you work on a project, you can close all unrelated projects via a right-click on it and by selecting the Close Unrelated Projects menu entry.

Whenever the Eclipse Java tooling detects a problem in your code, it underlines the problematic text in the editor and create a problem marker.The problem marker is visible in the Problems View and in the editor via markers on the left side of the editor .Select the underlined text and press Ctrl+1 to see suggestions for correcting the problem.This functionality is called Quick Fix.

For example, type myBoolean = true;If myBoolean is not yet defined as a field, Eclipse highlights this statement as an error.Select the variable and press Ctrl+1.Eclipse suggests creating a field or local variable.

Quick Fixis extremely powerful. For example, it allows you tocreate newlocalvariables and fields as well as new methods and newclasses. Or itcanputtry/catch statementsaround your exceptions. Itcan alsoassign astatementto a variable and much more.

For example, Eclipse can override methods from superclasses and generate the toString(), hashcode() and equals() methods.It can also generate getter and setter methods for attributes of your Java class.

For example, to use the Rename refactoring, you can right-click on your class (in the editor or Package Explorer) and select Refactor Rename to rename your class.Eclipse will make sure that all calls in your Workspace to your class or method are renamed.

Eclipse has many more refactorings.The available options depend on the selection in the Java editor.In most cases you should get an idea of the performed action by the naming of the refactoring operation.

A useful refactoring is to mark code and create a method from the selected code.Mark now the coding of the "for" loop, right click on the selection and select Refactoring Extract Method.Use calculateSum as the name of the new method.

You can also extract strings and create constants based on thestrings. Mark forthis example the"Hello Eclipse!"string in your source code, right-click on it andselectRefactor Extract Constant. Name your new constant HELLO.

You can store JAR files directly in your project, and add them to the classpath which the Java compiler of Eclipse is using.To manage the classpath for your Eclipse, right-click on your project and select Properties.Under Java Build Path Libraries you can review and change your current classpath as depicted in the following screenshot.

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