Last modified by cds on 2025/01/30 12:03
<
From version < 15.1 >
edited by cds
on 2012/10/24 12:13
To version < 17.1 >
edited by cds
on 2012/10/24 12:40
>
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23 23  
24 24  Over the course of this tutorial, you will be writing a bit of code. Here's a few rules we ask you to follow:
25 25  
26 -* All your Java code should be in packages with the prefix {{code language="none"}}de.cau.cs.rtprakt.login{{/code}}, where {{code language="none"}}login{{/code}} is your login name as used for your email address at the institute. From now on, this rule will apply to all tutorials. Once we start with the actual practical projects, we will choose another package name.
26 +* All your Java code should be in packages with the prefix {{code language="none"}}de.cau.cs.rtprak.login{{/code}}, where {{code language="none"}}login{{/code}} is your login name as used for your email address at the institute. From now on, this rule will apply to all tutorials. Once we start with the actual practical projects, we will choose another package name.
27 27  * All Java classes, fields, and methods should be thoroughly commented with the standard [[Javadoc>>url:http://download.oracle.com/javase/1.5.0/docs/tooldocs/windows/javadoc.html#javadoctags||shape="rect"]] comment format. Javadoc comments are well supported by Eclipse, providing code completion, syntax highlighting, and further features to help you. The code inside your methods should also be well commented. Try to think about what kinds of information would help someone unfamiliar with your code understand it.
28 28  * As you will already have noticed during the first tutorial, our tutorials use Turing machines as the underlying theme. This is partly because we're computer scientists and computer scientists are expected to choose computer sciency examples, but mostly because Turing machines work great as examples for the different kinds of topics we will be covering with you. You may thus want to take some time to read up again on the topic. [[Wikipedia>>url:http://en.wikipedia.org/wiki/Turing_machine||shape="rect"]] or the material of your Theoretical Computer Science lecture might be a great start.
29 29  * During this tutorial, we will be using Git mostly from the command line instead of using Eclipse's built-in Git support. This is because we've found Eclipse's Git support to be too unstable and buggy for us to trust it completely.
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84 84  
85 85  1. //New// -> //Project...//
86 86  1. In the project wizard, choose //Plug-in Project// and click //Next//.
87 -1. As the project name, enter {{code language="none"}}de.cau.cs.rtprakt.login.simple{{/code}}. Uncheck //Use default location// (which would put the project into your workspace), and put it into your local clone of the Git repository instead (the //Location// should read something like {{code language="none"}}/path/to/git/repository/de.cau.cs.rtprakt.login.simple{{/code}}). Click //Next//.
87 +1. As the project name, enter {{code language="none"}}de.cau.cs.rtprak.login.simple{{/code}}. Uncheck //Use default location// (which would put the project into your workspace), and put it into your local clone of the Git repository instead (the //Location// should read something like {{code language="none"}}/path/to/git/repository/de.cau.cs.rtprak.login.simple{{/code}}). Click //Next//.
88 88  1. As the name, enter {{code language="none"}}Simple (login){{/code}}. Also, make sure that //Generate an activator// and //This plug-in will make contributions to the UI// are both checked. Click //Finish//. (Eclipse might ask you whether you want to switch to the //Plug-in Development Perspective//, which configures Eclipse to provide the views that are important for plug-in development. Choose //Yes//. Or //No//. It won't have a big influence on your future...)
89 89  1. Eclipse has now created your new plug-in and was nice enough to open the //Plug-in Manifest Editor//, which allows you to graphically edit two important files of your plugin: {{code language="none"}}plugin.xml{{/code}} and {{code language="none"}}META-INF/MANIFEST.MF{{/code}}. (By the way, this would be a great time to research the editor and the two files online.) Basically, those two files provide information that tell Eclipse what other plug-ins your plug-in needs and how it works together with other plug-ins by providing extensions and extension points. Our new plug-in will depend on two other plug-ins, so switch to the //Dependencies// tab of the editor and add dependencies to {{code language="none"}}org.eclipse.ui.editors{{/code}} and {{code language="none"}}org.eclipse.jface.text{{/code}}. Save the editor and close it. (You can always reopen it by opening one of the two mentioned files from the //Package Explorer//.)
90 90  1. Tell Eclipse that the project is inside a Git repository. Right-click on the project, click //Team//, and click //Share Project//. Select Git as the repository type and click //Next//. The repository information should appear and you should be able to simply click //Finish//.
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94 94  We will now create the class that implements the simple text editor. There won't be any programming involved here since we're lazy; instead, we will just inherit from an existing simple text editor.
95 95  
96 96  1. //New// -> //Class//.
97 -1. Package: {{code language="none"}}de.cau.cs.rtprakt.login.simple.editors{{/code}}. Name: {{code language="none"}}SimpleEditorPart{{/code}}. Superclass: {{code language="none"}}org.eclipse.ui.editors.text.TextEditor{{/code}}. Click //Finish//.
97 +1. Package: {{code language="none"}}de.cau.cs.rtprak.login.simple.editors{{/code}}. Name: {{code language="none"}}SimpleEditorPart{{/code}}. Superclass: {{code language="none"}}org.eclipse.ui.editors.text.TextEditor{{/code}}. Click //Finish//.
98 98  
99 99  == Register the Editor ==
100 100  
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103 103  1. Copy [[the attached file>>attach:turing-file.gif]] to a new subfolder icons in the plug-in folder (right-click the plug-in folder in the //Package Explorer// and choose //New// -> //Folder...//). You can copy the file by importing it from inside Eclipse (//File// -> //Import...// -> //File System//) or by copying it from outside Eclipse and refreshing the plug-in project afterwards (right-click the plug-in folder in the //Package Explorer// and choose //Refresh).//
104 104  1. Open the //Plug-in Manifest Editor// again and switch to the //Extensions// tab.
105 105  1. Click //Add...//, choose the {{code language="none"}}org.eclipse.ui.editors{{/code}} extension point and click //Finish//.
106 -1. The extension point is now shown in the list of extensions, along with an //editor// extension. Select that extension and edit its details using the fields on the right. Set the ID to {{code language="none"}}de.cau.cs.rtprakt.login.simple.editor{{/code}}, the name to {{code language="none"}}Simple Text Editor{{/code}}, the icon to {{code language="none"}}icons/turing-file.gif{{/code}}, the extensions to {{code language="none"}}simple{{/code}}, the class to {{code language="none"}}de.cau.cs.rtprakt.login.simple.editors.SimpleEditorPart{{/code}}, and the default to {{code language="none"}}true{{/code}}.
106 +1. The extension point is now shown in the list of extensions, along with an //editor// extension. Select that extension and edit its details using the fields on the right. Set the ID to {{code language="none"}}de.cau.cs.rtprak.login.simple.editor{{/code}}, the name to {{code language="none"}}Simple Text Editor{{/code}}, the icon to {{code language="none"}}icons/turing-file.gif{{/code}}, the extensions to {{code language="none"}}simple{{/code}}, the class to {{code language="none"}}de.cau.cs.rtprak.login.simple.editors.SimpleEditorPart{{/code}}, and the default to {{code language="none"}}true{{/code}}.
107 107  1. Save the manifest editor.
108 108  
109 109  == Test the Editor ==
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125 125  The next task consists of creating a view that is able to display the state of a Turing Machine. We will do this using a table with one column, where each row represents an entry on the tape of the Turing Machine. The tape shall be infinite to one side, and the position of the read/write head shall be movable by two buttons. The content of the tape shall be determined by the currently active instance of our simple text editor.
126 126  
127 127  {{info title="Hint"}}
128 -In this tutorial, we will be making use of the Standard Widget Toolkit (SWT) to build a user interface. It might be a good idea now to search for an introduction to SWT concepts on the Internet now before you proceed.
128 +In this tutorial, we will be making use of the Standard Widget Toolkit (SWT) and JFace to build a user interface. It might be a good idea now to search for an introduction to SWT and JFace concepts on the Internet before you proceed.
129 129  {{/info}}
130 130  
131 131  == Creating the View Class ==
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132 132  
133 133  We will start by creating a class that will define the view.
134 134  
135 -1. Create a class {{code language="none"}}TapeViewPart{{/code}} in a new package {{code language="none"}}de.cau.cs.rtprakt.login.simple.views{{/code}} that extends the [[ViewPart>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/ui/part/ViewPart.html||shape="rect"]] class.
135 +1. Create a class {{code language="none"}}TapeViewPart{{/code}} in a new package {{code language="none"}}de.cau.cs.rtprak.login.simple.views{{/code}} that extends the [[ViewPart>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/ui/part/ViewPart.html||shape="rect"]] class. (make sure that in the //New Java Class// wizard, the option //Inherited abstract methods// is checked.)
136 136  1. Add a private field {{code language="none"}}tableViewer{{/code}} of type [[TableViewer>>url:http://help.eclipse.org/juno/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/jface/viewers/TableViewer.html||shape="rect"]].
137 137  1. (((
138 -Your TableViewPart contains a still empty method createPartControl. This method will be responsible for creating the user interface components of your view. Add the following code to create the table we want to display:
138 +Your {{code language="none"}}TableViewPart{{/code}} contains a still empty method {{code language="none"}}createPartControl{{/code}}. This method will be responsible for creating the user interface components of your view. Add the following code to create the table we want to display:
139 139  
140 -{{code title="createPartControl(...)" linenumbers="true" language="java" collapse="true"}}
140 +{{code title="createPartControl(...)" language="java"}}
141 141  Table table = new Table(parent, SWT.BORDER);
142 142  TableColumn column = new TableColumn(table, SWT.NONE);
143 143  column.setWidth(80);
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145 145  {{/code}}
146 146  )))
147 147  1. (((
148 -The setFocus method controls what happens when your part gets the focus. Make sure the focus will then automatically be set to the table by adding the following code:
148 +The {{code language="none"}}setFocus{{/code}} method controls what happens when your part gets the focus. Make sure the focus will then automatically be set to the table by adding the following code:
149 149  
150 -{{code title="setFocus(...)" linenumbers="true" collapse="true"}}
150 +{{code title="setFocus(...)"}}
151 151  tableViewer.getControl().setFocus();
152 152  {{/code}}
153 153  )))
154 154  
155 -
155 +== Create the View Extension ==
156 156  
157 -
157 +We will now have to register our new view with Eclipse so that it can be seamlessly integrated into the workbench.
158 158  
159 -
159 +1. Copy the three files [[attach:tape_head.gif]], [[attach:head_present.gif]], and [[attach:head_absent.gif]]to the {{code language="none"}}icons{{/code}} subfolder of your plug-in as you did it before. (You might need to refresh your project again if you did the copying outside of Eclipse.)
160 +1. Open the {{code language="none"}}plugin.xml{{/code}} file in the //Plugin Manifest Editor// and switch to the //Extensions// tab.
161 +1. Click //Add// to add a new extension for the extension point {{code language="none"}}org.eclipse.ui.views{{/code}}. Right-click the newly added extension and add a new {{code language="none"}}view{{/code}} element through the //New// menu.
162 +1. Set the view element's properties as follows: ID {{code language="none"}}de.cau.cs.rtprak.login.simple.view{{/code}}, name {{code language="none"}}Tape{{/code}}, class {{code language="none"}}de.cau.cs.rtprak.login.simple.views.TapeViewPart{{/code}}, category {{code language="none"}}org.eclipse.ui{{/code}}, icon {{code language="none"}}icons/tape_head.gif{{/code}}.
160 160  
164 +When you start the application, you should now be able to open your view by clicking //Window// -> //Show View// -> //Other//.
165 +
166 +== Add Content and Label Providers ==
167 +
168 +The idea of JFace viewers is to abstract a bit from the underlying widget (in our case, the table) and instead work on data models that are to be viewed. Instead of adding items to the table directly, the table viewer is supplied with an input object, a content provider, and a label provider. The content provider allows the viewer to make sense of the input object and basically allows the viewer to access the input object's data. The label provider translates each item of data into text and icons that can be used to present the item to the user in the table.
169 +
170 +We will now create content and label providers to do just that.
171 +
172 +1. (((
173 +Create a class {{code language="none"}}TuringTape{{/code}} in a new package {{code language="none"}}de.cau.cs.rtprak.login.simple.model{{/code}} with the following fields:
174 +
175 +{{code title="Fields" language="java"}}
176 +private int headPosition = 1;
177 +private StringBuffer text = new StringBuffer();
178 +{{/code}}
179 +
180 +Also add corresponding getter and setter methods. (You can simply right-click somewhere in the class and choose //Source// -> //Generate Getters and Setters//.)
181 +)))
182 +1. (((
183 +Add two constants to the class:
184 +
185 +{{code title="Constants" language="java"}}
186 +public static final char START_CHAR = '\u25b7';
187 +public static final char BLANK_CHAR = '\u25fb';
188 +{{/code}}
189 +)))
190 +1. Add a method {{code language="none"}}getCharacter(int pos){{/code}} that calculates the tape character at position {{code language="none"}}pos{{/code}} as follows:\\
191 +1*. For {{code language="none"}}pos == 0{{/code}}, return the character {{code language="none"}}START_CHAR{{/code}}.
192 +1*. For {{code language="none"}}pos > text.length(){{/code}}, return the character {{code language="none"}}BLANK_CHAR{{/code}}.
193 +1*. Otherwise, return the text character at index {{code language="none"}}pos - 1{{/code}}.
194 +1. Add a private field tape of type {{code language="none"}}TuringTape{{/code}} to {{code language="none"}}TapeViewPart{{/code}} and initialize it with a new instance.
195 +1. Create a class {{code language="none"}}TapeData{{/code}} in {{code language="none"}}de.cau.cs.rtprak.login.simple.views{{/code}} with two fields {{code language="none"}}int index{{/code}} and {{code language="none"}}char character{{/code}}, and add a constructor for initialization as well as corresponding getter methods.
196 +
161 161  
162 162  
163 163  = Creating an Extension Point =
Confluence.Code.ConfluencePageClass[0]
Id
... ... @@ -1,1 +1,1 @@
1 -2982287
1 +2982292
URL
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1 -https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982287/The Plug-in Architecture of Eclipse
1 +https://rtsys.informatik.uni-kiel.de/confluence//wiki/spaces/WS12EclPract/pages/2982292/The Plug-in Architecture of Eclipse

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