[code] Project roots illustration

project_model/META-INF/plugin.xml

@@ -25,6 +25,9 @@
   </project-components>
 
   <actions>
-    <!--Add your actions here-->
+    <action id="ProjectModel.SourceRoots" class="com.intellij.plugins.project.model.ShowSourceRootsActions" text="Show Source Roots"
+            description="Illustrates how to get source roots">
+      <add-to-group group-id="ToolsMenu" anchor="after"/>
+    </action>
   </actions>
 </idea-plugin>

project_model/src/com/intellij/plugins/project/model/ShowSourceRootsActions.java

@@ -0,0 +1,33 @@
+package com.intellij.plugins.project.model;
+
+import com.intellij.openapi.actionSystem.AnAction;
+import com.intellij.openapi.actionSystem.AnActionEvent;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.roots.ProjectRootManager;
+import com.intellij.openapi.ui.Messages;
+import com.intellij.openapi.vfs.VirtualFile;
+
+/**
+ * @author Anna Bulenkova
+ */
+public class ShowSourceRootsActions extends AnAction {
+    @Override
+    public void actionPerformed(final AnActionEvent anActionEvent) {
+        Project project = anActionEvent.getProject();
+        if (project == null) return;
+        String projectName = project.getName();
+        StringBuilder sourceRootsList = new StringBuilder();
+        VirtualFile[] vFiles = ProjectRootManager.getInstance(project).getContentSourceRoots();
+        for (VirtualFile file : vFiles) {
+            sourceRootsList.append(file.getUrl()).append("\n");
+        }
+        Messages.showInfoMessage("Source roots for the " + projectName + " plugin:\n" + sourceRootsList, "Project Properties");
+    }
+
+    @Override
+    public void update(final AnActionEvent e) {
+        boolean visibility = e.getProject() != null;
+        e.getPresentation().setEnabled(visibility);
+        e.getPresentation().setVisible(visibility);
+    }
+}