Patch# 3199838: selecting a node in the GUI moves the code pane to the corresponding line. Very nice

src/checkstyle/com/puppycrawl/tools/checkstyle/gui/CodeSelector.java

@@ -0,0 +1,45 @@
+package com.puppycrawl.tools.checkstyle.gui;
+
+import com.puppycrawl.tools.checkstyle.api.DetailAST;
+import java.awt.Color;
+import java.util.List;
+import javax.swing.JTextArea;
+
+public class CodeSelector
+{
+    private final DetailAST ast;
+    private final JTextArea editor;
+    private final List<Integer> lines2position;
+
+    public CodeSelector(final DetailAST ast, final JTextArea editor,
+                        final List<Integer> lines2position)
+    {
+        this.ast = ast;
+        this.editor = editor;
+        this.lines2position = lines2position;
+    }
+
+    public void select() {
+        int start = lines2position.get(ast.getLineNo()) + ast.getColumnNo();
+        int end = findLastPosition(ast);
+
+        editor.setSelectedTextColor(Color.blue);
+        editor.requestFocusInWindow();
+        editor.setSelectionStart(start);
+        editor.setSelectionEnd(end);
+        editor.transferFocusBackward();
+    }
+
+    private int findLastPosition(final DetailAST ast)
+    {
+        if (ast.getChildCount() == 0)
+        {
+            return lines2position.get(ast.getLineNo()) + ast.getColumnNo()
+                + ast.getText().length();
+        }
+        else
+        {
+            return findLastPosition(ast.getLastChild());
+        }
+    }
+}

src/checkstyle/com/puppycrawl/tools/checkstyle/gui/JTreeTable.java

@@ -65,9 +65,12 @@ import java.awt.Graphics;
 import java.awt.event.ActionEvent;
 import java.awt.event.MouseEvent;
 import java.util.EventObject;
+import java.util.List;
+
 import javax.swing.Action;
 import javax.swing.AbstractAction;
 import javax.swing.JTable;
+import javax.swing.JTextArea;
 import javax.swing.JTree;
 import javax.swing.KeyStroke;
 import javax.swing.ListSelectionModel;
@@ -83,6 +86,8 @@ import javax.swing.tree.TreeCellRenderer;
 import javax.swing.tree.TreeModel;
 import javax.swing.tree.TreePath;
 
+import com.puppycrawl.tools.checkstyle.api.DetailAST;
+
 /**
  * This example shows how to create a simple JTreeTable component,
  * by using a JTree as a renderer (and editor) for the cells in a
@@ -100,6 +105,8 @@ public class JTreeTable extends JTable
     private static final long serialVersionUID = -8493693409423365387L;
     /** A subclass of JTree. */
     protected TreeTableCellRenderer tree;
+    private JTextArea editor;
+    private List<Integer> lines2position;
 
     public JTreeTable(TreeTableModel treeTableModel)
     {
@@ -142,6 +149,10 @@ public class JTreeTable extends JTable
 
                 public void actionPerformed(ActionEvent e) {
                     final TreePath selected = tree.getSelectionPath();
+
+                    DetailAST ast = (DetailAST) selected.getLastPathComponent();
+                    new CodeSelector(ast, editor, lines2position).select();
+
                     if (tree.isExpanded(selected)) {
                         tree.collapsePath(selected);
                     }
@@ -480,4 +491,14 @@ public class JTreeTable extends JTable
             }
         }
     }
+
+    public void setEditor(JTextArea mJTextArea)
+    {
+         this.editor = mJTextArea;
+    }
+
+    public void setLinePositionMap(List<Integer> lines2position)
+    {
+        this.lines2position = lines2position;
+    }
 }

src/checkstyle/com/puppycrawl/tools/checkstyle/gui/ParseTreeInfoPanel.java

@@ -26,6 +26,8 @@ import java.awt.event.ActionEvent;
 import java.awt.event.KeyEvent;
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.TooManyListenersException;
 import javax.swing.AbstractAction;
 import javax.swing.Action;
@@ -60,6 +62,7 @@ public class ParseTreeInfoPanel extends JPanel
     private File mLastDirectory = null;
     private File mCurrentFile = null;
     private final Action reloadAction;
+    private final List<Integer>   lines2position  = new ArrayList<Integer>();
 
     private static class JavaFileFilter extends FileFilter
     {
@@ -162,6 +165,18 @@ public class ParseTreeInfoPanel extends JPanel
                 reloadAction.setEnabled(true);
 
                 final String[] sourceLines = text.toLinesArray();
+
+                // clear for each new file
+                 getLines2position().clear();
+                 // starts line counting at 1
+                 getLines2position().add(0);
+                 // insert the contents of the file to the text area
+                 for (String element : sourceLines)
+                 {
+                   getLines2position().add(mJTextArea.getText().length());
+                   mJTextArea.append(element + "\n");
+                 }
+
                 //clean the text area before inserting the lines of the new file
                 if (mJTextArea.getText().length() != 0) {
                     mJTextArea.replaceRange("", 0, mJTextArea.getText()
@@ -251,6 +266,8 @@ public class ParseTreeInfoPanel extends JPanel
 
         mJTextArea = new JTextArea(20, 15);
         mJTextArea.setEditable(false);
+        mTreeTable.setEditor(mJTextArea);
+        mTreeTable.setLinePositionMap(lines2position);
 
         final JScrollPane sp2 = new JScrollPane(mJTextArea);
         this.add(sp2, BorderLayout.CENTER);
@@ -284,5 +301,9 @@ public class ParseTreeInfoPanel extends JPanel
         SwingUtilities.invokeLater(showError);
     }
 
+    public List<Integer> getLines2position()
+    {
+      return lines2position;
+    }
 }