implement editor in java

See more:

Java

netbeans

editing

I am developing a simple c-editor using java and I want to add following feature in it...I have implemented for simple space and word but having issues with indention when there are curly braces(for example, if there are space separated opening braces are there,it is not working.Also, the closing braces are not properly aligned with the opening braces).
Solutions are welcomed.Here is my code which implement the indention..

import java.awt.*;
import java.awt.event.*;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.swing.*;
import javax.swing.text.*;

public class Indent extends JFrame
{
    /**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public Indent()
    {
        JTextPane textComponent = new JTextPane();
        JScrollPane scrollPane = new JScrollPane( textComponent );
        getContentPane().add( scrollPane );

        ActionMap am = textComponent.getActionMap();
        am.put(DefaultEditorKit.insertBreakAction, new IndentAction());
    }

    public static class IndentAction extends TextAction
    {
         /**
		 * 
		 */
		private static final long serialVersionUID = 1L;

		/**
         * Creates this object with the appropriate identifier.
         */
        public IndentAction()
        {
            super(DefaultEditorKit.insertBreakAction);
        }

        /**
         * The operation to perform when this action is triggered.
         *
         * @param e the action event
         */
        public void actionPerformed(ActionEvent e)
        {
            JTextComponent target = getTextComponent(e);

            if (target == null) return;

            if ((! target.isEditable()) || (! target.isEnabled()))
            {
                UIManager.getLookAndFeel().provideErrorFeedback(target);
                return;
            }

            try
            {
                //  Determine which line we are on

                Document doc = target.getDocument();
                Element rootElement = doc.getDefaultRootElement();
                int selectionStart = target.getSelectionStart();
                int line = rootElement.getElementIndex( selectionStart );
                StringBuilder indent = new StringBuilder(new String(""));
                //  Get the text for this line

                int start = rootElement.getElement(line).getStartOffset();
                int end = rootElement.getElement(line).getEndOffset();
                int length = end - start;
                String text = doc.getText(start, length);
                int offset = 0;
                boolean posBrace = text.contains("{");
                boolean closeBrace = text.contains("}");
                //  Get the number of white spaces characters at the start of the line
               
                for (offset = 0; offset < length; offset++)
                {
                    char c = text.charAt(offset);

                    if (c != ' ' && c != '\t')
                        break;
                }

                //  When splitting the text include white space at start of line
                //  else do default processing

                if (selectionStart - start > offset)
                {
                	indent.append( text.substring(0, offset) );
                    if( !posBrace )
                    {
                    	indent.insert(0, "\n");
                    }
                    else
                    {
                    	indent.insert(0, "\n\t");
                    }
                    target.replaceSelection(indent.toString() );
                    if(closeBrace)
                    {
                    	indent.deleteCharAt(indent.indexOf("\t"));
                    	target.replaceSelection(indent.toString() );
                    }
                }
                else
                    target.replaceSelection("\n");
            }
            catch(BadLocationException ble) {}
        }
    }

         public static void main(String[] args)
    {
        Indent frame =new Indent();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.setSize( new Dimension( 300, 100) );
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }
}