Topic awaiting preservation: Problem with ArrayList (Java) (Page 1 of 1)

public void newURL(String url)

	{

		if (currentPage.equals(null) | | currentPage.equals(""))

		{

			//Do nothing

		}

		else 

			backHistory.add(0,currentPage);

		currentPage = url;

		forwardHistory.clear();

	}



	public String forward()

	{

		backHistory.add(0,currentPage);

		currentPage = forwardHistory.get(0);

		forwardHistory.remove(0);

		return (String)currentPage;

	}



	public String back()

	{

		forwardHistory.add(0,currentPage);

		currentPage = backHistory.get(0);

		backHistory.remove(0);

		return (String)currentPage;

	}

import javax.swing.*;

import javax.swing.event.*;

import java.awt.*;

import java.awt.event.*;

import java.net.*;

import java.io.*;



/** Very simplistic "Web browser" using Swing. Supply a URL on the 

 *  command line to see it initially, and to set the destination

 *  of the "home" button.

 *  1998 Marty Hall, [url=http://www.apl.jhu.edu/~hall/java/]http://www.apl.jhu.edu/~hall/java/[/url] 

 */



public class Browser extends JFrame implements HyperlinkListener, 

                                               ActionListener {

  public static void main(String[] args) {

    if (args.length == 0)

      new Browser("http://www.cs.sunysb.edu/~cse333/Section2/");

    else

      new Browser(args[0]);

  }



  private JIconButton homeButton, backButton, forwardButton;

  private JTextField urlField;

  private JEditorPane htmlPane;

  private String initialURL;

  private JLabel testLabel;



  /** Create a new instance of the browser history.

   */



  private BrowserHistory historyControl = new BrowserHistory();



  public Browser(String initialURL) {

    super("Daniel Curran Project 5");

    this.initialURL = initialURL;

    addWindowListener(new ExitListener());

    WindowUtilities.setNativeLookAndFeel();



    JPanel topPanel = new JPanel();

    topPanel.setBackground(Color.lightGray);



	/** Add the back and forwad buttons

	 *  to the top panel.

	 */

    homeButton = new JIconButton("home.gif");

    homeButton.addActionListener(this);



	backButton = new JIconButton("back.gif");

	backButton.setEnabled(false);

	backButton.addActionListener(this);



	forwardButton = new JIconButton("forward.gif");

	forwardButton.setEnabled(false);

	forwardButton.addActionListener(this);



    JLabel urlLabel = new JLabel("URL:");

    urlField = new JTextField(30);

    urlField.setText(initialURL);

    urlField.addActionListener(this);



	//TEST



		testLabel = new JLabel("Sizes (forward, backward): ");

		topPanel.add(testLabel);



	//TEST

	

	/** Place the new forward and back

	 *  button on the topPanel.

	 */



	topPanel.add(backButton);

	topPanel.add(forwardButton);



    topPanel.add(homeButton);

    topPanel.add(urlLabel);

    topPanel.add(urlField);



    getContentPane().add(topPanel, BorderLayout.NORTH);



    try {

        htmlPane = new JEditorPane(initialURL);



		/** Code to set the current page to the initial URL.

		 */



		historyControl.newURL(initialURL);

	    if (historyControl.backIsEmpty())

		  backButton.setEnabled(false);

	    else

		  backButton.setEnabled(true);

	    if (historyControl.forwardIsEmpty())

		  forwardButton.setEnabled(false);

	    else

		  forwardButton.setEnabled(true);



	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST



        htmlPane.setEditable(false);

        htmlPane.addHyperlinkListener(this);

        JScrollPane scrollPane = new JScrollPane(htmlPane);

        getContentPane().add(scrollPane, BorderLayout.CENTER);

    } catch(IOException ioe) {

       warnUser("Can't build HTML pane for " + initialURL 

                + ": " + ioe);

    }



    Dimension screenSize = getToolkit().getScreenSize();

    int width = screenSize.width * 8 / 10;

    int height = screenSize.height * 8 / 10;

    setBounds(width/8, height/8, width, height);

    setVisible(true);

  }



  public void actionPerformed(ActionEvent event) {

    String url = "";

    if (event.getSource() == urlField){ 

      url = urlField.getText();



	  historyControl.newURL(url);

	  if (historyControl.backIsEmpty())

		backButton.setEnabled(false);

	  else

		backButton.setEnabled(true);

	  if (historyControl.forwardIsEmpty())

		forwardButton.setEnabled(false);

	  else

		forwardButton.setEnabled(true);

	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST

	}

	else if(event.getSource() == forwardButton)

	{

	  url = historyControl.forward();

	  if (historyControl.backIsEmpty())

		backButton.setEnabled(false);

	  else

		backButton.setEnabled(true);



	  if (historyControl.forwardIsEmpty())

		forwardButton.setEnabled(false);

	  else

		forwardButton.setEnabled(true);

	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST



	}

	else if(event.getSource() == backButton)

	{

	  url = historyControl.back();



	  if (historyControl.backIsEmpty())

		backButton.setEnabled(false);

	  else

		backButton.setEnabled(true);



	  if (historyControl.forwardIsEmpty())

		forwardButton.setEnabled(false);

	  else

		forwardButton.setEnabled(true);



	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST



	}

    else  // Clicked "home" button instead of entering URL

      url = initialURL;



	  historyControl.newURL(url);

	  if (historyControl.backIsEmpty())

		backButton.setEnabled(false);

	  else

		backButton.setEnabled(true);

	  if (historyControl.forwardIsEmpty())

		forwardButton.setEnabled(false);

	  else

		forwardButton.setEnabled(true);



	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST



    try {

      htmlPane.setPage(new URL(url));

      urlField.setText(url);

    } catch(IOException ioe) {

      warnUser("Can't follow link to " + url + ": " + ioe);

    }

  }



  public void hyperlinkUpdate(HyperlinkEvent event) {

    if (event.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {

      try {

        htmlPane.setPage(event.getURL());



		historyControl.newURL(event.getURL().toExternalForm());

	    if (historyControl.backIsEmpty())

		  backButton.setEnabled(false);

	    else

		  backButton.setEnabled(true);

	    if (historyControl.forwardIsEmpty())

		  forwardButton.setEnabled(false);

	    else

		  forwardButton.setEnabled(true);



	  //TEST

	  testLabel.setText("" + historyControl.toString() + "");

      //TEST



        urlField.setText(event.getURL().toExternalForm());

      } catch(IOException ioe) {

        warnUser("Can't follow link to " 

                 + event.getURL().toExternalForm() + ": " + ioe);

      }

    }

  }



  private void warnUser(String message) {

    JOptionPane.showMessageDialog(this, message, "Error", 

                                  JOptionPane.ERROR_MESSAGE);

  }

}

import java.awt.*;

import java.awt.event.*;



/** A listener that you attach to the top-level Frame or JFrame of

 *  your application, so quitting the frame exits the application.

 *  1998-99 Marty Hall, [url=http://www.apl.jhu.edu/~hall/java/]http://www.apl.jhu.edu/~hall/java/[/url] 

 */



public class ExitListener extends WindowAdapter {

  public void windowClosing(WindowEvent event) {

    System.exit(0);

  }

}

import javax.swing.*;



/** A regular JButton created with an ImageIcon and with borders

 *  and content areas turned off.

 *  1998 Marty Hall, [url=http://www.apl.jhu.edu/~hall/java/]http://www.apl.jhu.edu/~hall/java/[/url] 

 */



public class JIconButton extends JButton {

  public JIconButton(String file) {

    super(new ImageIcon(file));

    setContentAreaFilled(false);

    setBorderPainted(false);

    setFocusPainted(false);

  }

}

import javax.swing.*;

import java.awt.*;



/** A few utilities that simplify using windows in Swing.

 *  1998-99 Marty Hall, [url=http://www.apl.jhu.edu/~hall/java/]http://www.apl.jhu.edu/~hall/java/[/url] 

 */



public class WindowUtilities {



  /** Tell system to use native look and feel, as in previous

   *  releases. Metal (Java) LAF is the default otherwise.

   */



  public static void setNativeLookAndFeel() {

    try {

      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());

    } catch(Exception e) {

      System.out.println("Error setting native LAF: " + e);

    }

  }



  public static void setJavaLookAndFeel() {

    try {

      UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());

    } catch(Exception e) {

      System.out.println("Error setting Java LAF: " + e);

    }

  }



   public static void setMotifLookAndFeel() {

    try {

      UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");

    } catch(Exception e) {

      System.out.println("Error setting Motif LAF: " + e);

    }

  }



  /** A simplified way to see a JPanel or other Container.

   *  Pops up a JFrame with specified Container as the content pane.

   */



  public static JFrame openInJFrame(Container content,

                                    int width,

                                    int height,

                                    String title,

                                    Color bgColor) {

    JFrame frame = new JFrame(title);

    frame.setBackground(bgColor);

    content.setBackground(bgColor);

    frame.setSize(width, height);

    frame.setContentPane(content);

    frame.addWindowListener(new ExitListener());

    frame.setVisible(true);

    return(frame);

  }



  /** Uses Color.white as the background color. */



  public static JFrame openInJFrame(Container content,

                                    int width,

                                    int height,

                                    String title) {

    return(openInJFrame(content, width, height, title, Color.white));

  }



  /** Uses Color.white as the background color, and the

   *  name of the Container's class as the JFrame title.

   */



  public static JFrame openInJFrame(Container content,

                                    int width,

                                    int height) {

    return(openInJFrame(content, width, height,

                        content.getClass().getName(),

                        Color.white));

  }

}