COMP 14 Introduction to ProgrammingLast Week of ClassAdvanced GUIGUIsInheritanceExtending JFrameNext StepSlide 8BigGUI.javaAdding ThingsLayout ManagersBorderLayoutSlide 13JLabelsAdding LabelsSlide 16Slide 17ColorsAdding ImagesText Position Relative to IconSlide 21To doCOMP 14Introduction to ProgrammingMiguel A. OtaduyJune 7, 2004Last Week of Class•Basic programming concepts–Review–Finish assignment 6•Java applets–Compose a web page with a Java applet•Advance GUI (beyond JOptionPane)•HTMLAdvanced GUI•class JFrame–Methods–Concept of Inheritance–Events•class JAppletGUIs•We used JOptionPane to create a GUI Calculator using dialog boxes.•We can create more complex GUIs using Java.Inheritance•JFrame is a class provided by the package javax.swing•Instead of instantiating an object of the JFrame class, we're going to extend the JFrame class (called inheritance).•The new class "inherits" features (including methods and variables) from the existing class -- big time-saver!•We can use all of the methods and variables from JFrame, while adding our own.Extending JFrame•Use the modifier extends, which is a reserved word•JFrame is the superclass•BigGUI is the subclass•It is ok to learn the recipepublic class BigGUI extends JFrame{}Next Step•We'll need a constructor for BigGUI–set the window title setTitle–set the window size setSize–set the default operation when the close button is pressed setDefaultCloseOperation–display the window setVisible(true)•We'll need a main method–create an object of the BigGUI class (which will call the constructor)import javax.swing.*; // needed for JFramepublic class BigGUI extends JFrame{private final static String TITLE = “Big GUI";private final static int WIDTH = 700;private final static int HEIGHT = 600;public BigGUI() // constructor{setTitle(TITLE);setSize(WIDTH, HEIGHT);setDefaultCloseOperation(EXIT_ON_CLOSE);setVisible(true);}public static void main(String[] args){BigGUI gui = new BigGUI();}}BigGUI.java•Create JFrame and test.JFramecontent paneAdding Things•Access the content pane so we can add things (buttons, labels, images)–Container class is provided by the java.awt package–add import statement for java.awt•Then, we set the layout type and add things to the content paneContainer content = getContentPane();Layout Managers•FlowLayout–default–components are added left to right, top to bottom•BorderLayout–consists of NORTH, SOUTH, EAST, WEST, CENTER regions–size of CENTER region depends on the number of components in the EAST and WEST regions•GridLayout–define number of rows and columns to get equally sized cells–cells are filled left to right, top to bottomBorderLayout•Select layout for BigGUI as BorderLayout•When adding components with BorderLayout, you have to specify the section (using NORTH, SOUTH, EAST, WEST, CENTER constants from BorderLayout class)content.setLayout(new BorderLayout());content.add(item, BorderLayout.SECTION);BigGUI.java•Get content pane and set layout.JLabels•We'll identify the regions of the BorderLayout with labels (text areas)•JLabel is a region of text–can be assigned an alignment (left-justified, right-justified, centered)•Text can be changed with setText methodJLabel northLabel = new JLabel ("NORTH", SwingConstants.CENTER);JLabel southLabel = new JLabel ("SOUTH");northLabel.setText ("Changed Text");Adding LabelsContainer content = getContentPane();content.setLayout (new BorderLayout());JLabel northLabel = new JLabel ("NORTH", SwingConstants.RIGHT);content.add (northLabel, BorderLayout.NORTH);JLabel southLabel = new JLabel ("SOUTH");content.add (southLabel, BorderLayout.SOUTH);JLabel westLabel = new JLabel ("WEST", SwingConstants.CENTER);content.add (westLabel, BorderLayout.WEST);Adding Labels•After adding stuff to the content pane...setVisible(true);BigGUI.java•Add labels.Colors•Set the background color of the content pane•Set the foreground color of the text (JLabels)•Use Color class from the java.awt package•Available colors pg. 734–constants (but lowercase)•Methods–darker() - darkens the color–brighter() - brightens the colorcontent.setBackground(Color.blue.darker().darker());northLabel.setForeground(Color.white);Adding Images•We can create images and associate them with labels•ImageIcon–use JPG or GIF images•Use setIcon method from JLabel classcenterLabel.setIcon (image);ImageIcon image = new ImageIcon ("img/0.gif");filenamelabel.setVerticalTextPosition(vposition);label.setHorizontalTextPosition(hposition);Text Position Relative to IconSwingConstants.LEFTSwingConstants.CENTERSwingConstants.RIGHTSwingConstants.TOPSwingConstants.CENTERSwingConstants.BOTTOMBigGUI.java•Add icon.To do•Read ch. 6: pp 282-290 (important)•Get AFS access•Homework 6•Homework 7 will be