COMP 14 Introduction to Programming Miguel A Otaduy June 7 2004 Last Week of Class Basic programming concepts Review Finish assignment 6 Java applets Compose a web page with a Java applet Advance GUI beyond JOptionPane HTML Advanced GUI class JFrame Methods Concept of Inheritance Events class JApplet GUIs 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 public class BigGUI extends JFrame JFrame is the superclass BigGUI is the subclass It is ok to learn the recipe 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 JFrame public class BigGUI private final private final private final extends JFrame static String TITLE Big GUI static int WIDTH 700 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 JFrame content pane Adding Things Access the content pane so we can add things buttons labels images Container content getContentPane 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 pane 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 bottom BorderLayout Select layout for BigGUI as BorderLayout content setLayout new BorderLayout When adding components with BorderLayout you have to specify the section using NORTH SOUTH EAST WEST CENTER constants from BorderLayout class 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 leftjustified right justified centered JLabel northLabel new JLabel NORTH SwingConstants CENTER JLabel southLabel new JLabel SOUTH Text can be changed with setText method northLabel setText Changed Text Adding Labels Container 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 color content 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 filename ImageIcon image new ImageIcon img 0 gif Use setIcon method from JLabel class centerLabel setIcon image Text Position Relative to Icon label setVerticalTextPosition vposition label setHorizontalTextPosition hposition SwingConstants TOP SwingConstants CENTER SwingConstants BOTTOM SwingConstants LEFT SwingConstants CENTER SwingConstants RIGHT BigGUI java Add icon To do Read ch 6 pp 282 290 important Get AFS access Homework 6 Homework 7 will be assigned
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