Intro to Java Java Applications Swing Class Graphics

Java Outline Today – Intro and Applications – GUI Client / Server RMI, JDBC 2

JAVA Implementation 3 Java program VM Java Cmds Java program VM Java Cmds Java program VM Java Cmds SPARCPowerPCIntel

Operations Environments Applications program (~DOS window) – supports file access Applet (browser) – no longer generally supported – supports Internet linkages. 4

Building Java Applications Using Java Development Kit Get a copy of the JDK ( etc.) Install the development kit (tools and classes) Create MyApp.java source file – text editor (notepad, etc.) – winedit, Café, etc. Compile.java file to create.class file – javac MyApp.java Run application (.class file) through java VM – java MyApp 5

Building Java Applications Using Java IDEs NetBeans – Available from netbeans.org Eclipse – Available from jCreator le – available from jcreator.com – jcreator pro – academic license $35 jDeveloper – available from tools/jdev many others

Sample Java App 7 G:\Data\Java\MyHelloApp>type MyHelloApp.java class MyHelloApp { public static void main (String argv[]) { String message[] = new String[2]; message[0] = "Welcome to CS423"; message[1] = "The subject is JAVA!"; System.out.println (message[0]); System.out.println (message[1]); }

MyHelloApp Implementation 8 MyHelloApp.java MyHelloApp.class VM machine code MyHelloApp.class Java compiler Java byte code

Sample Java App 9 G:\Data\Java\MyHelloApp>javac MyHelloApp.java G:\Data\Java\MyHelloApp>java MyHelloApp Welcome to CS423 The subject is JAVA! G:\Data\Java\MyHelloApp>

MyHelloApp.class

Get Input from User 11 import java.io.*; class InputApp { InputApp () { DataInputStream dis = new DataInputStream (System.in); String sIn = " "; String sOut = " "; File fIn; File fOut; FileInputStream fis; FileOutputStream fos; int iNumBytesRead; byte[] ab;

Get Input from User 12 System.out.println ("* *"); System.out.print ("Enter Source File Name Here: "); System.out.flush (); try {sIn = dis.readLine ();} catch (Exception e) {System.out.println ("Exception on input file name" + e);} System.out.print("Enter Destination File Name Here: "); System.out.flush (); try {sOut = dis.readLine ();} catch (Exception e) {System.out.println ("Exception on output file name" + e);}

Get Input from User 13 try { fIn = new File (sIn); fis = new FileInputStream (fIn); fOut = new File (sOut); fos = new FileOutputStream (fOut); ab = new byte[2048]; while ((iNumBytesRead = fis.read (ab)) != -1) { fos.write (ab, 0, iNumBytesRead); } fis.close (); fos.close (); } catch (Exception e) {System.out.println ("Exception during copy: " + e); }

Get Input from User 14 System.out.println ("Data copied from " + sIn + " to " + sOut); System.out.println ("* *"); } public static void main (String args[]) { new InputApp (); }

Get Input from User 15 G:\Data\Java\InputApp>java InputApp * * Enter Source File Name Here: books_db.txt Enter Destination File Name Here: My_list.txt Data copied from books_db.txt to My_list.txt * * G:\Data\Java\InputApp>

Swing Components Defined in package javax.swing – Pure Java components AWT components tied to local platform GUI – UNIX java windows look like X windows – Windows java windows look like Windows windows (??) – etc. Swing defines a common look and feel for Java.

Product.java // From Java: How to Program - Deitel and Deitel // Calculate the product of three integers import javax.swing.JOptionPane; public class Product { public static void main( String args[] ) { int x, y, z, result; String xVal, yVal, zVal; xVal = JOptionPane.showInputDialog( "Enter first integer:" ); yVal = JOptionPane.showInputDialog( "Enter second integer:" ); zVal = JOptionPane.showInputDialog( "Enter third integer:" );

Product.java x = Integer.parseInt( xVal ); y = Integer.parseInt( yVal ); z = Integer.parseInt( zVal ); result = x * y * z; JOptionPane.showMessageDialog( null, "The product is " + result ); System.exit( 0 ); }

Product Output(s)

JOptionPane Similar to windows message boxes Types of Option Panes: showConfirmDialog(null,message,title,optionType,msgType); Asks a confirming question, like yes/no/cancel. showInputDialog(message); Prompt for some input. showMessageDialog(null, message); Tell the user about something that has happened. showOptionDialog(....); The Grand Unification of the above three. 20

Additional Swing Options JOptionPane.showMessageDialog(null, "This is an alert", "Alert", JOptionPane.ERROR_MESSAGE); JOptionPane.showConfirmDialog(null, "Is that your final answer?", "Choice Dialog", JOptionPane.YES_NO_OPTION);

Additional Swing Options Object[] options = { "Lady", "Tiger" }; choice = JOptionPane.showOptionDialog(null, "What will it be -\nThe Lady or the Tiger?", "Decision", JOptionPane.DEFAULT_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options[0]); if (choice == 0) JOptionPane.showMessageDialog( null, "You chose the Lady", "Result", JOptionPane.PLAIN_MESSAGE ); else JOptionPane.showMessageDialog( null, "You chose the Tiger", "Result", JOptionPane.PLAIN_MESSAGE );

Additional Swing Options Object[] possibleValues = { "First", "Second", "Third" }; Object selectedValue = JOptionPane.showInputDialog(null, "Choose one", "Input", JOptionPane.INFORMATION_MESSAGE, null, possibleValues, possibleValues[0]);

Graphics in Applications Must include a main() method Must extend the AWT Frame class, or swing JFrame class 24

HelloWorldWindow 25 import java.awt.*; import java.awt.event.*; public class HelloWorldWindow implements WindowListener { public HelloWorldWindow() { myFrame f=new myFrame(); f.addWindowListener (this); } public void windowClosing(WindowEvent e) { System.out.println ("Closing Window"); System.exit(0); }

HelloWorldWindow class myFrame extends Frame{ myFrame() { this.setSize(300, 200); this.show(); } public void paint(Graphics g) { String str = "A Windows version of Hello, World"; g.drawString(str, 25, 75); } public static void main(String[] args) { Frame f = new HelloWorldWindow(); f.resize(300, 200); f.show(); }

HelloWorldWindow Output

public void paint (Graphics g) Provides an initial presentation of Graphics Works on Graphics object – (like device context). – Place to store settings for screen output (text, images. etc.) Must be regenerated following changes. 28

Event Driven Programming Operating System recognizes an event Sends a signal to appropriate object Object receives event notification and calls appropriate function public void windowClosing(WindowEvent e) { System.out.println ("Closing Window"); System.exit(0); } 29

Object Layout BorderLayout (default for Frames) FlowLayout (default for Panels) GridLayout GridbagLayout CardLayout Fixed: – object.reshape (x, y, width, height); 30

nuTextTest Example Linux Windows

NuTextTest2.java import javax.swing.*; import java.awt.*; import java.awt.event.*; public class NuTextTest2 extends JFrame { public NuTextTest2() { setTitle("NuTextTest2"); Container p = getContentPane();; p.setLayout(new FlowLayout()); TickButton = new Button("Tick"); p.add(TickButton); TickButton.addActionListener( new ActionListener() { public void actionPerformed (ActionEvent e) { int minutes = Integer.parseInt(minuteField.getText()); minutes += 1; String min = String.valueOf(minutes); minuteField.setText(min); } } //end of ActionListener ); //end of TickButton

NuTextTest2.java SetTime = new Button("Set Time"); p.add(SetTime); SetTime.addActionListener( new ActionListener() { public void actionPerformed (ActionEvent e) { String tim = hourField.getText()+ ":" + minuteField.getText(); timeField.setText(tim); } );

NuTextTest2.java hourField = new TextField("12", 3); p.add(hourField); minuteField = new TextField("00", 3); p.add(minuteField); timeField = new TextField("", 12); p.add(timeField); setSize (400,100); show (); }//end of NuTextTest2 (constructor) private TextField hourField; private TextField minuteField; private TextField timeField; private Button TickButton; private Button SetTime;

NuTextTest2.java public static void main(String[] args) { NuTextTest2 app = new NuTextTest2(); app.addWindowListener( new WindowAdapter() { public void windowClosing( WindowEvent e ) { System.exit( 0 ); } ); }//end of main() }//end of program

Summary Java is: – Platform independent – Object-oriented – Dynamic – Flexible – used in many different domains – Command line or graphical