JRadioButton: Simpler Example

import javax.swing.*;
import java.awt.*;
import java.awt.event.*; // step 1

// Mututally exclusive == >ButtonGroup

public class JRadioButtonDemo extends JFrame //step 2
                             implements ActionListener{

  private JRadioButton rbtn1 = new JRadioButton("Ivan");
  private JRadioButton rbtn2 = new JRadioButton("Kwan Yong");
  private JButton btn = new JButton("Vote");
  
  private ButtonGroup btngrp = new ButtonGroup();

  public JRadioButtonDemo() {

    btngrp.add(rbtn1); // For making one radiobutton clickable at one time
    btngrp.add(rbtn2);
    
    rbtn1.setSelected(true); // Set Ivan to be default
    
    getContentPane().setLayout(new FlowLayout());
    getContentPane().add(rbtn1);
    getContentPane().add(rbtn2);
    getContentPane().add(btn);

    btn.addActionListener(this);//step 4:

  } //end constructor

  public void actionPerformed(ActionEvent ev){//step 3

    String name = "";
    if (ev.getSource() == btn){
      if (rbtn1.isSelected()){ // Ivan was voted
        name = "Ivan";
      }
      else if (rbtn2.isSelected()){
        name = "Kwan Yong";
      }
      
      JOptionPane.showMessageDialog(null, "You voted for " + name);
    }//end if

  } //end actionPerformed

  public static void main(String[] args) {
    JRadioButtonDemo f = new JRadioButtonDemo();
    f.setTitle("OOPG");
    f.setSize(300, 300);
    f.setVisible(true);

  } //end main
} //end class

JRadioButton: More Complicated Example

import javax.swing.*;
import java.awt.*;
import java.awt.event.*; // step 1

// Mututally exclusive == >ButtonGroup

public class JRadioButtonDemo2 extends JFrame //step 2
                             implements ActionListener{

  private JRadioButton rbtn1 = new JRadioButton("Ivan");
  private JRadioButton rbtn2 = new JRadioButton("Kwan Yong");
  private JTextArea ta1 = new JTextArea(5,30);
  private JButton btn = new JButton("Vote");
  
  private int ivan;
  private int kwanyong;

  private ButtonGroup btngrp = new ButtonGroup();

  public JRadioButtonDemo2() {

    btngrp.add(rbtn1); // For making one radiobutton clickable at one time
    btngrp.add(rbtn2);

    rbtn1.setSelected(true); // Set Ivan to be default

    getContentPane().setLayout(new FlowLayout());
    getContentPane().add(rbtn1);
    getContentPane().add(rbtn2);
    getContentPane().add(btn);
    getContentPane().add(ta1); // textarea display the no.of votes

    btn.addActionListener(this);//step 4:

  } //end constructor

  public void actionPerformed(ActionEvent ev){//step 3

    String name = "";
    if (ev.getSource() == btn){
      if (rbtn1.isSelected()){ // Ivan was voted
        name = "Ivan";
        ivan++;
      }
      else if (rbtn2.isSelected()){
        name = "Kwan Yong";
        kwanyong++;
      }

      JOptionPane.showMessageDialog(null, "You voted for " + name);
      ta1.setText("Ivan:" + ivan + "\nKwan Yong:" + kwanyong);
      
    }//end if

  } //end actionPerformed

  public static void main(String[] args) {
    JRadioButtonDemo2 f = new JRadioButtonDemo2();
    f.setTitle("OOPG");
    f.setSize(300, 300);
    f.setVisible(true);

  } //end main
} //end class

JTextArea : setText, getText and append methods

import javax.swing.*;
import java.awt.*;

import java.awt.event.*; // step 1

public class JTextAreaDemo extends JFrame //step 2
                             implements ActionListener{
  
  private JTextArea ta1 = new JTextArea(10,20);
  private JButton btn = new JButton("Add");
  private JButton btn2 = new JButton("Append");
  private JButton btn3 = new JButton("Get text in TextArea");

  public JTextAreaDemo() {

    getContentPane().setLayout(new FlowLayout());
    getContentPane().add(ta1);
    getContentPane().add(btn);
    getContentPane().add(btn2);
    getContentPane().add(btn3);
       
    btn.addActionListener(this);//step 4:
    btn2.addActionListener(this);
    btn3.addActionListener(this);
    
  } //end constructor
  
  public void actionPerformed(ActionEvent teckyong){//step 3
    
      if (teckyong.getSource() == btn){
        ta1.setText("ABC"); // Add text, overwrite the previous
      } //end if
      else if (teckyong.getSource() == btn2){
        ta1.append("ABC\n");
      }
      else if (teckyong.getSource() == btn3){
        String s = ta1.getText(); // Get what is in the TextArea
        JOptionPane.showMessageDialog(null,s);
      }
    
  } //end actionPerformed

  public static void main(String[] args) {
    JTextAreaDemo f = new JTextAreaDemo();
    f.setTitle("OOPG");
    f.setSize(300, 300);
    f.setVisible(true);

  } //end main
} //end class

ImageIcon example

 import javax.swing.*;
import java.awt.*; // layout
// Step 1
import java.awt.event.*; //ActionListener

public class TongjinFrame extends JFrame
         /*Step 2*/  implements ActionListener{
  
  private JLabel lblPic;
  private ImageIcon imgTJ, imgIvan;
  
  private JButton btnChange;
  
  public TongjinFrame(){
    
    imgTJ = new ImageIcon("tongjin.jpg");
    imgIvan = new ImageIcon("ivan.jpg");
        
    lblPic = new JLabel(imgTJ);
    
    btnChange = new JButton("Change");
    
    getContentPane().add(lblPic);
    getContentPane().add(btnChange, "South");
    
    // Step 4
    btnChange.addActionListener(this);
  }
  
  // Step 3:
  public void actionPerformed(ActionEvent ev){
    lblPic.setIcon(imgIvan);
  } //end actionPerformed
  
}//end class

GUI with ActionListener

  import javax.swing.*;
import java.awt.*;

import java.awt.event.*;

public class ScaleConverter2 extends JFrame
                   implements ActionListener{
                

  private JLabel lblValue, lblResult;
  private JButton btnCompute, btnCancel;
  private JRadioButton rbKm, rbMetre, rbCm;
  private JRadioButton rbToKm, rbToMetre, rbToCm;
  private JPanel convertFromPnl, convertToPnl, calculatePnl;
  private JTextField txtValue, txtResult;

  public ScaleConverter2() {
    initConvertFromPnl();
    initConvertToPnl();
    initCalculatePnl();

    getContentPane().setLayout(new GridLayout(3, 1));
    getContentPane().add(convertFromPnl);
    getContentPane().add(convertToPnl);
    getContentPane().add(calculatePnl);

  } //end constructor

  public void initConvertFromPnl() {
    convertFromPnl = new JPanel(new GridLayout(3, 1));
    rbKm = new JRadioButton("Km");
    rbMetre = new JRadioButton("Metre");
    rbCm = new JRadioButton("Cm");
    convertFromPnl.add(rbKm);
    convertFromPnl.add(rbMetre);
    convertFromPnl.add(rbCm);
    convertFromPnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
    
    // Set KM as the default
    rbKm.setSelected(true);
  
  }

  public void initConvertToPnl() {
    convertToPnl = new JPanel(new GridLayout(3, 1));
    rbToKm = new JRadioButton("Km");
    rbToMetre = new JRadioButton("Metre");
    rbToCm = new JRadioButton("Cm");
    convertToPnl.add(rbToKm);
    convertToPnl.add(rbToMetre);
    convertToPnl.add(rbToCm);
    convertToPnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
  
    rbToMetre.setSelected(true);
  }

  public void initCalculatePnl() {
    calculatePnl = new JPanel(new GridLayout(3, 2,5,5));
    lblValue = new JLabel("Value");
    lblResult = new JLabel("Result");
    btnCompute = new JButton("Compute");
    btnCancel = new JButton("Cancel");
    txtValue = new JTextField(10);
    txtResult = new JTextField(10);

    calculatePnl.add(lblValue);
    calculatePnl.add(txtValue);
    calculatePnl.add(lblResult);
    calculatePnl.add(txtResult);
    calculatePnl.add(btnCompute);
    calculatePnl.add(btnCancel);

    calculatePnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
  
    btnCompute.addActionListener(this);
    
  } //end init
  
  
  public void actionPerformed(ActionEvent ev){
    if (ev.getSource() == btnCompute){
      String input = txtValue.getText();//retrieve from textfield
      double value = Double.parseDouble(input);
      double result = 0;
      
      // if the user wants to convert km to m
      if (rbKm.isSelected() && 
          rbToMetre.isSelected()){
          result = value*1000;
      }
      
      txtResult.setText(String.valueOf(result));
    }
  } //end actionPerformed

  public static void main(String args[]) {
    ScaleConverter2 f = new ScaleConverter2();
    f.setSize(400, 400);
    f.setVisible(true);
    f.setTitle("Scale Converter");
  } //end main

} //end class

GUI Solution Only

import javax.swing.*;
import java.awt.*;

public class ScaleConverter
    extends JFrame {

  private JLabel lblValue, lblResult;
  private JButton btnCompute, btnCancel;
  private JRadioButton rbKm, rbMetre, rbCm;
  private JRadioButton rbToKm, rbToMetre, rbToCm;
  private JPanel convertFromPnl, convertToPnl, calculatePnl;
  private JTextField txtValue, txtResult;

  public ScaleConverter() {
    initConvertFromPnl();
    initConvertToPnl();
    initCalculatePnl();
    
    getContentPane().setLayout(new GridLayout(3, 1));
    getContentPane().add(convertFromPnl);
    getContentPane().add(convertToPnl);
    getContentPane().add(calculatePnl);
    
  } //end constructor

  public void initConvertFromPnl() {
    convertFromPnl = new JPanel(new GridLayout(3, 1));
    rbKm = new JRadioButton("Km");
    rbMetre = new JRadioButton("Metre");
    rbCm = new JRadioButton("Cm");
    convertFromPnl.add(rbKm);
    convertFromPnl.add(rbMetre);
    convertFromPnl.add(rbCm);
    convertFromPnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
  }

  public void initConvertToPnl() {
    convertToPnl = new JPanel(new GridLayout(3, 1));
    rbToKm = new JRadioButton("Km");
    rbToMetre = new JRadioButton("Metre");
    rbToCm = new JRadioButton("Cm");
    convertToPnl.add(rbToKm);
    convertToPnl.add(rbToMetre);
    convertToPnl.add(rbToCm);
    convertToPnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
  }

  public void initCalculatePnl() {
    calculatePnl = new JPanel(new GridLayout(3, 2,5,5));
    lblValue = new JLabel("Value");
    lblResult = new JLabel("Result");
    btnCompute = new JButton("Compute");
    btnCancel = new JButton("Cancel");
    txtValue = new JTextField(10);
    txtResult = new JTextField(10);

    calculatePnl.add(lblValue);
    calculatePnl.add(txtValue);
    calculatePnl.add(lblResult);
    calculatePnl.add(txtResult);
    calculatePnl.add(btnCompute);
    calculatePnl.add(btnCancel);
  
    calculatePnl.setBorder(BorderFactory.createTitledBorder("Convert from"));
  } //end init

  public static void main(String args[]) {
    ScaleConverter f = new ScaleConverter();
    f.setSize(400, 400);
    f.setVisible(true);
    f.setTitle("Scale Converter");
  } //end main

} //end class

Setting Border

convertFromPnl.setBorder(BorderFactory.createTitledBorder("Convert From"));

Do this GUI

Demo02 : Event Handling

import javax.swing.*;
import java.awt.*; 
import java.awt.event.*; 

public class Demo02 extends JFrame
        implements ActionListener{

  private JButton btn1, btn2;
  private JPanel northPanel;

  public Demo02(){
    btn1 = new JButton("Button 1");
    btn2 = new JButton("Button 2");
    northPanel = new JPanel();
    northPanel.add(btn1);
    northPanel.add(btn2);
    getContentPane().add(northPanel, 
                         BorderLayout.NORTH);
    // Step 4: 
    btn1.addActionListener(this);
    btn2.addActionListener(this);
  }//end constructor


  // Step 3: add this method
  public void actionPerformed(ActionEvent ev){
    if (ev.getSource() == btn1)
        JOptionPane.showMessageDialog(null,
             "Hi,you clicked button 1");
    else if (ev.getSource() == btn2){
      JOptionPane.showMessageDialog(null,
             "Hi,you clicked button 2");
    }
  }//end actionPerformed


}//end class

Demo 01 : Event Handling

import javax.swing.*;
import java.awt.*; // Layout
// Step 1
import java.awt.event.*; // Event

public class Demo01 extends JFrame
  /*Step 2*/     implements ActionListener{
  
  private JButton btn1;
  private JPanel northPanel;
  
  public Demo01(){
    btn1 = new JButton("Button 1");
    northPanel = new JPanel();
    northPanel.add(btn1);
    getContentPane().add(northPanel, 
                         BorderLayout.NORTH);
    // Step 4: 
    btn1.addActionListener(this);
  }//end constructor
  
  
  // Step 3: add this method
  public void actionPerformed(ActionEvent ev){
    JOptionPane.showMessageDialog(null,
             "Hi,you clicked button 1");
  }//end actionPerformed

  
}//end class

Practical 08 Question 2

 public class TestTourBookingFrame {

  public static void main(String[] args) {
    
    //(a)Create an instance of the 
    //TourBookingFrame named f.
    
    TourBookingFrame f = new TourBookingFrame();
    //(b)Set the title of f to be “Tour Booking Frame”.
    f.setTitle("Tour Booking Frame");
    //(c)Set the size of f to be 500 by 250.
    f.setSize(500,250);
    //(d)Set f to be visible.
    f.setVisible(true);

    f.show();
  } //end main
  
}//end class

Practical 08 Question 1

//(a)Import all relevant packages
import javax.swing.*;
import java.awt.*; // Layout

/*(b)Write the codes to specify 
 TourBookingFrame as the subclass of JFrame.*/
public class TourBookingFrame extends JFrame{
 
  private ButtonGroup buttongroup;
/*(c)Declare all the components in the JFrame
  */
 private JLabel welcomeLbl;
 private JTextArea detailsTxt;
 private JRadioButton memberBtn, nonMemberBtn;
 private JButton submitBtn, resetBtn;
 // (d)Declare all the JPanels
 private JPanel northPanel, centerPanel, southPanel;
 
 public TourBookingFrame(){
   //(e)Create northPanel and welcomeLbl. 
   // Add welcomeLbl to northPanel
   northPanel = new JPanel();
   welcomeLbl = new JLabel("Welcome to Tour Booking"
                          + " System, enter your booking"
                          + " details below");
  northPanel.add(welcomeLbl);
  
  // f) Create centerPanel and detailsTxt.
  // Add detailsTxt to centerPanel. 
  // detailsTxt should be 10 rows 40 columns wide. 
  centerPanel = new JPanel();
  detailsTxt = new JTextArea(10,40);
  centerPanel.add(detailsTxt);
  
  // (g) Create southPanel & component(s) in southPanel.  
  // Add the component(s) to southPanel.
  southPanel = new JPanel();
  memberBtn = new JRadioButton("Member");
  nonMemberBtn = new JRadioButton("Non-member");
  submitBtn = new JButton("Submit");
  resetBtn = new JButton("Reset");
  southPanel.add(memberBtn);
  southPanel.add(nonMemberBtn);
  southPanel.add(submitBtn);
  southPanel.add(resetBtn);
  
  buttongroup = new ButtonGroup();
  buttongroup.add(memberBtn);
  buttongroup.add(nonMemberBtn);
  
//(h)Which Layout Manager would the JFrame be using?
//  Add all the JPanels to the respective areas of 
//the content Pane of the JFrame.
  getContentPane().add(northPanel, BorderLayout.NORTH);
  getContentPane().add(centerPanel, BorderLayout.CENTER);
  getContentPane().add(southPanel, BorderLayout.SOUTH);
  
} //end constructor
  
}//end class

Assignment Starter Kit

import javax.swing.*; // For JFrame, JButton etc
import java.awt.*; // For layout 

public class QuizFrame extends JFrame {

    private JLabel lblCategory;

    private JPanel panelButtons;
    private JButton btnPrev, btnNext;

    public QuizFrame() {
        makeNorth();
        makeCenter();
        makeSouth();

    } //end constructor

    public void makeNorth() {
        lblCategory = new JLabel("IT Quiz");
        getContentPane().add(lblCategory, "North");
    }

    public void makeCenter() {

    }

    public void makeSouth() {
        // Step 1: Create Panel and components
        panelButtons = new JPanel();
        btnPrev = new JButton("Prev");
        btnNext = new JButton("Next");
        // Step 2: Add components to panel
        panelButtons.add(btnPrev);
        panelButtons.add(btnNext);

        // Step 3:
        getContentPane().add(panelButtons, "South");

    }


} //end class

import javax.swing.*;
import java.awt.*; // Necessary for layout

public class DifferentLayouts extends JFrame {

    private JButton b1, b2, b3, b4, b5, b6;


    public DifferentLayouts() {
        
        getContentPane().setLayout(new GridLayout(3,2));

        b1 = new JButton("b1");
        b2 = new JButton("b2");
        b3 = new JButton("b3");
        b4 = new JButton("b4");
        b5 = new JButton("b5");
        b6 = new JButton("b6");
        
        getContentPane().add(b1);
        getContentPane().add(b2);
        getContentPane().add(b3);
        getContentPane().add(b4);
        getContentPane().add(b5);
        getContentPane().add(b6);
      

    } //end constructor

    public static void main(String[] args) {
        DifferentLayouts f;
        f = new DifferentLayouts();
        f.setSize(300, 300);
        f.setVisible(true);
    } //end main
} //end class

import javax.swing.*;

// In this example, no layout is specified
// BorderLayout applies becos JFrame uses BorderLayout
// by default
// Therefore, components must all have
// a direction specified

public class MyThirdGUI extends JFrame{

    // Step 1: Declare the components
    private JButton tongjin;
    private JTextField ivan;

    public MyThirdGUI(){             
        // Step 2: Create the component
        tongjin = new JButton("Click me");
        ivan = new JTextField(10);

        // Step 3: Add the component to the container
        getContentPane().add(tongjin,"South");
        getContentPane().add(ivan);
    }



    public static void main(String args[]){
       MyThirdGUI barnet = new MyThirdGUI();

       barnet.setSize(100,200);
       barnet.setVisible(true);

    } //end main

}//end class

import javax.swing.*;

public class MySecondGUI extends JFrame{
    
    // Step 1: Declare the componentw
    private JButton tongjin;
    
    public MySecondGUI(){
        // Step 2: Create the component
        tongjin = new JButton("Click me");
        
        // Step 3: Add the component to the container
        getContentPane().add(tongjin);
    }
    
    
    
    public static void main(String args[]){
       MySecondGUI barnet = new MySecondGUI();
       
       barnet.setSize(100,200);
       barnet.setVisible(true);
       
    } //end main
    
}//end class

// Step 1: Import the package classes
import javax.swing.*;

public class MyFirstGUI extends JFrame/*Step2*/{
   
    public static void main(String args[]){
        
        // Step 3: Instantiate an instance
        MyFirstGUI yonghui= new MyFirstGUI();
        
        // Step 4: Set the properties
        yonghui.setSize(300,400);
        yonghui.setVisible(true);
       
    }//end main
    
    
}//end class

Practical 6 Additional Q1

public class Entry { private String title, name, address; // Purpose of a constructor: // Initialise instance variables public Entry(String title, String name, String address){ this.title = title; this.name = name; this.address = address; } //end constructor public void setTitle(String title){ this.title = title; } public void setName(String name){ this.name = name; } public void setAddress(String address){ this.address = address; } public void printEntryDetails(){ System.out.println("To:" + title + " " + name); System.out.println("Address:" + address + "\n"); } //end printEntryDetails }//end class

public class AddressBook { public static void main(String[] args) { Entry entry1, entry2, entry3; entry1 = new Entry("Mr.", "Chris Howard Shin", "1 Elm Street S(123456)"); entry2 = new Entry("Miss", "Mary Lim", "Blk 222 Hougang Ave 4 S(530222)"); entry3 = new Entry("Mr.", "John Tang", "Blk 333 Hougang Ave 1 S(530333)"); entry1.printEntryDetails(); entry2.printEntryDetails(); entry3.printEntryDetails(); entry1.setName("TCS"); entry2.setTitle("Mrs"); entry3.setAddress("Blk 333 Ang Mo Kio Ave 1 S(530333)"); entry1.printEntryDetails(); entry2.printEntryDetails(); entry3.printEntryDetails(); } //end main }//end class

Solution for Mock Test (Available only until 10 Nov 2006)

import javax.swing.*;

public class VendingMachine {

  public static int readChoice() {
    String inputString;
    int choice;
    do {
      inputString = JOptionPane.showInputDialog(null,
                                                "Enter your choice of drink:\n"
                                                + "1. Coke (60 cents)\n"
                                                + "2. Pepsi (60 cents)\n"
                                                + "3. Soya Bean (50 cents)\n"
                                                + "4. Green Tea (70 cents)\n"
                                                + "5. Ice Coffee (80 cents)\n",
                                                "SP Vendimatic Vending Machine",
                                                JOptionPane.QUESTION_MESSAGE);
      choice = Integer.parseInt(inputString);

      if (choice < 1 || choice > 5) {
        JOptionPane.showMessageDialog(null,
                                      "Invalid input ! Please enter in the range from 1 to 5.",
                                      "Error",
                                      JOptionPane.ERROR_MESSAGE);
      }
    } while (choice < 1 || choice > 5);

    return choice;
  }

  public static int computeAndDisplayPrice(int choice) {
    int price = 0;
    switch (choice) {
      case 1:
      case 2:
        price = 60;
        break;
      case 3:
        price = 50;
        break;
      case 4:
        price = 70;
        break;
      case 5:
        price = 80;
    }
    JOptionPane.showMessageDialog(null,
                                  "Price is " + price + " cents");
    return price;
  }

  public static int readPayment(int price) {
    String inputString;
    int payment;
    do {
      inputString = JOptionPane.showInputDialog(null,
                                                "Please enter your payment ("
                                                + price + " - 100 cents):\n",
                                                "SP Vendimatic Vending Machine",
                                                JOptionPane.QUESTION_MESSAGE);
      payment = Integer.parseInt(inputString);

      if (payment < price) {
        JOptionPane.showMessageDialog(null,
                                      "Invalid input ! Please enter a minimum payment of " +
                                      price + " cents.",
                                      "Error",
                                      JOptionPane.ERROR_MESSAGE);
      } else if (payment > 100) {
        JOptionPane.showMessageDialog(null,
                                      "Invalid input ! Please do not enter more than 100 cents.",
                                      "Error",
                                      JOptionPane.ERROR_MESSAGE);
      }
    } while (payment < price || payment > 100);

    return payment;
  }

  public static int computeAndDisplayChange(int payment, int price) {
    int change;
    change = payment - price;
    JOptionPane.showMessageDialog(null, "Change is " + change + " cents.");
    return change;
  }

  public static void dispenseChange(int change) {
    int num50cents, num20cents, num10cents;
    int balance;

    num50cents = change / 50;
    balance = change % 50;

    num20cents = balance / 20;
    balance = balance % 20;

    num10cents = balance / 10;
    String s = "Dispensing...\n"
                                   + num50cents + " x 50c coin\n"
                                   + num20cents + " x 20c coin\n"
                                   + num10cents + " x 10c coin";

    JOptionPane.showMessageDialog(null, s );

  }

  public static void main(String[] args) {
    int choice;
    int price;
    int payment;
    int change;

    String inputString;

    char cont;

    do {
      choice = readChoice();
      price = computeAndDisplayPrice(choice);
      payment = readPayment(price);
      change = computeAndDisplayChange(payment, price);

      if (change > 0) {
        dispenseChange(change);
      }

      do {
        inputString = JOptionPane.showInputDialog(null,
                                                  "Do you want another drink (Y/N)?");
        cont = inputString.charAt(0);

        if (! (cont == 'Y' || cont == 'N' || cont == 'y' || cont == 'n')) {
          JOptionPane.showMessageDialog(null,
                                        "Invalid input ! Please enter Y or N.",
                                        "Error",
                                        JOptionPane.ERROR_MESSAGE);
        }
      }
      while (! (cont == 'Y' || cont == 'N' || cont == 'y' || cont == 'n'));

    }
    while (cont == 'Y' || cont == 'y');
    JOptionPane.showMessageDialog(null,
                                  "VendingMachine class program terminated.");

  } //end main

} //end class