Download Class 1 ~ Chapter 1

Class 20
Class 20 Objectives

Use JCheckbox, JRadioButton, and a
JComboBox in a UID
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
JCheckbox
– A boolean GUI component that is
either selected or not selected
 JRadioButton
– A group of usually circular gui
components that allow for only
one in the group to be selected
 JComboBox
– A drop-down list from which the
user can make a selection (in
AWT called Choice list)
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Class JCheckBox


is a JComponent
creates a single box that can be
selected or not selected
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Write a windowed application that will display the
following gui. After the user makes the selections, you
program will tell the user how many classes they chose.
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// Creating Checkbox buttons.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CheckBoxFrame extends JFrame
{ private String classes[] = {“Swim”,
“Dance”,”Tennis”};
private JTextField nameField;
private JCheckBox choices[];
private JLabel labelField;
private JLabel label1;
private JButton doneButton;
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public CheckBoxFrame()
{ super( "JCheckBox Test" );
Container theWindow = getContentPane();
theWindow.setLayout(new FlowLayout());
doneButton = new JButton(“Done”);
nameField = new JTextField( 20);
label1 = new JLabel(“enter your name”);
labelField = new JLabel(“Select the classes you“ +
“want to take then click the \”Done\” button ”);
nameField.setFont( new Font( "TimesRoman",
Font.PLAIN, 14 ) );
theWindow.add(label1);
theWindow.add( nameField);
theWindow.add(labelField);
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choices = new JCheckBox[classes.length];
for (int i = 0; i < classes.length; i++)
{ choices[i] = new JCheckBox(classes[i]);
theWindow.add(choices[i]); }
theWindow.add(doneButton);
doneButton.addActionListener(new ActionListener()
{ public void actionPerformed(ActionEvent ev)
{ buttonClicked(ev) };
} );
setSize(350,200);
setVisible(true);
} // end of constructor
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public void buttonClicked( ActionEvent event )
{
int classCount =0;
for (int i=0; i< classes.length; i++)
if ( choices[i].isSelected() ==true)
++classCount;
JOptionPane.showMessageDialog( null,
nameField.getText() + “ \n You have” +
“ decided to take “ + classCount + “
class(es)”);
}
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public static void main(String a[])
{ CheckBoxFrame cf = new CheckBoxFrame();
cf.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE);
}
} // end of class
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Add JRadioButtons to the previous application to
allow user to choose MWF or Tues./Thurs classes.
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// Creating Radio buttons.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class RadioButtonTest extends JFrame
{ private String classes[] = {“Swim”,
“Dance”,”Tennis”};
private JTextField nameField;
private JCheckBox choices[];
private JLabel labelField1,labelField2;
private JLabel label1;
private JButton doneButton;
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// new gui components
private JRadioButton dayChoice1;
private JRadioButton dayChoice2;
private ButtonGroup radioGroup;
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public RadioButtonTest()
{ super( “RadioButton Test" );
Container theWindow = getContentPane();
windowFrame.setLayout(new FlowLayout());
doneButton = new JButton(“Done”);
nameField = new JTextField( 20);
label1 = new JLabel(“Enter your name”);
labelField1 = new JLabel(“Select the classes you “ +
“want to take ”);
labelField2 = new JLabel(“and the days, then click” +
“the \”Done\” button”);
nameField.setFont( new Font( "TimesRoman",
Font.PLAIN, 14 ) );
theWindow.add(label1);
theWindow.add( nameField);
theWindow.add(labelField1);
theWindow.add(labelField2);
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// create logical relationship between JRadioButtons
radioGroup = new ButtonGroup();
radioGroup.add( dayChoice1);
radioGroup.add( dayChoice2 );
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choices = new JCheckBox[classes.length];
for (int i = 0; i < classes.length; i++)
{ choices[i] = new JCheckBox(classes[i]);
theWindow.add(choices[i]); }
dayChoice1 = new JRadioButton(“MWF”,true);
dayChoice2= new JRadioButton(“TTH”,false);
theWindow.add(dayChoice1);
theWindow.add(dayChoice2);
theWindow.add(doneButton);
doneButton.addActionListener(new ActionListener()
{ public void actionPerformed(ActionEvent ev)
{ buttonClicked(ev) };
} );
setSize(350,200);
setVisible(true);
} // end of constructor
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public void buttonClicked( ActionEvent event )
{
int classCount =0;
String daySelection;
if (dayChoice1.isSelected() == true)
daySelection = “MWF”;
else
daySelection = “TTH”;
for (int i=0; i< classes.length; i++)
if ( choices[i].isSelected() ==true)
++classCount;
JOptionPane.showMessageDialog( null,
nameField.getText() + “ \n You have” +
“ decided to take “ + classCount + “ class(es)” +
“on ” + daySelection);
}
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public static void main(String a[])
{ RadioButtonTest rt = new RadioButtonTest();
rt.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE);
}
}
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Use a JComboBox for making
a selection
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// ComboBoxTest.java
// Using a JComboBox to select an image to
display.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ComboBoxFrame extends JFrame
{ private JComboBox choicesJComboBox;
private JLabel label;
private String names[] =
{ “Aruba”, “Cancun”, “Dallas”,
“Puerto Vallarta”, “San Juan” };
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private double costs[] = {1800.00, 1300.00,
0.0, 1345.00, 1500.00};
public ComboBoxFrame()
{ super( "Testing JComboBox" );
Container windowPane = getContentPane();
windowPane.setLayout( new FlowLayout() );
choicesJComboBox = new JComboBox( names );
choicesJComboBox.setMaximumRowCount( 3 );
windowPane.add( choicesJComboBox );
label = new JLabel(“Make a selection ” +
“for your 7 day spring break trip” );
add( label );
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choicesJComboBox.addItemListener( new ItemListener()
{ public void itemStateChanged(ItemEvent e)
{ whatSelection(e); }
);
setSize(350,200);
setVisible(true);
} // end of constructor
private void whatSelection( ItemEvent event )
{ if (event.getStateChange() == ItemEvent.SELECTED)
{ int selection =
choicesJComboBox.getSelectedIndex();
JOptionPane.showMessageDialog(null,
“You selected” + names[selection] + “for” +
“ a total cost of “ + costs[selection]);
}
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public static void main(String a[])
{ ComboBoxFrame cf = new ComboBoxFrame();
cf.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE);
}
}
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Conclusion of class 20
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