5.2.6 Other GUI Components

In this subsection we list the constructors and main methods for GUI components that we have not treated yet. Here, we shall exemplify the components to their bare minimum, but in applets we shall give complete examples. A complete and detailed list of constructors and methods for all GUI components can be found in the Java API documentation that is available on the Web.

The Checkbox Class
The CheckboxGroup Class
The Choice Class
The List Class

The `Checkbox` Class

Applet

Relevant Java Code

public class Checklist extends Applet {

  public void init() {
    //  define checkboxes and place them vertically
    setLayout(new GridLayout(4, 1));
    add(new Checkbox("cash"));
    add(new Checkbox("credit card"));
    add(new Checkbox("passport"));
    add(new Checkbox("ticket(s)"));
  }
}

Constructors and Methods

*Constructors*	*Meaning*
`Checkbox()`	creates a checkbox with no label and no checkbox group
`Checkbox(String label)`	creates a checkbox with the specified label but with no checkbox group
`Checkbox(String label, CheckboxGroup group, boolean state)`	creates a checkbox with the specified label, the specified checkbox group, and the specified state
*Methods*	*Meaning*
`getCheckboxGroup()`	returns the checkbox group associated with the given checkbox
`getLabel()`	returns the label of the checkbox
`getState()`	returns the checkbox state: selected (`true`) or unselected (`false`)
`setCheckboxGroup(CheckboxGroup group)`	associate the checkbox with the given checkbox group
`setLabel(String label)`	changes the label of the checkbox
`setState(boolean state)`	changes the checkbox state: selected (`true`) or unselected (`false`)

The `CheckboxGroup` Class

Applet

Relevant Java Code

public class Fontstyles extends Applet {

  public void init() {
    //  create checkbox group
    Checkboxgroup style = new Checkboxgroup();
    //  define checkboxes and
    //  place them vertically in checkbox group
    setLayout(new GridLayout(4, 1));
    add(new Checkbox("Plain", style, true));
    add(new Checkbox("Bold", style, false));
    add(new Checkbox("Italic", style, false));
    add(new Checkbox("Bold Italic", style, false));
  }
}

Constructors and Methods

*Constructor*	*Meaning*
`CheckboxGroup()`	creates a checkbox group
*Methods*	*Meaning*
`getCurrent()`	returns the current choice of checkbox in the checkbox group
`setCurrent(Checkbox current)`	sets the current choice to the specified checkbox

The `Choice` Class

Applet

Relevant Java Code

public class Fontsize extends Applet {

  public void init() {
    //  create choice component
    Choice fontsize = new Choice();
    //  add items
    fontsize.addItem("10");
    fontsize.addItem("11");
    fontsize.addItem("12");
    fontsize.addItem("18");
    fontsize.addItem("20");
    fontsize.addItem("24");
    fontsize.addItem("36");
    //  add component to applet
    add(fontsize);
  }
}

Constructors and Methods

*Constructor*	*Meaning*
`Choice()`	creates a new choice component
*Methods*	*Meaning*
`addItem(String item)`	Add an item with the specified label
`countItems()`	returns the number of items
`getItem(int index)`	returns the item with the specified index
`getSelectedIndex()`	returns the index of the currently selected item
`getSelectedItem()`	returns the label of the currently selected item
`select(int index)`	select the item at the specified index
`select(String label)`	select the item with the specified label.

The `List` Class

Applet

Relevant Java Code

public class NameList extends Applet {

  public void init() {
    //  create choice component
    List names = new List(3, true);
    //  add items to list of names
    names.addItem("Alfred");
    names.addItem("Benjamin");
    names.addItem("Charles");
    names.addItem("David");
    names.addItem("Edward");
    //  add component to applet
    add(names);
  }
}

Constructors and Methods

*Constructors*	*Meaning*
`List()`	creates an empty scrolling list with no visible rows or multiple selections.
`List(int numberOfRows, boolean multipleSelections)`	creates a scrolling list with the specified number of visible rows and a boolean stating whether multiple selections are allowed (`true`) or forbidden (`false`)
*Methods*	*Meaning*
`addItem(String item)`	Add an item with the specified label
`addItem(String item, int index)`	Add an item with the specified label at the given position
`clear()`	clears the list
`countItems()`	returns the number of items
`delItem(int index)`	deletes the item at the given position
`delItems(int start, int end)`	deletes list items from start to end
`deselect(int index)`	deselects the item at the given position
`getItem(int index)`	returns the item at the given position
`getRows()`	returns the number of visible rows in the list.
`getSelectedIndex()`	returns the index of the currently selected item
`getSelectedIndexes()`	returns an array of indices of currently selected items
`getSelectedItem()`	returns the label of the currently selected item
`getSelectedItems()`	returns an array of labels of currently selected items
`replaceItem(String item, int index)`	replace the item at the given position
`select(int index)`	selects the item at the given position
`select(String item)`	selects the specified item

5.2.6 Other GUI Components

The Checkbox Class

The CheckboxGroup Class

The Choice Class

The List Class

The `Checkbox` Class

The `CheckboxGroup` Class

The `Choice` Class

The `List` Class