ComponentsTypes of ComponentsButtonA Button listenerLabel constructorsLabel methodsScrollbar constructorsScrollbarsScrollbar methodsA Scrollbar listenerCheckbox constructorsCheckbox methodsA Checkbox listenerCheckboxGroup methodsA CheckboxGroup listenerChoice constructorChoice methodsA Choice listenerList constructorsList methods IList methods IIA List listenerTextComponentTextField constructorsTextField methodsTextArea constructorsTextComponent listenersCanvasThe EndComponentsTypes of Components•Button•Canvas•Checkbox•Choice•Label•List•Scrollbar•TextComponent–TextArea–TextFieldButton•Button() constructs a Button with no text•Button(String) constructs a Button with the specified text•void addActionListener(ActionListener)•void removeActionListener(ActionListener)•String getLabel()•void setLabel(String)•String actionEvent.getActionCommand()A Button listener button.addActionListener (new MyButtonListener ()); class MyButtonListener implements ActionListener { public void actionPerformed (ActionEvent event) { showStatus ("Button clicked."); }}Label constructors•Label() constructs a Label with no text•Label(String) constructs a Label with the specified text•Label(String, int) constructs a label with the specified text and alignment:–Label.LEFT–Label.RIGHT–Label.CENTERLabel methods•String getText()•void setText(String)•int getAlignment()•void setAlignment(int)Scrollbar constructors•Scrollbar() creates a vertical Scrollbar•Scrollbar(int orientation)–Scrollbar.HORIZONTAL or Scrollbar.VERTICAL•Scrollbar(int orientation, int initialValue, int bubbleSize, int minimum, int maximum)–bubbleSize: size of the bubble (sometimes called elevator)–min value of Scrollbar = minimum–max value of Scrollbar = maximum - bubbleSize•(value of scrollbar is given by left or top edge of bubble)–initialValue: the initial position setting of the bubbleScrollbarsbubbleSizeminimummaximummaximum — bubbleSizeThe units for bubbleSize are the same as those for minimum and maximumScrollbar methods•void addAdjustmentListener(AdjustmentListener)•void removeAdjustmentListener(AdjustmentListener)•int getMinimum()•void setMinimum(int)•int getMaximum()•void setMaximum(int)•int getValue()•void setValue(int)A Scrollbar listenerscrollbar.addAdjustmentListener(new MyScrollbarListener ()); class MyScrollbarListener implements AdjustmentListener { public void adjustmentValueChanged (AdjustmentEvent event) { showStatus ("Scrollbar: " + scrollbar.getValue ()); }};Checkbox constructors•Checkbox()•Checkbox(String)•Checkbox(String, boolean)•Checkbox(String, boolean, CheckboxGroup)•Checkbox(String, CheckboxGroup, boolean)Checkbox methods•void addItemListener(ItemListener)•void removeItemListener(ItemListener)•CheckboxGroup getCheckboxGroup()•void setCheckboxGroup(CheckboxGroup)•String getLabel()•void setLabel(String)A Checkbox listener checkbox.addItemListener (new MyCheckboxListener ()); class MyCheckboxListener implements ItemListener { public void itemStateChanged (ItemEvent event) { showStatus ("Checkbox status is now " + (event.getStateChange () == ItemEvent.SELECTED)); }};CheckboxGroup methods•Checkbox getSelectedCheckbox()–Suggested use:myCG.getSelectedCheckbox().getLabel()•void setSelectedCheckbox(Checkbox)A CheckboxGroup listener•No such thing—listen to individual Checkboxes checkbox1.addItemListener (myCheckboxGroupListener); checkbox2.addItemListener (myCheckboxGroupListener);class MyCheckboxGroupListener implements ItemListener { public void itemStateChanged (ItemEvent event) { Checkbox d = checkboxGroup.getSelectedCheckbox (); showStatus ("CheckboxGroup: " + d.getLabel ()); }}Choice constructor•Choice()•After constructing a Choice, use add(String) to add items to itChoice methods•addItemListener(ItemListener)•removeItemListener(ItemListener)•void add (String)•void remove(String)•void removeAll()•String getSelectedItem()•void select(String)A Choice listener choice.addItemListener (new MyChoiceListener ()); class MyChoiceListener implements ItemListener { public void itemStateChanged (ItemEvent event) { showStatus ("Choice: " + choice.getSelectedItem ()); }};List constructors•List() constructs an empty list•List(int)–int: the number of items visible (a scrollbar is automatically added if needed)•List(int, boolean)–boolean: true if multiple selection is allowedList methods I•void addItemListener(ItemListener)•void removeItemListener(ItemListener)•void add(String)•void remove(String)•void removeAll()List methods II•String getSelectedItem()•String[] getSelectedItems()•int getSelectedIndex()•int[] getSelectedIndexes()•void select(int) // can only select by index–There are other methods for adding, removing, etc. by indexA List listener list.addItemListener (new MyListListener ()); class MyListListener implements ItemListener { public void itemStateChanged (ItemEvent event) { showStatus ("List: " + list.getSelectedItem ()); }};TextComponent•No constructors–Instead, construct a TextField or TextArea•void addTextListener(TextListener)•void removeTextListener(TextListener)•String getText()•void setText(String)•boolean isEditable()•void setEditable(boolean)TextField constructors•TextField()•TextField(int)–int: the approximate desired number of columns•TextField(String)–String: the initial text in the TextField•TextField(String, int)TextField methods•void addActionListener(ActionListener)•void removeActionListener(ActionListener)•The ActionListener for a TextField responds only when the Enter key is pressedTextArea constructors•TextArea()•TextArea(int rows, int columns)•TextArea(int rows, int columns, int scroll)–TextArea.SCROLLBARS_VERTICAL_ONLY–TextArea.SCROLLBARS_HORIZONTAL_ONLY–TextArea.SCROLLBARS_BOTH–TextArea.SCROLLBARS_NONE•TextArea(String)•TextArea(String, int rows, int columns)TextComponent listeners textField.addActionListener (new MyTextFieldListeners ()); textField.addTextListener (new MyTextFieldListeners ()); class MyTextFieldListeners implements ActionListener,TextListener { public void actionPerformed (ActionEvent event) { showStatus ("TextField (ActionListener): " + textField.getText ()); } public void
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