Download - AWT-part2
-
7/28/2019 AWT-part2
1/157
-
7/28/2019 AWT-part2
2/157
Control Fundamentals
Labels
Using Buttons Applying Check Boxes
CheckBox Group
Choice Controls
Using Lists
Managing Scroll Bars
Using a Text Field
Using a TextArea
Understanding Layout Managers
, Menu Bars and Menus
Dialog Boxes
FileDialog
Handling Events by Extending AWT Components.
TOPICS
-
7/28/2019 AWT-part2
3/157
The AWT supports the following types of controls:
Control Fundamentals
-
7/28/2019 AWT-part2
4/157
To add a control to a window :
1. first create an instance of the desired control
2. then add it to a window by calling add( ) , which
is defined by Container.
Adding and Removing Controls
Component add(Component compObj)
compObjAn instance of the control that you want to add
A reference to compObj is returned.
-
7/28/2019 AWT-part2
5/157
To remove a control , call remove( ). This method is
also defined by Container
Adding and Removing Controls
void remove(Component obj)
compObjA reference to the control that you want to remove
You can remove all controls by calling removeAll( )
-
7/28/2019 AWT-part2
6/157
In general, your program simply implements the
appropriate interface and then registers an event listener
for each control that you need to monitor.
Responding to Controls
HeadlessException
Generated by all constructors of the controls
Thrown when code that is dependent on a keyboard,
display, or mouse is called in an environment that does
not support a keyboard, display, or mouse.
Added by java 1.4
-
7/28/2019 AWT-part2
7/157
A label is an object of type Label, and it contains a
string, which it displays. Label defines the followingconstructors:
Labels
1. Label( )
2. Label(String str)
3. Label(String str, int how)
1. The first version creates a blank label.
2. The second version creates a label that contains the
string specified by str.(left-justified.)
3. The third version creates a label that contains the string
specified by strusing the alignment specified by how
-
7/28/2019 AWT-part2
8/157
The value ofhow must be one of these three constants:1. Label.LEFT,2. Label.RIGHT,3. Label.CENTER.
Labels
void setText(String str) set or change the text in a label
StringgetText( ) obtain the current label
void setAlignment(int how) set the alignment of the string
intgetAlignment( ) obtain the current alignment
how must be one of the alignment constants
shown above
Methods :
-
7/28/2019 AWT-part2
9/157
The following example creates three labels and adds them to an
applet:
-
7/28/2019 AWT-part2
10/157
Following is the window created by the LabelDemo applet
-
7/28/2019 AWT-part2
11/157
Using Buttons
The most widely used control is the push button.
A push button is a component that contains a label and that
generates an event when it is pressed. Push buttons are objects
of type Button.
Constructors:
1. Button( )creates an empty button
2. Button(String str) creates a button that contains stras a label.
Methods :1. void setLabel(String str) set the label
2. String getLabel( ) retrieve the label
-
7/28/2019 AWT-part2
12/157
Handling Buttons
Each time a button is pressed, an Action Event is generated.
Each listener implements theActionListenerinterface.
This interface defines the actionPerformed( ) method, which
is called when an event occurs.
An ActionEvent object is supplied as the argument to this
method.
The label is obtained by calling getActionCommand() on
ActionEvent Object
(ActionEvent contains both a reference to the button that generated the
event and a reference to the string that is the label of the button)
-
7/28/2019 AWT-part2
13/157
Handling Buttons
Here is an example that creates three buttons labeled Yes, No, and Undecided.
Each time one is pressed, a message is displayed that reports which button has been
pressed.
-
7/28/2019 AWT-part2
14/157
-
7/28/2019 AWT-part2
15/157
-
7/28/2019 AWT-part2
16/157
Sample output
-
7/28/2019 AWT-part2
17/157
Handling Buttons
You can also determine which button has been pressed, by
comparing the object obtained from thegetSource( ) method
To do this, you must keep a list of the objects when they are added.
-
7/28/2019 AWT-part2
18/157
-
7/28/2019 AWT-part2
19/157
Handling Buttons
-
7/28/2019 AWT-part2
20/157
Applying Check Boxes
-
7/28/2019 AWT-part2
21/157
Applying Check Boxes
A check box is a control that is used to turn an option on or off
There is a label associated with each checkbox that describes
what option the box represents
Check boxes are objects of the Checkbox class.
Constructors:
1. Checkbox( )
2. Checkbox(String str)
3. Checkbox(String str, boolean on)
4. Checkbox(String str, boolean on, CheckboxGroup cbGroup)
5. Checkbox(String str, CheckboxGroup cbGroup, boolean on)
-
7/28/2019 AWT-part2
22/157
Applying Check Boxes
1. The first form creates a check box whose label is initially
blank. The state of the check box is unchecked2. The second form creates a check box whose label is
specified by str. The state of the check box is unchecked
3. The third form allows you to set the initial state of the
check box.
4. The fourth and fifth forms create a check box whose label
is specified by str and whose group is specified by
cbGroup. If this check box is not part of a group, then
cbGroup must be null.
-
7/28/2019 AWT-part2
23/157
Applying Check Boxes
Methods :
1. booleangetState( ) retrieve the current state of a
check box
2. void setState(boolean on) To set its state
3. StringgetLabel( ) obtain the current label
associated with a check box
4. void setLabel(String str) To set the label
ifon is true, the box is checked. If it is false, the box is
cleared.
-
7/28/2019 AWT-part2
24/157
Handling Check Boxes
Each time a check box is selected or deselected, an
item eventis generated
Your program must implement ItemListenerInterface
This interface defines the itemStateChanged( ) method
An ItemEvent object is supplied as the argument to this
method.
An ItemEvent object contains information about the
event
-
7/28/2019 AWT-part2
25/157
Handling Check Boxes
The following program creates four check boxes. The initial
state of the first box is checked. The status of each check
box is displayed. Each time you change the state of a check
box, the status display is updated.
-
7/28/2019 AWT-part2
26/157
-
7/28/2019 AWT-part2
27/157
-
7/28/2019 AWT-part2
28/157
Handling Check Boxes
Sample output
-
7/28/2019 AWT-part2
29/157
CheckboxGroup
-
7/28/2019 AWT-part2
30/157
CheckboxGroup (radio buttons)
A set of mutually exclusive check boxes in which one and only one
check box in the group can be checked at any one time.
Check box groups are objects of type CheckboxGroup
Constructor :CheckboxGroup() creates an empty group
Methods:
1. Checkbox getSelectedCheckbox( ) get status
2. void setSelectedCheckbox(Checkbox which) set a check box
which the check box that you want to be selected
-
7/28/2019 AWT-part2
31/157
CheckboxGroup (radio buttons)
First define the group to which they will belong and then specify
that group when you construct the check boxes.
-
7/28/2019 AWT-part2
32/157
-
7/28/2019 AWT-part2
33/157
-
7/28/2019 AWT-part2
34/157
CheckboxGroup (radio buttons)
Output generated by the CBGroup applet is shown
-
7/28/2019 AWT-part2
35/157
Choice Controls
-
7/28/2019 AWT-part2
36/157
Choice Controls
A Choice control is a form of menu.
The Choice class is used to create a pop-up list of items from
which the user may choose
Each item in the list is a string that appears as a left-justified
label in the order it is added to the Choice object
Constructor (default):
Choice () creates an empty list.
Choice Controls
-
7/28/2019 AWT-part2
37/157
Choice Controls
Methods :
1. void add(String name) add a selection to the list
2. String getSelectedItem( ) returns a string containing the
name of the item
3. intgetSelectedIndex( )returns the index of the item
4. intgetItemCount( ) obtain the number of items in the list
5. void select(int index) select an item with a zero-based
integer index
6. void select(String name) select an item with a string
7. StringgetItem(int index) obtain the name associated with
the item at the given index.
-
7/28/2019 AWT-part2
38/157
Handling Choice Lists
Each time a choice is selected, an item event is
generated.
Each listener implements theItemListenerinterface
That interface defines the itemStateChanged( )
method
An ItemEvent object is supplied as the argument to
this method.
dli h i i
-
7/28/2019 AWT-part2
39/157
Handling Choice Lists
Here is an example that creates two Choice menus. One selects the
operating system. The other selects the browser.
-
7/28/2019 AWT-part2
40/157
-
7/28/2019 AWT-part2
41/157
-
7/28/2019 AWT-part2
42/157
-
7/28/2019 AWT-part2
43/157
-
7/28/2019 AWT-part2
44/157
Using Lists
-
7/28/2019 AWT-part2
45/157
Using Lists
The List class provides a compact, multiple-choice, scrolling
selection list
Constructors :
1. List( ) creates a List control that allows only one item to be
selected at any one time.
2. List(int numRows) The value of numRows specifies the
number of entries in the list that will always be visible.
3. List(int numRows, boolean multipleSelect) If
multipleSelect is true, then the user may select two or more
items at a time.
-
7/28/2019 AWT-part2
46/157
Methods :
1. void add(String name) adds items to the end of
the list
2. void add(String name, int index) adds the item
at the index specified by index
3. String getSelectedItem( ) returns a string
containing the name of the item.
4. int getSelectedIndex() returns the index of the
item
Using Lists
M h d
-
7/28/2019 AWT-part2
47/157
Methods :
5. String[ ] getSelectedItems( ) returns an array
containing the names of the currently selected items.
6. int[ ] getSelectedIndexes( ) returns an array
containing the indexes of the currently selected items.
7. int getItemCount( ) obtain the number of items in the
list
8. void select(int index)
set the currently selected item
9. String getItem(int index) obtain the name associated
with the item at the index
Handling Lists
-
7/28/2019 AWT-part2
48/157
you will need to implement the ActionListener interface
Each time a List item is double-clicked, an ActionEvent object isgenerated
Its getActionCommand( ) method can be used to retrieve the
name of the newly selected item
Each time an item is selected or deselected with a single click,
an ItemEvent object is generated
Its getStateChange( ) method can be used to determine
whether a selection or deselection triggered this event
getItemSelectable( ) returns a reference to the object that
triggered this event.
Handling Lists
-
7/28/2019 AWT-part2
49/157
Here is an example that converts the Choice controls in the preceding
section into List components, one multiple choice and the other
single choice:
-
7/28/2019 AWT-part2
50/157
-
7/28/2019 AWT-part2
51/157
-
7/28/2019 AWT-part2
52/157
-
7/28/2019 AWT-part2
53/157
Managing Scroll Bars
-
7/28/2019 AWT-part2
54/157
Managing Scroll Bars
-
7/28/2019 AWT-part2
55/157
g g
Constructors
1. Scrollbar() creates a vertical scroll bar.2. Scrollbar(int style)
style specifies the orientation . style can be
Scrollbar.VERTICAL
Scrollbar.HORIZONTAL
3. Scrollbar(int style, int initialValue, int thumbSize, int min, int max)
initialValuethe initial value of the scroll bar
thumbSize The number of units represented by the height of the thumb
min , max The minimum and maximum values for the scroll bar
Managing Scroll Bars
-
7/28/2019 AWT-part2
56/157
g g
Methods :
1. void setValues(int initialValue, int thumbSize, int min, int max)
set its parameters
2. int getValue( ) obtain the current value of the scroll bar
3. void setValue(int newValue) set the current value
4. int getMinimum( ) retrieve the minimum values
5. int getMaximum( ) retrieve the maximum values
6. void setUnitIncrement(int newIncr)change the increment (default : 1)
7. void setBlockIncrement(int newIncr) page-up and page-down increments
(default : 10)
Handling Scroll Bars
-
7/28/2019 AWT-part2
57/157
Interaction with a scroll bar, generates an Adjustment Event
you need to implement the AdjustmentListener interface
This interface defines adjustmentValueChanged() method
which takes AdjustmentEvent object as the argument
getAdjustmentType() ofAdjustmentEvent can be used to
determine the type of the adjustment.
g
Handling Scroll Bars
-
7/28/2019 AWT-part2
58/157
g
The types of adjustment events are as follows:
Handling Scroll Bars
-
7/28/2019 AWT-part2
59/157
The following example creates both a vertical and a horizontal scroll bar. If you
drag the mouse while inside the window, the coordinates of each drag event
are used to update the scroll bars. An asterisk is displayed at the current drag
position.
g
Handling Scroll Bars
-
7/28/2019 AWT-part2
60/157
g
Handling Scroll Bars
-
7/28/2019 AWT-part2
61/157
Handling Scroll Bars
-
7/28/2019 AWT-part2
62/157
Handling Scroll Bars
-
7/28/2019 AWT-part2
63/157
Handling Scroll Bars
-
7/28/2019 AWT-part2
64/157
Sample output
-
7/28/2019 AWT-part2
65/157
Using a TextField
Using a TextField
-
7/28/2019 AWT-part2
66/157
The TextField class implements a single-line text-entry area,
usually called an edit control.
TextField is a subclass ofTextComponent
Constructors :
1. TextField( ) creates a default text field
2. TextField(int numChars) creates a text field that is
numChars characters wide
3. TextField(String str)initializes the text field with the string
4. TextField(String str, int numChars) initializes a text field
and sets its width
Using a TextField
-
7/28/2019 AWT-part2
67/157
Using a TextField
Methods
1. String getText( ) obtain the curent string
2. void setText(String str) To set the text
3. String getSelectedText( ) select a portion of the text
4. void select(int startIndex, int endIndex) obtain the
currently selected text
Using a TextField
-
7/28/2019 AWT-part2
68/157
Using a TextField
Methods
5. void setEditable(boolean canEdit) if canEdit is true, thetext may be changed. If it is false, the text cannot be altered
6. boolean isEditable( ) determine editability7. void setEchoChar(char ch) disable the echoing of the
characters
8. boolean echoCharIsSet( ) check a text field to see if it is inthis mode
9. char getEchoChar( ) retrieve the echo character
Handling a TextField
-
7/28/2019 AWT-part2
69/157
Handling a TextField
Text Field generates Action Event when ENTER key is pressed.
-
7/28/2019 AWT-part2
70/157
-
7/28/2019 AWT-part2
71/157
-
7/28/2019 AWT-part2
72/157
Sample output
-
7/28/2019 AWT-part2
73/157
Using a TextArea
Using a TextArea
-
7/28/2019 AWT-part2
74/157
Using a TextArea
AWT includes a simple multiline editor called TextArea
TextArea is a subclass ofTextComponent
Constructors :
1. TextArea( )
2. TextArea(int numLines, int numChars)
3. TextArea(String str)
4. TextArea(String str, int numLines, int numChars)
5. TextArea(String str, int numLines, int numChars, int sBars)
Using a TextArea
-
7/28/2019 AWT-part2
75/157
Using a TextArea
Constructors :
numLines specifies the height, in lines,
numCharsspecifies its width, in characters.
str Initial text
sBars must be one of these values :
SCROLLBARS_BOTH
SCROLLBARS_NONE
SCROLLBARS_HORIZONTAL_ONLY
SCROLLBARS_VERTICAL_ONLY
Using a TextArea
-
7/28/2019 AWT-part2
76/157
Using a TextArea
Methods :
Supports the getText( ), setText( ), getSelectedText( ), select( ), isEditable( ), and
setEditable( ) methods. In addition to these, TextArea adds the following
methods:
1. void append(String str) appends the string specified by str to
the end of the currenttext.
2. void insert(String str, int index) inserts the string passed in
strat the specified index
3. void replaceRange(String str, int startIndex, int endIndex)
replaces the characters from startIndex to endIndex1, withthe replacement text passed in str.
Using a TextArea
-
7/28/2019 AWT-part2
77/157
Using a TextArea
Text areas only generate got-focus and lost-focus events.
Normally, your program simply obtains the current text when it is
needed. The following program creates a TextArea control
Using a TextArea
-
7/28/2019 AWT-part2
78/157
Using a TextArea
Using a TextArea
-
7/28/2019 AWT-part2
79/157
g
sample output
Understanding Layout Managers
-
7/28/2019 AWT-part2
80/157
Understanding Layout Managers
Each Container object has a layout manager associated with it.
The layout manager is set by the setLayout( ) method
void setLayout(LayoutManager layoutObj)
layoutObj A reference to the desired layout manager
pass null for layoutObj If you wish to disable thelayout manager.
-
7/28/2019 AWT-part2
81/157
FlowLayout
-
7/28/2019 AWT-part2
82/157
y
FlowLayout is the default layout manager.
Components are laid out from the upper-left corner, left to
right and top to bottom.
Constructors for FlowLayout
1. FlowLayout( )
2. FlowLayout(int how)
3. FlowLayout(int how, int horz, int vert)
FlowLayout
-
7/28/2019 AWT-part2
83/157
y
Constructors for FlowLayout
1. The first form creates the default layout, which centerscomponents and leaves five pixels of space between each
component
2. The second form lets you specify how each line is aligned.
Valid values forhow are as follows:
1. FlowLayout.LEFT
2. FlowLayout.CENTER
3. FlowLayout.RIGHT
4. FlowLayout.LEADING
5. FlowLayout.TRAILING
FlowLayout
-
7/28/2019 AWT-part2
84/157
y
Constructors for FlowLayout
3. The third form allows you to specify the horizontal and
vertical space left between components
Here is a version of the CheckboxDemo applet( the controls are left aligned )
FlowLayout
-
7/28/2019 AWT-part2
85/157
FlowLayout
-
7/28/2019 AWT-part2
86/157
FlowLayout
-
7/28/2019 AWT-part2
87/157
FlowLayout
-
7/28/2019 AWT-part2
88/157
sample output
BorderLayout
-
7/28/2019 AWT-part2
89/157
The BorderLayout class implements a common layout
style for top-level windows.
It has four narrow, fixed-width components at the
edges and one large area in the center.
The four sides are referred to as north, south, east, and
west. The middle area is called the center.
BorderLayout
-
7/28/2019 AWT-part2
90/157
Constructors defined by BorderLayout
1. BorderLayout( ) Creates a default border layout.
2. BorderLayout(int horz, int vert)
Allows you to specify the horizontal and vertical
space left between components in horzand vert
BorderLayout defines the following constants that specify the
-
7/28/2019 AWT-part2
91/157
BorderLayout defines the following constants that specify the
regions:
BorderLayout.CENTER
BorderLayout.SOUTH
BorderLayout.EAST
BorderLayout.WEST
BorderLayout.NORTH
Use these constants with the following form of add( ), which is
defined by Container:
void add(Component compObj, Object region);
region specifies where the componentwill be added.
Here is an example of a BorderLayout with a component in each
-
7/28/2019 AWT-part2
92/157
Here is an example of a BorderLayout with a component in each
layout area
-
7/28/2019 AWT-part2
93/157
-
7/28/2019 AWT-part2
94/157
Sample output
Using Insets
-
7/28/2019 AWT-part2
95/157
To leave a small amount of space between the container that
holds your components and the window that contains it. To
do this :
Override the getInsets( ) method that is defined by Container
Insets getInsets( )
returns an Insets object that containsthe top, bottom, left, and right inset
Constructor for Insets
Insets(int top, int left, int bottom, int right)
-
7/28/2019 AWT-part2
96/157
-
7/28/2019 AWT-part2
97/157
Using Insets
-
7/28/2019 AWT-part2
98/157
Using Insets
-
7/28/2019 AWT-part2
99/157
Output from the InsetsDemo applet
GridLayout
-
7/28/2019 AWT-part2
100/157
GridLayout lays out components in a two-dimensional grid.
The constructors supported
1. GridLayout( ) creates a single-column grid layout
2. GridLayout(int numRows, int numColumns )
3. GridLayout(int numRows, int numColumns, int horz, int vert)
The third form allows you to specify the horizontal and vertical
space left between components in horz andvert, respectively.
numRow , numColumns specified number of rows and columns
GridLayout
-
7/28/2019 AWT-part2
101/157
Here is a sample program that creates a 44 grid and fills it in with
15 buttons, each labeled with its index:
GridLayout
-
7/28/2019 AWT-part2
102/157
GridLayout
-
7/28/2019 AWT-part2
103/157
the output generated by the GridLayoutDemo applet:
CardLayout
-
7/28/2019 AWT-part2
104/157
It stores several different layouts
Each layout can be thought of as being on a separate
index card in a deck
The deck can be shuffled so that any card is on top at a
given time
useful for user interfaces with optional components
that can be dynamically enabled and disabled upon user
input
CardLayout
-
7/28/2019 AWT-part2
105/157
Provides these two constructors
1. CardLayout( )
2. CardLayout(int horz, int vert)
The first form creates a default card layout
The second form allows you to specify the horizontal
and vertical space left between components in horz and
vert, respectively
-
7/28/2019 AWT-part2
106/157
-
7/28/2019 AWT-part2
107/157
-
7/28/2019 AWT-part2
108/157
-
7/28/2019 AWT-part2
109/157
-
7/28/2019 AWT-part2
110/157
-
7/28/2019 AWT-part2
111/157
-
7/28/2019 AWT-part2
112/157
-
7/28/2019 AWT-part2
113/157
d
-
7/28/2019 AWT-part2
114/157
Menu Bars and Menus
-
7/28/2019 AWT-part2
115/157
Steps to create Menus
1 first create an instance of MenuBar
-
7/28/2019 AWT-part2
116/157
1. first create an instance ofMenuBar
2. Next, create instances of Menu that will define the selections
displayed on the bar
constructors for Menu:
1. Menu( )2. Menu(String optionName)3. Menu(String optionName, boolean removable)
optionName
specifies the name of the menu selection.removable If removable is true, the pop-up menu can be
removed and allowed to float free.
Steps to create Menus
To cretate menu items use MenuItems constructors :
-
7/28/2019 AWT-part2
117/157
To cretate menu items use MenuItems constructors :
1. MenuItem( )
2. MenuItem(String itemName)
3. MenuItem(String itemName, MenuShortcut keyAccel)
itemNamethe name shown in the menu,
keyAccel is the menu shortcut forthis item.
-
7/28/2019 AWT-part2
118/157
CheckboxMenuItem
-
7/28/2019 AWT-part2
119/157
You can create a checkable menu item by using a subclass
ofMenuItem called CheckboxMenuItem
1. CheckboxMenuItem( )
2. CheckboxMenuItem(String itemName)
3. CheckboxMenuItem(String itemName, boolean on)
itemName the name shown in the menu
on ifon is true, the checkable entry is initially checked.
CheckboxMenuItem
You can obtain the status of a checkable item by calling
-
7/28/2019 AWT-part2
120/157
You can obtain the status of a checkable item by calling
getState( ).
You can set it to a known state by using setState( ).
boolean getState( ) returns true if checked. Otherwise, it
returns false
void setState(boolean checked) checked must be TRUE
to check an item
Adding Menu item and Menu Bar
Add the item to a Menu object by using add( )
-
7/28/2019 AWT-part2
121/157
Add the item to a Menu object byusing add( ),
MenuItem add(MenuItem item)
Item the item being added. The item is returned.
Once you have added all items to a Menu object, you can add that
object to the menu bar by using this version of add( ) defined by
MenuBar:
Menu add(Menu menu)
menu the menu being added. The menu is returned
Handling Menus
-
7/28/2019 AWT-part2
122/157
Menus only generate events when an item of type MenuItem or
CheckboxMenuItem is selected.
Each time a menu item is selected, an ActionEvent object is
generated.
Each time a check box menu item is checked or unchecked, an
ItemEvent object is generated
Thus, you must implement the ActionListener and ItemListener
interfaces in order to handle these menu events.
-
7/28/2019 AWT-part2
123/157
-
7/28/2019 AWT-part2
124/157
-
7/28/2019 AWT-part2
125/157
-
7/28/2019 AWT-part2
126/157
-
7/28/2019 AWT-part2
127/157
-
7/28/2019 AWT-part2
128/157
-
7/28/2019 AWT-part2
129/157
-
7/28/2019 AWT-part2
130/157
-
7/28/2019 AWT-part2
131/157
-
7/28/2019 AWT-part2
132/157
-
7/28/2019 AWT-part2
133/157
-
7/28/2019 AWT-part2
134/157
Dialog Boxes
-
7/28/2019 AWT-part2
135/157
Dialog Boxes
-
7/28/2019 AWT-part2
136/157
Dialog boxes are of type Dialog.
Two commonly used constructors :
1. Dialog(Frame parentWindow, boolean mode)
2. Dialog(Frame parentWindow, String title, boolean mode)
parentWindow the owner of the dialog box.
mode If mode is true, the dialog box is modal
title title of the dialog box
Generally, you will subclass Dialog, adding the functionality
required by your application
Dialog Boxes
Following is a modified version of the preceding menu program
-
7/28/2019 AWT-part2
137/157
Following is a modified version of the preceding menu program
that displays a modeless dialog box when the New option ischosen.
-
7/28/2019 AWT-part2
138/157
-
7/28/2019 AWT-part2
139/157
-
7/28/2019 AWT-part2
140/157
-
7/28/2019 AWT-part2
141/157
-
7/28/2019 AWT-part2
142/157
-
7/28/2019 AWT-part2
143/157
-
7/28/2019 AWT-part2
144/157
-
7/28/2019 AWT-part2
145/157
-
7/28/2019 AWT-part2
146/157
-
7/28/2019 AWT-part2
147/157
-
7/28/2019 AWT-part2
148/157
-
7/28/2019 AWT-part2
149/157
-
7/28/2019 AWT-part2
150/157
FileDialog
-
7/28/2019 AWT-part2
151/157
To create a file dialog box, instantiate an object of type
FileDialog.
This causes a file dialog box to be displayed.
FileDialog provides these constructors:
1. FileDialog(Frame parent, String boxName)
2. FileDialog(Frame parent, String boxName, int how)
3. FileDialog(Frame parent)
FileDialog
-
7/28/2019 AWT-part2
152/157
parent the owner of the dialog box,
boxName the name displayed in the boxs title bar.
If boxName is omitted, the title of the dialog box is empty.
how if FileDialog.LOAD, then the box is selecting a file for
reading.
If how is FileDialog.SAVE, the box is selecting a file for writing
FileDialog
FileDialog( ) id th f ll i th d
-
7/28/2019 AWT-part2
153/157
FileDialog( ) provides the following methods
1. String getDirectory( )
2. String getFile( )
These methods return the directory and the filename, respectively.
-
7/28/2019 AWT-part2
154/157
-
7/28/2019 AWT-part2
155/157
-
7/28/2019 AWT-part2
156/157
The output generated by this program
-
7/28/2019 AWT-part2
157/157
The output generated by this program