1. GUI Components

2. Structure

3. Container Class Structure

4. Component Class Methods
setBackground(c)
setForeground(c)
setFont(f)
setVisible(b)
paint(g)
repaint()
setSize(x,y)
getSize().width
getWidth()
getSize().height
getHeight()

5. Container Class Methods
add(x)
remove(x)
removeAll()
setLayout(l)
getLayout()
pack() -- window only
paint(g)
setVisible(b)
getComponents()

6. Layout Managers
FlowLayout: Places components from left to right, top to bottom allowing you no control over position.
Constructors:
FlowLayout(): the components are centered
FlowLayout(a): a is FlowLayout.LEFT or FlowLayout.RIGHT
FlowLayout(a, dx, dy) dx & dy are distances between components.

7. BorderLayout
Designates five positions in the screen: North, South, East, West, and Center.
BorderLayout(dx, dy) dx & dy are distances between components
add(“place”, c) : arranges the component c
“place” can be North, South, East, West, or Center

8. Border Layout Example /* File: BorderLayoutDemo.java */
import java.awt.*; import java.applet.Applet; public class BorderLayoutDemo extends Applet { public void init() { setLayout(new BorderLayout()); add(new Button("North") ,BorderLayout.NORTH); add(new Banner("The Center") ,BorderLayout.CENTER); add(new Button("East") ,BorderLayout.EAST); add(new Button("West") ,BorderLayout.WEST); add(new Button("South") ,BorderLayout.SOUTH); }
} // BorderLayoutDemo class

9. GridLayout
Lets you specify a two-dimensional grid of rows and columns.
All components are the same size, and the size will automatically change as the window is manipulated.
GridLayout(r,c) : sets number of rows and columns (Use zero when you need an arbitrary number)
GridLayout(r,c,dx,dy) dx & dy are spacing distances

10. GridLayout Example
/* File: GridLayoutDemo.java */ import java.awt.*; import java.applet.Applet; public class GridLayoutDemo extends Applet{ public void init() { int rows = 3; int columns = 3; Panel gridP = new Panel(); gridP.setLayout(new GridLayout(rows,columns,5,10)); for(int r = 1; r <= rows; r++) for (int c = 1; c <= columns; c++) if (r == 2 && c == 2) gridP.add(new Banner("TheCenter")); else gridP.add(new Button(r + " , " + c)); add(gridP); }
}// class GridLayoutDemo

11. CardLayout
Lets you create a “stack of cards” where only one of the cards is visible at any given time.

12. CardLayout Demo /* File: CardDemo.java*/
import java.awt.*; import java.applet.Applet; import java.awt.event.*;
public class CardDemo extends Applet implements ActionListener {
Button first,prev,next,last;
Panel displays;
CardLayout cLayout;
public void init() {
// The applet has a border layout
setLayout(new BorderLayout());
// Create the buttons for controlling the card panel.
// The button panel defaults to a FlowManager
Panel buttonP = new Panel();
first = new Button("First");
buttonP.add(first);
prev = new Button("Previous");
buttonP.add(prev);
next = new Button("Next");
buttonP.add(next);
last = new Button("Last");
buttonP.add(last);
add(buttonP,BorderLayout.SOUTH);
first.addActionListener(this);
prev.addActionListener(this);
next.addActionListener(this);
last.addActionListener(this);

13. CardLayout Demo // Create the card panel, and card layout
displays = new Panel();
for(int i = 1; i <= 5; i++)
displays.add( new Banner("Picture " + i));
cLayout = new CardLayout();
displays.setLayout(cLayout);
add(displays, BorderLayout.CENTER); }
public void actionPerformed(ActionEvent e) {
Button b = (Button)e.getSource();
if (b == next)
cLayout.next(displays);
else if (b == prev)
cLayout.previous(displays);
else if (b == last)
cLayout.last(displays);
else if (b == first)
cLayout.first(displays);
} // class CardDemo

14. CardLayout Demo

15. GridBagLayout The most complicated an powerful LayoutManager.
Separates the window into a number of boxes.
You may set the size of rows and columns of boxes
Components may span multiple boxes (display area)
You specify the box(es) that hold a component
Number of total boxes is based on component placement
Declaration: GridBagLayout m = new GridBagLayout(); setLayout(m);

16. GridBagConstraints()
Each component in a GridBagLayout must use an instance of the GridBagConstraints class to set its properties.
For example:
GridBagConstraints con = new GridBagConstraints();
con.X; con.Y; ... (uses methods X & Yof con to set some properties)
m.setConstraints(comp, con); connects the constrains in GridBagConstraints con to the component comp in GridBagLayout m.
The component can then be added to m with add(comp);

17. GridBagConstraints methods:
gridx, gridy: set column and row where component will begin. Starts with 0. Default value is Relative (to the right for gridx, down for gridy
gridwidth, gridheight: sets the number of boxes the component will occupy. Default is 1. Value REMAINDER means the rest of the row or col.
fill, anchor: deal with how the component will fill its area and/or what position in the box it will take (anchor). Default values: NONE, CENTER
insets, ipadx, ipady: allow you to set space around components.
weightx, weighty: set up how any extra space is allotted to components in each column (x) or row (y). Components with higher weight get more space. Default values: 0.

18. GridBagLayout Example:
// File: GridBagLayoutDemo.java
import java.awt.*; import java.applet.*;
public class GridBagLayoutDemo extends Applet { public void init() { GridBagLayout manager = new GridBagLayout(); setLayout(manager); GridBagConstraints constraints;
// arrange the checkboxes Checkbox chkBig = new Checkbox("Big"); Checkbox chkActive = new Checkbox("Active");
constraints = new GridBagConstraints(); constraints.weighty = 1;
constraints.anchor = GridBagConstraints.SOUTHWEST; constraints.gridy = 0; constraints.gridx = 0; // row 0, col manager.setConstraints(chkBig, constraints); add(chkBig);
constraints.anchor = GridBagConstraints.NORTHWEST; constraints.gridy = 1; constraints.gridx = 0; // row 1, col manager.setConstraints(chkActive, constraints); add(chkActive);

19. GridBagLayout Example:
// arrange the canvas Canvas cvs = new Canvas(); cvs.setBackground(Color.darkGray);
constraints = new GridBagConstraints(); constraints.gridy = 0; constraints.gridx = 1; // row 0, col constraints.gridwidth = 2; constraints.gridheight = 2; constraints.fill = GridBagConstraints.BOTH;
manager.setConstraints(cvs, constraints); add(cvs);
// arrange the label Label lblFile = new Label("File: ", Label.RIGHT); constraints = new GridBagConstraints(); constraints.gridy = 2; constraints.gridx = 0; // row 2, col constraints.insets = new Insets(10, 0, 10, 0); // 10 pixels above and below
manager.setConstraints(lblFile, constraints); add(lblFile);
// arrange the TextField TextField txtFile = new TextField(); constraints.gridwidth = 2; constraints.fill = GridBagConstraints.HORIZONTAL; constraints.gridy = 2; constraints.gridx = 1; // row 2, col 1
manager.setConstraints(txtFile, constraints); add(txtFile);

20. GridBagLayout Example:
// arrange the buttons Button btnOK = new Button("OK"); Button btnCancel = new Button("Cancel"); Button btnTest = new Button("Test");
constraints = new GridBagConstraints(); constraints.gridy = 3; constraints.gridx = 0; // row 3, col constraints.ipadx = 5; constraints.anchor = GridBagConstraints.EAST;
manager.setConstraints(btnOK, constraints); add(btnOK);
constraints.weightx = 1; constraints.gridy = 3; constraints.gridx = 1; // row 3, col constraints.anchor = GridBagConstraints.CENTER;
manager.setConstraints(btnCancel, constraints); add(btnCancel);
constraints.gridy = 3; constraints.gridx = 2; // row 3, col constraints.anchor = GridBagConstraints.WEST;
manager.setConstraints(btnTest, constraints); add(btnTest); } }

21. GridBagLayout Example:
<html> <head> <title>GridBagLayout demonstration</title> </head>
<body> <applet code=GridBagLayoutDemo.class width= height=200> </applet> </body> </html>

22. Output Components Label -- basic text output using fonts.
Canvas -- area for drawing or writing text.

23. The Label Component Methods:
Constructors: Label(“text”); Label(“text”,adj);
text is the label’s text, adj is the label’s alignment
setText(“text”); getText(); setAlignment(adj); getAlignment();
Values for adj: Label.LEFT (the default), Label.CENTER, Label.RIGHT

24. Label Example: import java.awt.*; class ShowLabel extends Frame {
public static void main(String[] arg) { ShowLabel w = new ShowLabel ();
Label l = new Label("Welcome to Java", Label.CENTER); l.setFont( new Font("SansSerif", Font.BOLD, 24) ); l.setBackground(Color.yellow); l.setForeground(Color.blue);
// set the window's properties w.setLayout( new GridLayout(1,1) ); w.add(l); w.setSize(400, 150); w.setVisible(true); } }

25. Canvas Used only for showing drawings & text
Not a container, like Panel.
import java.awt.*;
public class CircleCanvas extends Canvas { public boolean filled = true; public boolean inTheCenter = true; public boolean blackBackground = false;
public void paint(Graphics g) { int diam = Math.min(getSize().width, getSize().height); int x0 = 0;
if (inTheCenter) x0 = (getSize().width - diam) / 2; if (blackBackground) setBackground(Color.black); else setBackground(Color.white);
if (filled) g.fillOval(x0, 0, diam, diam); else g.drawOval(x0, 0, diam, diam); } }

26. Canvas Continued import java.awt.*; import java.applet.*;
public class CircleDemo extends Applet { CircleCanvas circle = new CircleCanvas();
Label label = new Label("A circle", Label.CENTER);
public void init() { circle.setForeground(Color.blue); label.setFont( new Font("Serif", Font.BOLD, 18) ); setLayout( new GridLayout(2, 1) ); add(circle); add(label);
setVisible(true); } }
<html> <head> <title>A canvas demonstration applet</title> </head>
<body> A canvas demonstration applet <br> <applet code=CircleDemo.class width= height=150> </applet> </body> </html>

27. Clickable Input Components
Button
CheckBox
List
Choice
Scrollbar

28. Button Define method actionPerformed in the listener: Methods:
Constructors: Button(); Button(“text”)
setLabel(“text”); getLabel()
b.setActionCommand(“text”); Connects the text text to button b.
b.addActionListener(l); Connects a listener l of class ActionListener to button b.
Define method actionPerformed in the listener:
Methods then called in the listener:
e.getSource(): returns the object where event occurred
b.getLabel(): returns text in button
public void actionPerformed(ActionEvent e) {
//we get here when the user presses the button }

29. Button Example: import java.awt.*; import java.awt.event.*;
import java.applet.*;
public class CircleButtonDemo extends Applet implements ActionListener {
private CircleCanvas circle = new CircleCanvas();
private Panel panel = new Panel();
private Button btnBlue = new Button("Blue");
private Button btnRed = new Button("Red");
private Button btnYellow = new Button("Yellow");
public void init() {
circle.setForeground(Color.green);
setLayout( new GridLayout(2, 1) );
add(circle);
add(panel);
panel.setLayout (new GridLayout(1, 3) );
panel.add(btnBlue);
panel.add(btnRed);
panel.add(btnYellow);

30. Button Example: // connect the listeners
btnBlue.addActionListener(this);
btnRed.addActionListener(this);
btnYellow.addActionListener(this);
setVisible(true); }
// define listeners
public void actionPerformed(ActionEvent e) {
// check to see which button has been clicked on
if (e.getSource() == btnBlue)
circle.setForeground(Color.blue);
else if (e.getSource() == btnRed)
circle.setForeground(Color.red);
else if (e.getSource() == btnYellow)
circle.setForeground(Color.yellow);
circle.repaint();

31. Button Example: <html> <head>
<title>A button demonstration applet</title>
</head>
<body>
A button demonstration applet <br>
<applet code=CircleButtonDemo.class
width=400
height=150>
</applet>
</body>
</html>

32. Checkboxes May be grouped to form radio buttons Declarations:
Checkbox x1 = new Checkbox(); not selected, no text
Checkbox x2 = new Checkbox(“text”); not selected, with text
Checkbox x3 = new Checkbox(“text”, false); not selected
Checkbox x4 = new Checkbox(“text”, true); selected
CheckboxGroup gr = new CheckboxGroup(); a set of radio buttons
Checkbox r1 = new Checkbox(“text1”,bool, gr);
Checkbox r2 = new Checkbox(“text2”,bool, gr);only one r# is true
Checkbox r3 = new Checkbox(“text3”,bool, gr);

33. Checkbox Methods setLabel(“text); getLabel(); setState(bool);
x.setCheckboxGroup(g); puts x into group g.
x.getCheckboxGroup(); gives the group x is in.
g.setSelectedCheckbox(x); x in group g will be selected
g.getSelectedCheckbox(); return selected Checkbox in g.

34. Checkbox Listeners To connect a listener to a Checkbox:
x.addItemListener(l);
Define the method itemStateChanged in the listener:
public void itemStateChanged (ItemEvent e) {
// we get here when user clicks on a checkbox }
Method called in the listener:
e.getSource(); returns the object where the event occurred.

35. Checkbox Example import java.awt.*; import java.awt.event.*;
import java.applet.*;
public class CircleCheckboxDemo extends Applet implements ItemListener {
private CircleCanvas circle = new CircleCanvas();
private Panel panelMiddle = new Panel();
private CheckboxGroup grpOption = new CheckboxGroup();
private Checkbox chkBlue = new Checkbox("Blue", true, grpOption);
private Checkbox chkRed = new Checkbox("Red", false, grpOption);
private Checkbox chkYellow = new Checkbox("Yellow", false, grpOption);
private Panel panelBottom = new Panel();
private Checkbox chkFilled = new Checkbox("Filled", true);
private Checkbox chkCentered = new Checkbox("Centered", true);
private Checkbox chkBlack = new Checkbox("Black Background", false);

36. public void init() { circle. setForeground(Color
public void init() { circle.setForeground(Color.green); setLayout (new GridLayout(3, 1) ); add(circle); add(panelMiddle); // arrange the radio buttons panelMiddle.setLayout( new GridLayout(1, 3) ); panelMiddle.add(chkBlue); panelMiddle.add(chkRed); panelMiddle.add(chkYellow); // connect the listener chkBlue.addItemListener(this); chkRed.addItemListener(this); chkYellow.addItemListener(this); add(panelBottom); // arrange the checkboxes panelBottom.setLayout( new GridLayout(3, 1) ); panelBottom.add(chkFilled); panelBottom.add(chkCentered); panelBottom.add(chkBlack);

37. Checkbox Example:
// connect the listener chkFilled.addItemListener(this); chkCentered.addItemListener(this); chkBlack.addItemListener(this); setVisible(true); } // listener public void itemStateChanged(ItemEvent e) { if (e.getSource() == chkBlue) circle.setForeground(Color.blue); else if (e.getSource() == chkRed) circle.setForeground(Color.red); else if (e.getSource() == chkYellow) circle.setForeground(Color.yellow); else if (e.getSource() == chkFilled || e.getSource() == chkCentered || e.getSource() == chkBlack) { circle.filled = chkFilled.getState(); circle.inTheCenter = chkCentered.getState(); circle.blackBackground = chkBlack.getState(); } circle.repaint(); } }

38. Choice and List
Choice chooses one item only while List allows for multiple selections at once.
Declarations:
Choice colors = new Choice(); colors.add(“Blue”); colors.add(“Red”); colors.add(“Yellow”);
List l = new list(3,true); //three items in list, all can be selected at once l.add(“Filled”); l.add(“In the center”); l.add(“Black Background”);

39. Choice and List Methods
x.add(“text”); Adds option text to x.
x.select(n); selects option n in x.
x.isIndexSelected(n); returns bool value
Connecting a listener:
X.addItemListener(l);
public void itemStateChanged(ItemEvent e) { //We get here when an option is selected or deselected. }
e.getSource(); returns the object where the event occurred.

40. Choice & List Example: import java.awt.*; import java.awt.event.*;
import java.applet.*;
public class CircleChoiceListDemo extends Applet implements ItemListener {
private CircleCanvas circle = new CircleCanvas();
private Panel panel = new Panel();
private Choice choColors = new Choice();
private List lstList = new List(3, true); // multi-select able
public void init() {
circle.setForeground(Color.green);
setLayout( new GridLayout(2, 1) );
add(circle);
add(panel);
panel.setLayout( new GridLayout(1, 2) );
panel.add(choColors);
// add the items to the choice menu
choColors.add("Blue");
choColors.add("Red");
choColors.add("Yellow");
// select the first item
choColors.select(0);
panel.add(lstList);

41. Choice & List Example: // add the item to the list
lstList.add("Filled");
lstList.add("Centered");
lstList.add("Black Background");
// select the first two items
lstList.select(0);
lstList.select(1);
// connect the listeners
choColors.addItemListener(this);
lstList.addItemListener(this);
// make visible
setVisible(true); }
public void itemStateChanged(ItemEvent e) {// listener
if (e.getSource() == choColors) {
if (choColors.getSelectedIndex() == 0)
circle.setForeground(Color.blue);
else if (choColors.getSelectedIndex() == 1)
circle.setForeground(Color.red);
else
circle.setForeground(Color.yellow); }
else if (e.getSource() == lstList) {
circle.filled = lstList.isIndexSelected(0);
circle.inTheCenter = lstList.isIndexSelected(1);
circle.blackBackground = lstList.isIndexSelected(2);
circle.repaint();

42. Choice & List Example:

43. Scrollbar Allows for ‘slider’ input Declaration:
Scrollbar sR = new Scrollbar(position, init.value, scrollbox, min.value, max.value);
Position is either Scrollbar.HORIZONTAL or Scrollbar.VERTICAL.
Scrollbox is size of the moveable box

44. Scrollbar Methods
setUnitIncrement(n); changes the amount of space moved when arrow is clicked by ±n
setPageIncrement(n); changes the amount of space moved when inside the bar is clicked by ±n
setValue(n); sets the value at scrollbox’s left/lower edge
getValue(n); gets the value at scrollbox’s left/lower edge
Listening: uses AdjustmentListener object instantiated as seen in Choice/List. Uses getSource();

45. Scrollbar Example: import java.awt.*; import java.awt.event.*;
import java.applet.*;
public class CircleScrollbarDemo extends Applet implements AdjustmentListener {
private CircleCanvas circle = new CircleCanvas();
private Panel panel = new Panel();
private Scrollbar sbRed = new Scrollbar(Scrollbar.HORIZONTAL, 0, 1, 0, 256);
private Scrollbar sbGreen = new Scrollbar(Scrollbar.HORIZONTAL, 255, 1, 0, 256);
private Scrollbar sbBlue = new Scrollbar(Scrollbar.HORIZONTAL, 0, 1, 0, 256);
private Label lblRed = new Label("0", Label.CENTER);
private Label lblGreen = new Label("255", Label.CENTER);
private Label lblBlue = new Label("0", Label.CENTER);

46. Scrollbar Example public void init() {
circle.setForeground(Color.green);
setLayout( new GridLayout(2, 1, 0, 5) );
add(circle);
add(panel);
panel.setLayout( new GridLayout(3, 3) );
panel.add( new Label("Red", Label.CENTER) ); panel.add(sbRed); panel.add(lblRed);
panel.add( new Label("Green", Label.CENTER) ); panel.add(sbGreen); panel.add(lblGreen);
panel.add( new Label("Blue", Label.CENTER) ); panel.add(sbBlue); panel.add(lblBlue);
sbRed.addAdjustmentListener(this);
sbGreen.addAdjustmentListener(this);
sbBlue.addAdjustmentListener(this);
setVisible(true); }

47. Scrollbar Example:
public void adjustmentValueChanged(AdjustmentEvent e) {
if (e.getSource() == sbRed || e.getSource() == sbGreen || e.getSource() == sbBlue) {
int red = sbRed.getValue(), green = sbGreen.getValue(), blue = sbBlue.getValue();
lblRed.setText( String.valueOf(red) );
lblGreen.setText( String.valueOf(green) );
lblBlue.setText( String.valueOf(blue) );
circle.setForeground( new Color(red, green, blue) );
circle.repaint(); }

48. Text Input TextField -- one line, or row, of text
TextArea -- multiple rows

49. TextField Methods Declarations: Uses ActionListener
TextField t = new TextField();
TextField t = new TextField(n); n sets space
TextField t = new TextField(“text”);
TextField t = new TextField(“text, n);
Uses ActionListener
e.getSource();
x.getText(); Returns the text in the box as a String (which must be parsed for numeric data)

50. TextField Methods setColumns(n) -- Changes the size setText(“text”)
setEchoChar(‘*’) -- Displays in place of entered text. Used for password fields.
selectAll()
select(i, j) -- Selects characters i to j
getSelectedText

51. TextField Example: import java.awt.*; import java.awt.event.*;
class Hello extends Frame implements ActionListener {
TextField txtAnswer = new TextField(25);
Label lblGreeting = new Label();
public Hello() {// constructor
// define the appearance of the window
setFont( new Font("Dialog", Font.PLAIN, 14) );
setLayout( new GridLayout(2, 2) );
add( new Label("What is your name? ", Label.RIGHT) ); // add the components
add(txtAnswer);
add(lblGreeting);
lblGreeting.setAlignment(Label.RIGHT);
pack(); // pack the window, calculating its size
txtAnswer.addActionListener(this); // connect a listener to the TextField
// display the window
setVisible(true); }

52. TextField Example: public static void main(String[] arg) {
Hello h = new Hello(); }
// listeners
public void actionPerformed(ActionEvent e) {
// this method is called when an event occurs
if (e.getSource() == txtAnswer) {
String name = txtAnswer.getText();
lblGreeting.setText("Welcome " + name + "!");

53. TextArea Methods Declaration:TextArea a=new TextArea(“text”,r,c,sb);
r & c -- number of rows & columns
sb sets scrollbars
All methods in TextField are available plus:
setEditable(bool)
append(“text”)
insert(“text”, i)
replaceRange(“text”, i, j)

54. TextArea Methods Continued
setRows( r) setColumns( c) getRows() getColumnts()
Must use a TextListener, not an ActionListener
a.addTextListener(l);
public void textValueChanged(TextEvent e) { // we get here when the user makes changes in the text }
e.getSource(); //returns object where event occurred

55. Containers
Panel
ScrollPane

56. Panel Is a subclass of Component
Has its own layout, therefore its own LayoutManager can be used.
Must be contained by another container.

57. Panel Example import java.awt.*; class Flight extends Panel {
String flightNo, destination,
comment = " ";
Time departure, arrival;
Label comLabel = new Label(comment);
public Flight(String flight, String dest,
int depHour, int depMin,
int arrHour, int arrMin) {
flightNo = flight;
destination = dest;
departure = new Time(depHour, depMin);
arrival = new Time(arrHour, arrMin);
setLayout( new GridLayout(1, 4) );
setBackground(Color.white);
departure.setFont( getFont() );
departure.setBackground( getBackground() );
add( new Label(flightNo) );
add( new Label(destination) );
add(departure);
add(comLabel);
setVisible(true); }
public void delay(int min) {
departure.tick(min * 60);
arrival.tick(min * 60);
setComment("Delayed");
public void setComment(String theComment) {
comment = theComment;
comLabel.setText(comment);
repaint();

58. Panel Example import java.awt.*; class FlightDemo extends Frame {
Flight f1, f2, f3, f4;
public FlightDemo() {
f1 = new Flight("BA1853", "London", 8, 10, 10, 55);
f2 = new Flight("AF3142", "Paris", 8, 20, 10, 55);
f3 = new Flight("TP0678", "Lisbon", 8, 35, 12, 40);
f4 = new Flight("SK5971", "Vern", 8, 40, 9, 30);
add(f1);
add(f2);
add(f3);
add(f4);
setLayout( new GridLayout(4, 1, 0, 1) );
setBackground(Color.black);
pack(); // resize window
setVisible(true);
f1.delay(15);
f2.setComment("Boarding gate 15"); }
public static void main(String[] arg) {
FlightDemo demo = new FlightDemo(); }

59. ScrollPane Declaration: add( c)
new ScrollPane(); new ScrollPane(s)
s -- ScrollPane.SCROLLBARS.ALWAYS/NEVER
add( c)
getScrollbarHeight(); getScrollbarWidth();
setScrollbarPosition(x,y); allows point x,y to be seen

60. ScrollPane Example import java.awt.*; import java.applet.*;
public class ScrollPaneDemo extends Applet {
private ScrollPane sp = new ScrollPane();
private CircleCanvas circle = new CircleCanvas();
public void init() {
circle.setSize(300, 300);
sp.add(circle);
setLayout( new GridLayout(1, 1) );
add(sp);
setVisible(true); }