[public] interface [extends ]
:
public interface Product
{
static final String MAKER = Cisco Corp.;
static final String Phone = 555-123-4567;
public int getPrice(int id);
}
java.applet:
public interface AudioClip
{ /** Starts playing the clip.
Each time this method is called,
the clip is restarted from the beginning. */
void play();
/** Starts playing the clip in a loop.
*/
void loop();
/** Stops playing the clip.
*/
void stop();
}
, , .
, , , :
interface Monitored extends java.lang.Runnable, java.lang.Clonable
{
boolean IsRunning();
}
, , , , . , , , . , :
class Shoe implements Product
{ public int getPrice(int id)
{
if (id==1) return 5;
else return 10;
}
public String getMaker()
{
return MAKER;
}
}
, , Java, ' . java.awt (Abstract Window Toolkit), 2.3.
| TextComponent |
| TextField |
| TextArea |
| Container |
| Panel |
| Window |
| Frame |
| Dialog |
| File Dialog |
| Applet |
| Component |
| Canvas |
| List |
| Label |
| Button |
| Checkbox |
| Choice |
| Scrollbar |
| Menu Component |
| MenuBar |
| MenuItem |
| Menu |
| CheckboxMenuItem |
2.3 java.awt
, awt? Java, (GUI). Component. MenuComponent. : Button (), Checkbox ( ), Choice ( Windows), Label (), List ( Windows) Scrollbar ( ). , Component .
java.awt , . Panel . - Container, -, . ³ Window, . : Dialog, , Frame Windows. TextComponent TextField ( Windows) TextArea. Canvas. , 䳿 .
|
|
|
³ Component , ' . , , ( 3):
2.3
Component
| getFont() setFont() getFontMetrics() | |
| setForeground() getForeground() | |
| setBackground() getBackground() | |
| preferredSize() minimumSize() | , |
| resize() size() | |
| show() hide() | |
| isVisible() isShowing() | true, , false, |
| disable() enable() | |
| isEnable() | true, |
| paint() update() repaint() | |
| handleEvent() action() | |
| keyDown() keyUp() |
Label ():
Label Java- . ᒺ :
Label(); //
Label(String str); // ,
Label(String str, int align); //
align : Label.LEFT, Label.CENTER, Label.RIGHT.
Label 4.
2.4
Label
| SetText(String str) | |
| setAlignment(int align) | |
| String getText() | |
| int getAlignment() |
.
Label MyLabel1 = new Label( , Label.CENTER);
Label MyLabel2 = new Label( );
Button ():
Button . . , :
Button(); //
Button(String str); //
:
setLabel() ;
getLabel() .
. action():
public boolean action(Event evt, Object wA);
evt , (evt.target ᒺ , evt.when 䳿,...);
wA .
:
...
public class Example1 extends Applet
{
public void init()
{
add(new Button(Red);
add(new Button(Green);
}
public Boolean action(Event e, Object wA)
{
if (!(e.target instanceof Button))
// ,
|
|
|
return false;
if ((String) wA = Red) // ?
setBackground(Color.red);
else
setBackground(Color.green);
return true;
Checkbox ( ):
Checkbox . , : "" "". , . ( false).
CheckboxGroup, (radio button), , . - , ( , ).
:
Checkbox(); //
Checkbox(String str); //
Checkbox(String str, CheckboGroup group, boolean initState);
/* , ( , , null */
2.5.
2.5
Checkbox
| boolean getState() | Checkbox, |
| getCurrent() | CheckboxGroup, , |
| SetCurrent() | ( CheckboxGroup) |
| setLabel() getLabel() |
. action(), wA ᒺ boolean, true, , false .
.
import java.awt.*;
import java.applet.*;
public class ExCheckbox extends Applet {
Checkbox rbBlue, rbWhite;
CheckboxGroup gr;
public void init() {
add (new Checkbox("Red"));
add (new Checkbox("Green"));
gr = new CheckboxGroup();
Checkbox rbBlue = new Checkbox("Blue",gr,true);
Checkbox rbWhite = new Checkbox("White",gr,false);
add(rbBlue);
add(rbWhite);
}
public boolean action(Event e, Object wA) {
if (e.target instanceof Checkbox)
{
Checkbox cur = (Checkbox) e.target;
if (cur.getLabel() == "Red" && cur.getState())
setBackground(Color.red);
if (cur.getLabel() == "Green" && cur.getState())
setBackground(Color.green);
if (cur.getLabel() == "Blue" && cur.getState())
setBackground(Color.blue);
if (cur.getLabel() == "White" && cur.getState())
setBackground(Color.white);
return true;
}
return false;
}
}
Choice (, ):
, , Choice.
Choice();
Choice 2.6:
2.6
Choice
| addItem(String str) | |
| select(int n) | |
| select(String str) | |
| int countItems() | |
| int getSelectIndex() | ( 0) |
| String getItem(int n) | |
| String getItem() |
, . action(), wA .
.
import java.awt.*;
import java.applet.*;
public class ExChoice extends Applet
{ Choice ch;
public void init()
{ ch=new Choice();
ch.addItem("Red");
ch.addItem("Green");
ch.addItem("Blue");
ch.addItem("White");
|
|
|
add(ch);
}
public boolean action(Event e, Object wA)
{
if (e.target instanceof Choice)
{
Choice cur = (Choice) e.target;
switch (cur.getSelectedIndex()) {
case 0: setBackground(Color.red); break;
case 1: setBackground(Color.green); break;
case 2: setBackground(Color.blue); break;
case 3: setBackground(Color.white); break;
} return true;
} return false;
}
}
List ():
List () Choice, , , , . - , , <Enter>. , .
List 2.7.
2.7
List
| addItem(String str) | ; |
| addItem(String str, int index) | index ( index = -1, ); |
| replaceItem(String str, int index) | |
| delItem(int index) | |
| delItems(int start, int end) | , start end; |
| getItem(int n) | |
| clear() | ( ) |
| select(int n) | |
| deselect(int n) | |
| isSelected(int n) | true, , false |
| countItems() | |
| getRows() | |
| getSelectedIndex() | ; -1, ( ) |
| getSelectedItem() | ( ); |
| int[] getSelectedIndexes() | ( ); |
| String[] getSelectedItems() | ( ) |
| allowsMultipleSelections() | true, |
| setMultipleSelections() | |
| makeVisible(int n) | |
| getVisibleIndex() | , makeVisible() |
' List . , addItem(). . . , .
:
List (); //
List (int row, boolean mult); // ,
// row ,
// , mult -
. List action().
handleEvent(Event evt);
evt.id , :
LIST_SELECT ;
LIST_DESELECT ;
evt.arg , .
.
import java.awt.*;
import java.applet.*;
public class ExList extends Applet
{ List ch;
public void init()
{ ch=new List();
ch.addItem("Red");
ch.addItem("Green");
|
|
|
ch.addItem("Blue");
ch.addItem("White");
ch.addItem("Cyan");
add(ch);
}
public boolean handleEvent(Event e)
{ if (e.target == ch)
{ if (e.id==Event.LIST_SELECT)
{
Integer sel=(Integer) e.arg;
switch (sel.intValue())
{
case 0: setBackground(Color.red); break;
case 1: setBackground(Color.green); break;
case 2: setBackground(Color.blue); break;
case 3: setBackground(Color.white); break;
case 4: setBackground(Color.cyan); break;
}
}
return true;
}
return false;
}
}
, TextField TextArea, TextComponent, . : (TextField) (TextArea). ' : TextField TextArea:
:
TextField(); //
TextField(int); //
TextField(String); //
TextArea(); //
TextArea(int, int); //
TextArea(String); //
TextArea(String, int, int); // /
TextField TextArea 2.8.
2.8
TextField TextArea
| getText() | |
| setText(String) | ; |
| select(int, int) | ; |
| selectAll() | |
| getSelectedText() | ; |
| SetEditable(Boolean) | |
| isEditable() | , |
| getSelectionStart() | |
| getSelectionEnd() | |
| getColumns() | ( !) |
. List, TextArea action(). 䳿 䳿 , , , , . ϳ getText() .
TextField . action(), , <Enter>.
-, Java (layout manager). ³ ' , . , , , setLayout(), :
setLayout(new BorderLayout());
FlowLayout ( ) - , . , .
:
FlowLayout(); //
FlowLayout(int align); //
FlowLayout(int align, int horp, int verp); //
//
//
align :
FlowLayout.LEFT, FlowLayout.RIGHT, FlowLayout.CENTER.
GridLayout . . .
:
GridLayout(int nRows, int nCols); //
//
GridLayout(int nRows, int nCols, int horp, int verp);
//
// ( )
, , . , 0. , 0. , GridLayout(3, 4) GridLayout(3, 0).
BorderLayout ( ) - 5 , . BorderLayout - add() , North, South, East, West Center. , .
:
|
|
|
BorderLayout(); //
BorderLayout(int horp,verp); //
//
. , .
add() :
add(int poz, Component comp);
poz , , (North, South, East, West Center).
CardLayout ( ). , ( ). , . , , . , .
GridBagLayout ( ). , . , GridLayout. , . , . . ֳ ᒺ GridBagConstraints, :
gridx, gridy , . gridx = gridy = GridBagConstraint.RELATIVE, gridx , gridy ;
gridwidth, gridheight , . 1. gridwidth = GridBagConstraint.REMAINDER gridheight = GridBagConstraint. EMAINDER, ( ). , GridBagConstraint.RELATIVE; fill , , , . ³ :
GridBagConstraint.NONE ( ) ;
GridBagConstraint.HORIZONTAL ,
GridBagConstraint.VERTICAL ,
GridBagConstraint.BOTH ;
ipadx, ipady , ( 0);
insets Insets , ( ), , , ;
anchor .
:
GridBagConstraint.NTER ( ), GridBagConstraint.NORTH, GridBagConstraint.NORTHEAST,GridBagConstraint.EAST, GridBagConstraint.SOUTHEAST, GridBagConstraint.SOUTH, GridBagConstraint.SOUTHWEST,
GridBagConstraint.WEST, GridBagConstraint.NORTHWEST;
