LEGGERE DA TASTIERA

BufferedReader console = new BufferedReader ( lettore )    // import java.io.BufferedReader

ConsoleReader console = new ConsoleReader ( System.in )

- readInt()

- readDouble()

- readLine()

String input = console.nextLine()

StringTokenizer word = new StringTokenizer ( input ) // import java.util.StringTokenizer

while (word.hasMoreToken () )

Scanner in = new Scanner ( System.in ) // import java.util.Scanner

- nextInt()

- nextDouble()

- nextLine()

- next()

- hasNext()

- hasNextInt()

- hasNextDouble()

STRING // import java.lang.String

- charAt ( posizione )

- length()

- toUpperCase()

- toLowerCase()

- subString( da, a ) / ( da )

- trim() // elimina spazi

- concat ( String )

- replace ( questiCaratteri, conQuestiAltri)

SUDDIVISIONE DI STRINGHE // import java.util.StringTokenizer

StringTokenizer tokenizer = new StringTokenizer ( " stringa " / console.readLine() )

- hasMoreToken ()

- nextToken ()

CHARACTER // import java.lang.Character

Character.isUpperCase( char )

.isLowerCase ( char )

.isLetter ( char )

.isDigit ( char )

STRING <--> INTEGER // java.lang.Integer / Double

int n = Integer.parseInt ( Stringa )

double n = Double.parseDouble ( Stringa )

String str = Integer.toString ( n )

SCRITTURA FILE

File doc = new File ( nomeDelFile ) // import java.io.File

- delete()

- renameTo ( refernceAdUnOggetoFile )

FileOutputStream out = new OutputStream ( doc ) // import java.io.FileOutputStream

PrintStream output = new PrintStream ( out ) // import java.io.PrintStream

PrintStream output = new PrintStream ( new FileOutputStream ( new File ( nomeFile ) ) )

- print ( stringa )

- println ( stringa )

- printf ( stringaFormatted , oggetti stringa )

//OPPURE

PrintWriter output = new PrintWriter ( "nomefile" ) // import java.io.PrintWriter

-print...

N.B

nomefile.close()

LETTURA FILE

FileInputStrem inp = new FileInputStream ( doc ) // import java.io.FileInputStream

InputStreamReader ( inp ) // import java.io.InputStreamReader

BufferedReader input = new BufferedReader ( inp ) // import java.io.BufferedReader

- readLine()

N.B

nomefile.close()

FINESTRE DI DIALOGO // import javax.swing.JOPtionPane

String input = JOPtionPane.ShowInputDialog ( prompt )

JOPtionPane.showMessageDialog ("Testo")

System.exit (0)

FORMATTAZIONE NUMERI // import java.text.NumberFormat

NumberFormat formatter = NumberFormat.getNumberIstance()

formatter.setMaximumFractionDigit ( int n )

formatter.setMinimumFractionDigit ( int n )

Double dato

dato = formatter.format ( dato )

GENERATORE NUMERI // import java.util.Random

import java.util.Random

Random generatore = new Random();

generatore.nextInt ( n ); // 0 <= x < n

generatore.nextDouble ();   // 0 <= x < 1

CONFRONTI

tra numeri in virgola mobile

final Double EPSILON = 1E-14;

if ( Math.abs ( x - y ) <= EPSILON )

// x è approssimativamente vicino a y

tra stringhe

String input

input == "y" // verifica l'identità dei riferimenti

input.equals("y)    // verifica l'identità delle stringhe

input.equals.IgnoreCase("y")

input.compareTo("y") < 0 (> = ) // verifica se input precede o segue "y" lessicograficamente

tra oggetti

// verifica identità riferimenti e il null

.equals(obj) // verifica identità oggetti, deve essere definita per la classe che lo usa

LISTA A PUNTATORI

class Node

Node link;

Object data;

Node list = new Node ( x, null );

list = new Node ( y, list );

list = new Node ( z, list );

CONTARE ITERAZIONI

for ( i = a; i < b; i++)

incremento = 1

- limiti asimmetrici n = b - a;

- limiti simmetrici n = b - a +1;

incremento > 1

- limiti asimmetrici n = b - a / c;

- limiti simmetrici n = b - a / c + 1

CLASSI INVOLUCRO

Byte, Boolean, Character, Double, Float, Integer, Long, Short

(versione java5.0)   (versioni precedenti)

Double d = 29.95  Double d = new Double ( 29.95 ) // WRAPPING

double x = d double x = d.doubleValue () // UNBOXING

FRAME // import javax.swing

JFrame frame = new JFrame()

- setSize ( pixel, pixel)

- setTitle ( String )

- setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE )

- setVisible ( true )

- pack()

- add ( component )

- setJMenuBar ( menuBar )

COMPONENTI GRAFICI // import

public class nuovoComponente extends JComponent

colore

g2.setColor ( Color.X )

g2.setColor ( 1.0F-0.0F(rosso), verde, blu)

g2.draw( disegno )

g2.fill ( disegno )

Color.BLACK

.BLUE

.CYAN

.GRAY

.GREEN

.ORANGE

.PINK

.RED

.WHITE

.YELLOW

rettangoli // import java.awt.Rectangle

new Rectangle (x, y, width, heigth)

- translate(x, y)

ellissi // import java.awt.geom.Elipse2D

new Ellipse2D.Double ( x, y, width, height )

segmenti // import java.awt.geom.Line2D

new Line2D.Double ( x1, y1, x2, y2)

new Line2D.Double ( Point2D, Point2D )

punti // import java.awt.geom.Point2D

new Point2D.Double ( x1, y1)

APPLET // import javax.swing.JApplet

public class MyApplet extends JApplet

NB vantaggio: nn richiede frame e componenti, si può visualizzare in un browser

visualizzazione applet in file.html

<applet code= "nomeMioApplet.class" width = "300" heigth="300">

</applet>

<html>

<head>

<title>inserirequiilnomedellapagina</title>

</head>

<body>

<p>inserirequiilnomedelmioapplet</p>

<applet code="nomeMioApplet.class" width="300" heigth="300" >

</applet>

<body>

</html>

TEMPORIZZATORE // import javax.swing.Timer

class MioRicavitore implements ActionListener

MioRicevitore listener new MioRicevitore()

Timer t = new Timer ( interval, listener);

t.start();

INTERFACCIA UTENTE

pulsanti

JButton button = new JButton ( String )

- addActionListener ( listener )

- isSelected ()

// mutuamente esclusivi

JRadioButton button = new JRadioButton ( String )

ButtonGroup group = new ButtonGroup()

group.add ( button )

// non esclusivi

JCheckBox casellaDiControllo = new JCheckBox ( String )

// molte scelte mutuamente esclusive

JComboBox caselleCombinata = new JComboBox ()

- addItem ( String )

- setEditable ()

- getSelectedItem ()

label

JLabel label = new JLabel ( String )

- setText ( String )

immagini

ImageIcon immagine = new ImageIcon(nomefileimmagine)

pannelli

JPanel panel = new JPanel()

-add ( componente )

-setLayout ( layout manager )

-setBorder ( new EtchedBorder () )

-setBorder ( new TitledBorder ( new EtchedBorder (), " Titolo ")

campi di testo

JTextField campo = new JTextField ( numero caratteri )

- getText

JTextArea textArea = new JTextArea ( rows, columns )

- setEdotable ( boolean )

JScrollPane barreDiScorrimento = new JScrollPane ( textArea )

textArea.setContentPane( barreDiScorrimento )

layout manager

panel.setLayout ( new FlowLayout() )

BorderLayout()

panel.add ( component , BorderLayout.NORTH

WEST

CENTER

EAST

SOUTH

new GridLayout( nRighe, nColonne)

EVENTI DEL MOUSE

public interface MouseListener

component.addMouseListener ()

event.getX()

event.getY()

public interface MouseAdapter

EXCEPTIONS

ClassNotFoundException

Thrown when an application tries to load in a class

through its string name using:

- the forName method in class Class

- the findSystemClass method in class ClassLoader

- the loadClass method in class ClassLoader

but no definition for the class with the specified name

could be found.

CloneNotSuportedException

Thrown to indicate that the clone method in class Object

has been called to clone an object, but that the object's

class does not implement the Cloneable interface.

DataFormatException

Signals that a data format error has occurred

IOException

EOFException

Signals that an end of file or end of stream has been

reached unexpectedly during input

FIleNotFoundException

Signals that an attempt to open the file denoted by

a specified pathneme has failed

RuntimeException

ArithmeticException

Thrown when an exceptional arithmetic condition

has occurre.For example, an integer "divide by zero"

ArrayStoreException

Thrown to indicate that an attempt has been made to

store the wrong type of object into an array of objects

Object x [ ] = new String [ 3 ];

x [ 0 ] = new Integer ( 0 );

ClassCastException

Thrown to indicate that the code has attempted to cast

an object to a subclass ofwhich it is not an istance.

Object x = new Integer ( 0 );

System.out.println ( ( String ) x ) ;

IllegalArgumentException

Thrown to indicate that a method has passed an illegal

or inappropriate argument

NumberFormatException

IllegalFormatException

IllegalStateException

Signals that a method has been invoked at an illegal

or inappropriate time. In other words, the Java

environment or Java application is not in an appropriate

state for the requested operation.

IndexOutBoundsException

Thrown to indicate that an index of some sort ( such as

to an array, to string, or to a vector )is out of range.

NullPointerException

Thrown when an application attemps to use null in a case

where an object is required. These include:

- Calling the instance method of a null object

- Accessing or modifing the field of a null object

- Taking the length of null as if it were an array

- Throwing null as if it were a Throwable value

Aplications should throw instance of this class to indicate

other illegal uses of the null object