esercitazione sulla calcolatrice

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Calcolatrice {
JFrame f=new JFrame("Calcolatrice");
JLabel l1=new JLabel("1° operando");
JLabel l2=new JLabel("2° operando");
JLabel l3=new JLabel("risultato : ");
JTextField f1=new JTextField();
JTextField f2=new JTextField();
JButton b1=new JButton("+");
JButton b2=new JButton("-");
JButton b3=new JButton("x");
JButton b4=new JButton("/");
JButton b5=new JButton("clear");
JButton b6=new JButton("=");
JLabel risultato=new JLabel();
JPanel p1=new JPanel();
JPanel p2=new JPanel();
char valori;


public Calcolatrice(){
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(500,500);
p1.setLayout(new GridLayout(3,2));
p2.setLayout(new GridLayout(2,3));
p1.add(l1);
p1.add(f1);
p1.add(f2);
p1.add(l2);
p1.add(l3);
p1.add(risultato);
p2.add(b1);
p2.add(b2);
p2.add(b4);
p2.add(b3);
p2.add(b5);
p2.add(b6);
f.add (BorderLayout.NORTH,p1);
f.add (BorderLayout.CENTER,p2);

b1.addActionListener(new Addizione());
f.setVisible(true);
b2.addActionListener(new Sottrazione());
f.setVisible(true);
b3.addActionListener(new Moltiplicazione());
f.setVisible(true);
b4.addActionListener(new Divisione());
f.setVisible(true);
b5.addActionListener(new Clear());
f.setVisible(true);
b6.addActionListener(new Uguale());
f.setVisible(true);

}


public class Addizione implements ActionListener{
public void actionPerformed(ActionEvent event){
String testo1=f1.getText();
String testo2=f2.getText();
int t=Integer.parseInt(testo1);
int t1=Integer.parseInt(testo2);
double addizione=t+t1;
String r=Double.toString(addizione);
risultato.setText(r);
}
}

public class Sottrazione implements ActionListener{
public void actionPerformed(ActionEvent e){
String testo1=f1.getText();
String testo2=f2.getText();
int t=Integer.parseInt(testo1);
int t1=Integer.parseInt(testo2);
double sottrazione=t-t1;
String r=Double.toString(sottrazione);
risultato.setText(r);
}
}
public class Moltiplicazione implements ActionListener{
public void actionPerformed(ActionEvent e){
String testo1=f1.getText();
String testo2=f2.getText();
int t=Integer.parseInt(testo1);
int t1=Integer.parseInt(testo2);
int moltiplicazione=t*t1;
String r=Integer.toString(moltiplicazione);
risultato.setText(r);
}
}
public class Divisione implements ActionListener{
public void actionPerformed(ActionEvent e){
String testo1=f1.getText();
String testo2=f2.getText();
int t=Integer.parseInt(testo1);
int t1=Integer.parseInt(testo2);
double divisione=t/t1;
String r=Double.toString(divisione);
risultato.setText(r);
}
}
public class Uguale implements ActionListener{
public void actionPerformed(ActionEvent event){
String testo1=f1.getText();
String testo2=f2.getText();
int t=Integer.parseInt(testo1);
int t1=Integer.parseInt(testo2);
double r=0;
if(valori=='+') r=t+t1;
if(valori=='-') r=t-t1;
if(valori=='X') r=t*t1;
if(valori=='/') r=t/t1;
String rr=Double.toString(r);
risultato.setText(rr);

}
}
public class Clear implements ActionListener{
public void actionPerformed(ActionEvent e){
f1.setText("");
f2.setText("");
risultato.setText("");
}
}
public static void main (String []args){
Calcolatrice f=new Calcolatrice();
}
}

Ecco l'albero di natale con le lucine

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class AlberoNatale {private JFrame albero;
private PannelloAlbero a;
private JButton accende;
private JButton spegne;
private JPanel pannelloBottoni=new JPanel(new GridLayout(2,1));
private java.util.Timer pallineAccese;
public AlberoNatale(){albero=new JFrame("Albero del Santo Natale 2008");
albero.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
albero.setSize(500,500);
a=new PannelloAlbero();
accende=new JButton("accendi le lampadine");
spegne=new JButton("spegni le lampadine");
pannelloBottoni.add(accende);
pannelloBottoni.add(spegne);
albero.add(a,BorderLayout.CENTER);
albero.add(pannelloBottoni,BorderLayout.SOUTH);
accende.addActionListener(new BottoneAccende());
spegne.addActionListener(new BottoneSpegne());
albero.setVisible(true);
}public class PannelloAlbero extends JPanel{
public void paintComponent(Graphics g){
Graphics g2d=(Graphics2D) g;
Image alberoImmagine=new ImageIcon("AlberoNatale[1].jpg").getImage();
g.drawImage(alberoImmagine,0,0,albero.getWidth(),albero.getHeight(),null);
g.setColor(getColore());
g.fillOval(200,200,30,30);
g.setColor(getColore());
g.fillOval(300,200,30,30);
g.setColor(getColore());
g.fillOval(150,300,30,30);
g.setColor(getColore());
g.fillOval(250,250,30,30);
g.setColor(getColore());
g.fillOval(350,300,30,30);

}
}
private Color getColore(){
int verde=(int) (Math.random()*255);
int rosso=(int) (Math.random()*255);
int blu=(int) (Math.random()*255);
Color colore=new Color(rosso,verde,blu);
return colore;
}

public class BottoneAccende implements ActionListener{
public void actionPerformed(ActionEvent event){
pallineAccese=new java.util.Timer();
pallineAccese.schedule(new TimerTask(){
public void run(){
SwingUtilities.invokeLater(new Runnable(){
public void run(){
albero.repaint();
}
});
}
},0,200);
}
}

public class BottoneSpegne implements ActionListener{
public void actionPerformed(ActionEvent event){
pallineAccese.cancel();
}
}
public static void main(String[] args){
AlberoNatale albero=new AlberoNatale();

}

}

Programma rotazione poligono

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;
import java.awt.geom.*;
import java.awt.Polygon;
public class RotazionePoligonno extends Applet implements MouseListener {
    private int[] xpoints ={0,-10,-7,7,10};
    private int[] ypoints ={-10,-2,10,10,-2};
    private Polygon poly;
  
    int rotation=0;
    public void init(){
         poly=new Polygon(xpoints,ypoints,xpoints.length);
         addMouseListener(this);
        }
       
    public void paint (Graphics g){
    Graphics2D g2D= (Graphics2D) g;
    int ampiezza=getSize().width;
    int altezza=getSize().height;


    g2D.translate(ampiezza/2,altezza/2);
    g2D.scale(20,20);
    g2D.rotate(Math.toRadians(rotation));
    g2D.setColor(Color.RED);
    g2D.draw(poly);
   
    }
    public void mouseEntered (MouseEvent m) {}
    public void mouseExited (MouseEvent m) {}
    public void mouseReleased (MouseEvent m) {}
    public void mouseClicked (MouseEvent m) {}
    public void mousePressed(MouseEvent m) {
        switch (m.getButton() ){
            case MouseEvent.BUTTON1:
            rotation--;
            if (rotation<0)   rotation=359;
            repaint ();
            break;
            case MouseEvent.BUTTON3:
            rotation++;
            if (rotation<360)   rotation=0;
            repaint ();
            break;
        }
    }

     public void keyReleased(KeyEvent k){}
     public void keyTyped(KeyEvent k){}
     public void keyPressed(KeyEvent k){
    
        switch (k.getKeyCode()) {
            case KeyEvent.VK_LEFT:
            rotation--;
            if (rotation<0) rotation=359;
            repaint();
            break;
        case KeyEvent.VK_RIGHT:
        rotation++;
        if (rotation>360) rotation=0;
        repaint();
        break;
      
      }
    }      
}

Implementazioni delle classi nel linguagio java

classe telvisore
{
private String marca;
public int dimensioni;
public char colore;
}

classe cellulare
{
private String disposizione tasti;
public String sfondo;
}

classe gatto
{
public int eta;
public char sesso;
public char tipo pelo;
}

classe rivista
{
public char tipo carta utilizzata;
public String periodicità;
}

classe penna
{
public char tipo colore;
private String marca;
}

implementazione del gochino

int baoard[29];
int i;
char caratteri[3] (" ","","+");

main(){

Void azzeraBoard(board[29]) {
int i;

for(i=1;j<8;i++);

board[i]=1;

for(i=9;j<14;i++);

board[i]=9;

for(i=17;j<24;i++);

board[i]=17;
}

void stampa(){

for(i=1;i>29;i++);

printf("%c",caratteri[array[i]]);
}