Esercizio

public class ContoCorrente{
int saldo;
int numeroConto;
public ContoCorrente(int saldo,int numeroConto){
this.saldo=saldo;
this.numeroConto=numeroConto;
}

public int getSaldo(){
return saldo;
}
public void prelievo(int p){
saldo=saldo-p;
if (saldo<0){
saldo=0;
}
}

public void versamento(int v){
saldo=saldo+v;
}

public int getNumeroConto(){
return numeroConto;
}
}

--------------------------------------------------------------------------------------------------

public class TestaConto{
public static void main(String[] args){
ContoCorrente c1=new ContoCorrente(1000,1);
System.out.println(c1.getSaldo());
ContoCorrente c2=new ContoCorrente(100,2);
c1.versamento(500);
System.out.println(c1.getSaldo());
c1.prelievo(2000);
System.out.println(c1.getSaldo());
ContoCorrente[] conti=new ContoCorrente[2];
conti[0]=c1;
conti[1]=c2;
for (int i=0; i++; i<2){
System.out.println(conti[i].getSaldo());
}
}
}

Rotazione Poligono

import java.awt.*; /*abstract windows toolkit*/
import java.awt.event.*;
import java.applet.*;
import java.util.*;
import java.awt.geom.*;

public class RotazionePoligono extends Applet implements MouseListener, KeyListener {
private int[] xpoints= {0,-10,-7,7,10};
private int[] ypoints= {-10,-2,10,10,-2};

private Polygon poly; /*creo un nuovo poligono*/
int rotation=0;
public void init() { /*primo metodo che viene lanciato quando l'applet viene creata*/
poly=new Polygon(xpoints,ypoints,xpoints.length);
addMouseListener(this);
addKeListener(this);
}
public void paint(Graphics g) {
Graphics2D g2d= (Graphics2D) g; /*converto una variabile (oggetto) g in una variabile (oggetto) g2d [CASTING]*/
int ampiezza=getSize().width;
int altezza=getSize().height;
g2d.setColor(Color.BLACK);
g2d.fillRect(0,0,ampiezza,altezza); /*riempe il rettangolo (Rect) per le coordinate fornite che lo delimitano
0,0 = limiti di partenza da cui iniziare a riempire
ampiezza,altezza = limiti di arrivo dove finire di riempire*/

g2d.translate(ampiezza/2,altezza/2);
g2d.scale(20,20);
g2d.rotate( Math.toRadians(rotation) );
/*istruzioni per disegnare il poligono*/
g2d.setColor(Color.YELLOW);
g2d.draw(poly);
g2d.setColor(Color.PINK);
g2d.fill(poly); /*riempo (con fill) la forma poligono (instanziata prima) con il colore settato da setColor*/

}
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 keyTiped(keyEvent k){}
public void keyPressed(keyEvent k){}

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

Esercizi

Prima Applet Java

import java.awt.*;
import java.applet.*;
public class PrimaApplet extends Applet {
public void paint(Graphics g){
g.drawString("Benvenuti gli studenti della classe IV",20,30);
}
}

Seconda Applet Java

import java.awt.*;
import java.applet.*;
public class SecondaApplet extends Applet {
public void paint(Graphics g){
Graphics2D g2d= (Graphics2D) g;
Rectangle r=new Rectangle(10,10,50,20);
g2d.draw(r);
}
}

Terza Applet Java

import java.awt.*;
import java.applet.*;
import java.util.*;

public class TerzaApplet extends Applet {
private Shape shape;
public void init(){
shape= new Rectangle2D.Double(-1.0,-1.0,1.0,1.0);
}
public void paint(Graphics g){
Graphics2D g2d= (Graphics2D) g;
g2d.setColor(Color.BLACK);
int width=getSize().width;
int height=getSize().height;
g2d.fillRect(0,0,width,height);
Rectangle r=new Rectangle(10,10,50,20);
g2d.draw(r);
}
}

Applet 1

< html >
< head >< title >prima applet< /title >< /head >
< body >
< applet codebase="." code="PrimaApplet.class" name="Prima Applet" width="300" height="500" >< /applet >
< /body >
< /html >


Applet 2

< html >
< head >< title >prima applet< /title >< /head >
< body >
< applet codebase="." code="SecondaApplet.class" name="Seconda Applet" width="300" height="500" >< /applet >
< /body >
< /html >