Lösungsvorschläge - Technische Universität München
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TECHNISCHE
UNIVERSITÄT
MÜNCHEN
FAKULTÄT FÜR INFORMATIK
Praktikum Grundlagen der Programmierung
Lösungsvorschläge zu Blatt 10
Robert Eigner, Florian Forster
SS 2010
05.07.2010
Praktikum Grundlagen der Programmierung
Aufgabe 48 Mondrian (Lösungsvorschlag)
package de . tum . in . pgdpSS2010 . blatt10 . aufgabe48 ;
import java . applet . Applet ;
import java . awt . Color ;
import java . awt . Graphics ;
import java . awt . event . MouseEvent ;
import java . awt . event . MouseListener ;
import java . util . Random ;
public class Mondrian extends Applet implements MouseListener {
private static final long serialVersionUID = 1L;
private Random rand = new Random ();
private int i = 0;
public void init () {
setSize (600 , 800);
addMouseListener (this);
}
public void paint ( Graphics g ){
Color [] colors = new Color [3];
colors [0] = Color . RED ;
colors [1] = Color . BLUE ;
colors [2] = Color . YELLOW ;
g. fillRect (0 , 0, 10 , 800);
g. fillRect (150 , 0, 10 , 800);
g. fillRect (450 , 600 , 10 , 200);
g. fillRect (590 , 0, 10 , 800);
g. fillRect (0 , 0, 600 , 10);
g. fillRect (0 , 200 , 150 , 20);
g. fillRect (0 , 600 , 600 , 10);
g. fillRect (450 , 700 , 150 , 10);
Lösung 10/ Seite 2
g. fillRect (0 , 790 , 600 , 10);
g. setColor ( colors [i ]);
g. fillRect (160 , 10 , 430 , 590);
i ++;
i=i %3;
g. setColor ( colors [i ]);
g. fillRect (10 , 610 , 140 , 180);
i ++;
i=i %3;
g. setColor ( colors [i ]);
g. fillRect (460 , 710 , 130 , 80);
}
public void mouseClicked ( MouseEvent arg0 ) {
if( arg0 . getButton () == MouseEvent . BUTTON1 ) {
i = rand . nextInt (3);
repaint ();
}
}
public
public
public
public
void
void
void
void
mouseEntered ( MouseEvent arg0 ) {}
mouseExited ( MouseEvent arg0 ) {}
mousePressed ( MouseEvent arg0 ) {}
mouseReleased ( MouseEvent arg0 ) {}
}
Der Quelltext der dazugehörenden HTML-Seite lautet:
<! DOCTYPE HTML PUBLIC " -// W3C // DTD HTML 4.01 Transitional // EN "
" http :// www . w3 . org / TR / html4 / loose . dtd " >
<html >
<head >
<title > Mondrian als Java - Applet </ title >
</ head >
<body >
<h1 > Ein & quot ; Mondrian - Bild - Generator & quot ; </h1 >
<p > Klicken Sie ins Bild , um die Farben zu & auml ; ndern </p >
<p >
< applet code =" Mondrian . class " width =" 600 " height =" 800 "
alt =" Ein & quot ; Mondrian - Bild - Generator & quot ;" ></ applet >
</p >
</ body >
</ html >
Aufgabe 49 Fotoalbum (Lösungsvorschlag)
import
import
import
import
java . awt . BorderLayout ;
java . awt . GridBagLayout ;
java . io . File ;
java . io . FileFilter ;
Lösung 10/ Seite 3
import
import
import
import
import
import
import
javax . swing . ImageIcon ;
javax . swing . JButton ;
javax . swing . JFileChooser ;
javax . swing . JFrame ;
javax . swing . JLabel ;
javax . swing . JPanel ;
javax . swing . JScrollPane ;
public class FotoAlbum extends JFrame {
private
private
private
private
private
private
private
private
private
private
private
private
private
static final long serialVersionUID = 1L;
JPanel jContentPane = null;
JButton okButton = null;
JButton previousButton = null;
JButton nextButton = null;
JScrollPane scrollPane = null;
JFileChooser chooser = new JFileChooser ();
File dir ;
File files [] = null;
int i = 0;
JLabel imageLabel ;
JLabel textLabel ;
ImageIcon images [] = null;
public FotoAlbum () {
super();
initialize ();
}
private void initialize () {
this. setSize (900 , 700);
this. setContentPane ( getJContentPane ());
this. setTitle (" Fotoalbum " );
}
private JPanel getJContentPane () {
if ( jContentPane == null) {
jContentPane = new JPanel (new BorderLayout ());
JPanel jp = new JPanel ();
jp . add ( getOKButton ());
jContentPane . add (jp , BorderLayout . NORTH );
jp = new JPanel (new GridBagLayout ());
jp . add ( getPreviousButton ());
jContentPane . add (jp , BorderLayout . WEST );
jp = new JPanel (new GridBagLayout ());
jp . add ( getNextButton ());
jContentPane . add (jp , BorderLayout . EAST );
jp = new JPanel ();
getTextLabel (). setText (" Please select directory first !" );
jp . add ( getTextLabel ());
jContentPane . add (jp , BorderLayout . SOUTH );
jContentPane . add ( getJScrollPane ());
}
return jContentPane ;
Lösung 10/ Seite 4
}
private JButton getOKButton () {
if ( okButton == null) {
okButton = new JButton (" Open " );
okButton . addActionListener (new java . awt . event . ActionListener () {
public void actionPerformed ( java . awt . event . ActionEvent e) {
chooser . setCurrentDirectory (new java . io . File ("." ));
chooser . setFileSelectionMode ( JFileChooser . DIRECTORIES_ONLY );
chooser . setAcceptAllFileFilterUsed (false);
if ( chooser . showOpenDialog ( FotoAlbum .this) ==
JFileChooser . APPROVE_OPTION ) {
dir = chooser . getSelectedFile ();
files = dir . listFiles (new FileFilter () {
public boolean accept ( File file ) {
return ( file . getName ().
toLowerCase (). endsWith (". gif ") ||
file . getName ().
toLowerCase (). endsWith (". jpg ") ||
file . getName ().
toLowerCase (). endsWith (". png " ));
}
});
images = new ImageIcon [ files . length ];
for (int j = 0; j < files . length ; j ++) {
images [j] = new ImageIcon ( files [j ]. getAbsolutePath ());
images [j ]. setDescription ( files [j ]. getAbsolutePath ());
i = 0;
}
getTextLabel (). setText ( images [i ]. getDescription ());
getImageLabel (). setIcon ( images [i ]);
getJScrollPane (). getViewport (). add ( getImageLabel ());
}
}
});
}
return okButton ;
}
private JButton getPreviousButton () {
if ( previousButton == null) {
previousButton = new JButton (" previous " );
previousButton . addActionListener (new java . awt . event . ActionListener () {
public void actionPerformed ( java . awt . event . ActionEvent e) {
i - -;
if (i == -1)
i = images . length - 1;
getTextLabel (). setText ( images [i ]. getDescription ());
getImageLabel (). setIcon ( images [i ]);
getImageLabel (). repaint ();
}
});
}
Lösung 10/ Seite 5
return previousButton ;
}
private JButton getNextButton () {
if ( nextButton == null) {
nextButton = new JButton (" next " );
nextButton . addActionListener (new java . awt . event . ActionListener () {
public void actionPerformed ( java . awt . event . ActionEvent e) {
i ++;
i = i % files . length ;
getTextLabel (). setText ( images [i ]. getDescription ());
getImageLabel (). setIcon ( images [i ]);
getImageLabel (). repaint ();
}
});
}
return nextButton ;
}
private JScrollPane getJScrollPane () {
if ( scrollPane == null) {
scrollPane = new JScrollPane ();
}
return scrollPane ;
}
private JLabel getTextLabel () {
if ( textLabel == null) {
textLabel = new JLabel ();
}
return textLabel ;
}
private JLabel getImageLabel () {
if ( imageLabel == null) {
imageLabel = new JLabel ();
}
return imageLabel ;
}
}