error with MalformedURLException
https://stackoverflow.com/questions/10465376
-
06-06-2021 - |
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RussianQuestion
My friend asked me to post his question here, and there it is:
I have an issue with this... My code worked out just fine, and suddenly a bug appears. I have no idea whats wrong in it, maybe you guys can show me some obvious mistake with I am making.
That's the error communicate:
> Exception in thread "main" java.net.MalformedURLException: no
> protocol:
> at java.net.URL.<init>(URL.java:583)
> at java.net.URL.<init>(URL.java:480)
> at java.net.URL.<init>(URL.java:429)
> at pogoda.Okienko.getJPanel(Okienko.java:120)
> at pogoda.Okienko.getJContentPane(Okienko.java:101)
> at pogoda.Okienko.initialize(Okienko.java:59)
> at pogoda.Okienko.<init>(Okienko.java:49)
> at pogoda.Pogoda.main(Pogoda.java:119)
and this is my code:
package pogoda;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Rectangle;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public final class Okienko extends JFrame
{
public static final long serialVersionUID = 1L;
public JPanel jContentPane = null;
public JLabel jLabel = null;
public JLabel jLabel1 = null;
public JLabel LabelTemp = null;
public JLabel LabelOdczuwalna = null;
public JPanel jPanel = null;
public Okienko(double temperatura, double odczuwalna, String adres) throws MalformedURLException
{
super();
initialize(temperatura, odczuwalna, adres);
}
public void initialize(double temperatura, double odczuwalna, String adres) throws MalformedURLException
{
this.setLocation(350, 250);
this.setSize(350, 350);
this.setContentPane(getJContentPane(temperatura, odczuwalna,adres));
this.setTitle("Pogoda");
this.setResizable(false); // jesli damy na true bedziemy mogli zmienic rozmiar naszego okienka
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public JPanel getJContentPane(double temperatura, double odczuwalna, String adres) throws MalformedURLException
{
if (jContentPane == null)
{
LabelOdczuwalna = new JLabel();
LabelOdczuwalna.setBounds(new Rectangle(200, 50, 100, 20));
odczuwalna *=100;
int pomoc=(int) odczuwalna;
odczuwalna = ((double)pomoc)/100;
LabelOdczuwalna.setText("" + odczuwalna + " °C");
LabelTemp = new JLabel();
LabelTemp.setBounds(new Rectangle(200, 10, 100, 20));
temperatura *=100;
pomoc = (int)temperatura;
temperatura = ((double)pomoc)/100;
LabelTemp.setText("" + temperatura + " °C");
jLabel1 = new JLabel();
jLabel1.setBounds(new Rectangle(5, 50, 300, 20));
jLabel1.setText("Temperatura odczuwalna");
jLabel = new JLabel();
jLabel.setBounds(new Rectangle(5, 10, 300, 20));
jLabel.setText(" Aktualna temperatura ");
jContentPane = new JPanel();
jContentPane.setLayout(null);
jContentPane.add(jLabel, null);
jContentPane.add(jLabel1, null);
jContentPane.add(LabelTemp, null);
jContentPane.add(LabelOdczuwalna, null);
jContentPane.add(getJPanel(adres), null);
}
return jContentPane;
}
public JPanel getJPanel(String adres) throws MalformedURLException
{
if (jPanel == null)
{
jPanel = new JPanel();
jPanel.setLayout(new GridBagLayout());
jPanel.setBounds(new Rectangle(75, 100, 150, 150));
}
java.net.URL where = new URL(adres);
ImageIcon icon = new ImageIcon(where);
JLabel pomocnik = new JLabel();
pomocnik.setIcon(icon);
jPanel.add(pomocnik);
return jPanel;
}
}
package pogoda;
/**
*
* @author mateusz
*/
import com.sun.corba.se.impl.logging.OMGSystemException;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import java.net.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.io.*;
public class Pogoda
{
public int counter = 1;
public static String linia1 =
"<span class=\"twc-forecast-when twc-none\">Right Now</span>";
public static String linia11 =
"<img src=\""+
".+"+
"\" alt=";
public static String linia2 =
"<td class=\"twc-col-1 twc-forecast-temperature\"><strong>"+
"\\d+"+
"°F</strong></td>";
public static String linia3 =
"<td class=\"twc-col-1 twc-forecast-temperature-info\">Feels Like: <strong>"+
"\\d+"+
"°</strong>";
public static void main(String args[]) throws IOException
{
int temperatura =0;
int odczuwalna =0;
String adresObrazka="";
String help = "";
String linia = "";
URL strona = new URL("http://www.weather.com/weather/today/Wroclaw+Poland+PLXX0029");
URLConnection con = (URLConnection) strona.openConnection();
con.connect();
BufferedReader in = new BufferedReader(new InputStreamReader(strona.openStream()));
while((linia = in.readLine()) != null)
{
Pattern p = Pattern.compile(linia2);
Matcher m = p.matcher(linia);
if(m.find())
{
help = m.group().substring(55,m.group().length()-20);
temperatura = Integer.parseInt(help);
System.out.println(temperatura);
}
p = Pattern.compile(linia3);
m = p.matcher(linia);
if(m.find())
{
System.out.println("znaleziono odczuwalna");
help = m.group().substring(72,m.group().length()-14);
System.out.println(help);
odczuwalna=Integer.parseInt(help);
}
p = Pattern.compile(linia1);
m = p.matcher(linia);
if(m.find())
{
linia = in.readLine();
p = Pattern.compile(linia11);
m = p.matcher(linia);
if(m.find())
{
System.out.println("Pobrałem adres obrazka");
System.out.println(m.group().substring(10,m.group().length()-6));
adresObrazka = m.group().substring(10,m.group().length()-6);
}
}
}
double temperatura1 = temperatura;
double odczuwalna1 = odczuwalna;
odczuwalna1 = ((odczuwalna1-32)*5)/9;
temperatura1 = ((temperatura1-32)*5)/9;
System.out.println("Dane pobrane");
System.out.println("Temperatura " + temperatura1 + "\n Odczuwalna " + odczuwalna1 + "\n Adres obrazka " + adresObrazka);
Okienko o = new Okienko(temperatura1,odczuwalna1,adresObrazka);
o.setVisible(true);
o.jContentPane.setVisible(true);
}
}
Solution
From the looks of it the application does the following:
- Retrieve the contents of a specific web page
- Use regular expressions to retrieve specific data from the above web page
- One of the items extracted is a URL to an image
- The URL is never verified to be valid
- Occasionally the URL isn't valid and an MalformedURLException is thrown
As the scraped web page is external to the application there is no guarantee that the extracted URL exist, is valid, or is in the same place as it was the last week (regardless of how well the regular expressions are written). There is only one solution and that is to fail gracefully (perhaps show another image in these cases) and optionally notify the application maintainer to update the regular expressions and/or web page used to extract the information.
OTHER TIPS
I agree with @erikxiv (+1) but want to add something.
First, the image URL is not necessarily absolute, i.e. looks like a full URL e.g. http://host/path/img.jpg. It could be relative reference defined relatively to the base of the page, e.g. something like images/theimage.jpg. You have to detect this situation (for example using regular expression) and create full URL specification as string prior to calling constructor of URL.
And please do not take it as personal but your code contains a lot of hard coded constants you are using for string parsing. Even if it works for you now it is very fragile and can be broken and fail every time weather.com makes even very little changes in their site. I'd suggest you to use either regular expressions or, better on of widely available HTML parsers implemented in java.
And the last comment. You are using names in Polish in your code. I believe that this makes your code hardly to understand for guys that do not know Polish. It does not bother me too much as far as I know Russian but most of the guys here do not have this privilege.
Anyway good luck in your development and studies.
