Thread: how to read URL

Hi everybody
i am a beginner in java programming,
i want to read from url (which read a temperature from a website and then print it on screen, now subclass is:

import java.net.*;
import java.io.*;
public class NetworkTemperatureSensor extends TemperaturSensor{
    NetworkTemperatureSensor(String sid)
    {
        super(sid);
    }
 
    public Temperature read(){
        Temperature t1 = new Temperature();
 
                try
		{       
                        URL url = new URL("http://www.temperatur.nu/termo/boras/temp.txt");
			URLConnection conn = url.openConnection();
			InputStream uc = conn.getInputStream();   
			BufferedReader buffIn = new BufferedReader(new InputStreamReader(uc));
                        String s;   
                    while((s = buffIn.readLine())!= null)
			{
                            System.out.println(s);   
			}
                        buffIn.close();
                        t1.setKelvin(Double.parseDouble(s));
 
		}
		catch (Exception e)
		{
			System.out.println("Exception "+e);
		}
 
	return t1;
}
}

into the main method :

 
 
import java.util.*;
import java.util.ArrayList;
 
public class DataLoggerApplikation {
 
 public static void main(String[] args) {
 
     //private Temperature bb;    
     DataLoggerApplikation app = new DataLoggerApplikation();
     Temperature bb = new Temperature();
     app.initiering();
     for(int i = 0; i < 5; i++)
     {
         app.logSensorValues();
     }
     app.skriva();
     bb.equals(bb);
 
 
    }
 
 ArrayList<Sensor> sensorer;
 
 
 public void initiering()
 {
 
    sensorer = new ArrayList();
    sensorer.add(new TemperaturSensor("ts"));
    sensorer.add(new FakeTemperatureSensor("fts"));
    sensorer.add(new FakeTemperatureSensor("fts2"));
 }
 
 
public void logSensorValues()
{
 
    Iterator itr = sensorer.iterator();
    Sensor s;
    while(itr.hasNext())
        {
            s = (Sensor) itr.next();
            s.datalogger.add(s.read());
        }
}
 
public void skriva()
{
    Iterator itr = sensorer.iterator();
    Sensor s;
        while(itr.hasNext())
        {
            s = (Sensor)itr.next();
            s.skrivaVarde();
        }
}
 
}

when i execute program , it shows nothing about url and reading Temp online, because this has not been defined into main method to show something, this program contain many classes but here just come main method and one subclass, i dot know how to take temperature from subclass to main mathod :

public class NetworkTemperatureSensor extends TemperaturSensor{
.
.
.
}

the whole subclass code is in post #1

should i define any variable in main method?

Norm, i think i couldnt explain what i mean exactly. could u please do me favor , Can i zip all the file and send it to you, if u run the code once, u will get what mean.

look post #1 for code, here is result from execution of program:

Values of Sensor(ts)
10.0 Kelvin
10.0 Kelvin
10.0 Kelvin
10.0 Kelvin
10.0 Kelvin
-------------------------

Values of Sensor(fts)
-7.0 Kelvin
47.0 Kelvin
-43.0 Kelvin
-26.0 Kelvin
-25.0 Kelvin
-------------------------

Values of Sensor(fts2)
-17.0 Kelvin
-10.0 Kelvin
-29.0 Kelvin
28.0 Kelvin
-27.0 Kelvin
-------------------------

as told before, it shows nothing about taking temp from a url ,website. please just show me how to define it into main method to print out online temperature

I'm confused about what you want.

The main method should call the reading method and then return data for processing, surely?
Your code seems overly complex for what it seems to be designed to do.

The data is reading successfully, so you need to decide where it goes from there.

question wants to get value by user and get the value from website, the first part (value by user) works good but problem is how to call that subclass in main method to be readable, i have tried to get temperature online by using NetworkTemperatureSensor subclass and then read the value and display in on screen. but here i want the program to get temperature from the url (website) 5 times and add it to a list which i created a Arraylist<...> sensorer , then i wrote it like this:

sensorer.add(new NetworkTemperatureSensor("nts"));

when i execute this code, that just give me this Exception error:

-2.8
Exception in thread "main" java.lang.NullPointerException
at sun.misc.FloatingDecimal.readJavaFormatString(Floa tingDecimal.java:1008)
at java.lang.Double.parseDouble(Double.java:540)
at NetworkTemperatureSensor.read(NetworkTemperatureSe nsor.java:24)
at NetworkTemperatureSensor.read(NetworkTemperatureSe nsor.java:3)
at DataLoggerApplikation.logSensorValues(DataLoggerAp plikation.java:46)
at DataLoggerApplikation.main(DataLoggerApplikation.j ava:15)
Java Result: 1

this program have 10 classes, but here i just posted 2 class that cause that problem!!!!