non static varible from static context error

in this class i have a constructor and a main() function for testing the constructor
theres a couple things stopping me from testing it in the command prompt tho
the post data is a string with an ampersand in it and when i try to pass it to the main function in the command prompt it thinks that the ampersand means something, i dont know how to "escape" it
also, i would like to know how to pass a value from the constructor to main() so i can print string test, i tried putting it outside both meathods into the class but it gave me non static context error

Code :

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//takes am address, and post data, and returns the html as a string
import java.net.*;
import java.io.*;
import java.lang.*;
public class UrlToString
{
	public String test = "";
	public static void main (String[] args) throws Exception
	{
		//enter url and post data in cmd prompt to test
		new UrlToString  (test,args[0],args[1]);
		System.out.println(test);
	}
	//paramaters of returned string, address to get it from, and post data in th for of variable1=value1&variable2=value2...
	UrlToString (String returnString, String inAddr, String rawData) throws Exception
	{
		returnString = "";
		//connection variables
		String agent = "Mozilla/4.0";
		String type = "application/x-www-form-urlencoded";
		HttpURLConnection connection = null;
		String encodedData = URLEncoder.encode( rawData, "UTF-8");
		//connect
		try 
		{
			URL searchUrl = new URL(inAddr);
			connection = (HttpURLConnection)searchUrl.openConnection();
			connection.setDoOutput(true);
			connection.setRequestMethod("POST");
			connection.setRequestProperty( "User-Agent", agent );
			connection.setRequestProperty( "Content-Type", type );
			connection.setRequestProperty( "Content-Length", Integer.toString(encodedData.length()) );
			OutputStream os = connection.getOutputStream();
			os.write( encodedData.getBytes() );
			os.flush();
			os.close();
			//check if theres an http error
			int rc = connection.getResponseCode();
			if(rc==200)
			{
				//no http response code error
				//read the result from the server
 
				InputStreamReader in = new InputStreamReader(connection.getInputStream());
				BufferedReader br = new BufferedReader(in);
				String strLine;
				//Read File Line By Line
				while ((strLine = br.readLine()) != null)
				{
					returnString = returnString.concat(strLine);
					System.out.println(strLine);
				}
				return;
			}
			else
			{
				System.out.println("http response code error: "+rc+"\n");
				return;
			}
 
		}
		catch( IOException e )
		{
			System.out.println("search URL connect failed: " + e.getMessage());
			e.printStackTrace();
		}
	}
}

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It means that you're calling a non-static variable in a static method.

For starters, try making the variable test be static.

A non-static variable only exists as part of an instance of a class. When you create a class object, all its non-static variables are created with it. Each class object has its own version of each non-static variable.
A static variable is shared by all instances of a class. There is only one version of that variable.

Why is test a class variable instead of a local variable in the main() method?

Quote:

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Originally Posted by Norm

A non-static variable only exists as part of an instance of a class. When you create a class object, all its non-static variables are created with it. Each class object has its own version of each non-static variable.
A static variable is shared by all instances of a class. There is only one version of that variable.

Why is test a class variable instead of a local variable in the main() method?

---

It would also work in the main method too.

It would be better there, but I was assuming that the OP had a reason for not having the variable in the main method.

Quote:

---

Originally Posted by Norm

A non-static variable only exists as part of an instance of a class. When you create a class object, all its non-static variables are created with it. Each class object has its own version of each non-static variable.
A static variable is shared by all instances of a class. There is only one version of that variable.

Why is test a class variable instead of a local variable in the main() method?

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because if i put it in main() it would pass to the constructor as local value not reference and would not change, i want test to be changed by the constructor and then go back to main after the constructor call, and then print it

If you want the main() method to be able to reference a class variable, you need to save a reference to the created instance of the class and use that to access its variables. The posted code does NOT save a reference to the instance when it uses new to create the instance. Save the reference in a variable and use that variable to access the test variable.

omfg ur right holy fuck im dumb
ok but still, its confusing, how i get rid of this error?
if i make the variable static i cant change it

Quote:

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how i get rid of this error?

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See post #6

wait nm i got it im dumb i nedded to pass it an empty strin, chich sems kind of wierd

Please post the full text of the error message.

i got it
sorry for the dumb questions lol i just have been doing alot of procedurally oriented programming lately not much object oreinted
i still dont know how to pass an ampersand as part of a string to a class in the command line tho, i need to escape it or something

Sorry, I don't know much about how you are trying to make the OS do something.

That ampersand thing, I'm not sure exactly what you mean, but you don't mean a reference do you? That's C++, not Java. C is procedure oriented. C++ is object oriented.

However, perhaps C also has pass by reference params, and I think it does actually. I know it allows you to pass pointers. (I know it does for C-Strings.)

Java isn't that great for messing with the operating system at the lower levels. C++ would be better, as it has C and allows procedure oriented as well as OO.

If you're talking about C++ passing &, then I don't think it would be any different, at least param wise, as passing a regular param.