How to check if a URL is accessible or not?

Programming Questions

fari

How to check if a URL is accessible or not?

in Programming Questions • 3 months ago

I am trying to read json from a URL, but when the link is not found, the sketch prints errors (though the program is not interrupted). How can I check if the URL is accessible or not? I am using the following code, but it doesn't work:

if (loadStrings(request)==null) {
println("Link broken");
}
else{
//do something
}

Replies(3)

PhiLho

Re: How to check if a URL is accessible or not?

3 months ago

Works for me, ie. displays "Link broken" if I replace request with "http://request" for example.

fari

Re: Re: How to check if a URL is accessible or not?

3 months ago

Sorry, I think I didn't give a good explanation.

My request is:

request = baseURL+trendName+".json";

e.g. request = http://api.example.com/processing.json

I just want to check if the requested page returns HTTP 404, then I don't want to parse the json.

PhiLho

Re: How to check if a URL is accessible or not?

3 months ago

You can try something like:

import java.net.*;
try
{
URL url= new URL("http://www.processings.org");
URLConnection connection = url.openConnection();
connection.setRequestProperty("User-Agent", "I am a real browser like Mozilla or MSIE" );
String[] results = loadStrings(connection.getInputStream());
println(results);
}
catch (Exception e) // MalformedURL, IO
{
println("Error");
e.printStackTrace();
}

You have to read some data from the server to know if it is reachable or not.

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