Java DNS API not working

Question

I cant seem to figure out how to get this code to work properly. Am I doing something wrong? the program fails on the Record[] records = lookup.run(); line.

import java.util.Iterator;

    import org.xbill.DNS.ARecord;
    import org.xbill.DNS.Lookup;
    import org.xbill.DNS.Record;
    import org.xbill.DNS.TXTRecord;
    import org.xbill.DNS.TextParseException;
    import org.xbill.DNS.Type;
    Lookup lookup;
    try {
        lookup = new Lookup("google.com", Type.ANY);
        Record[] records = lookup.run();

        if (lookup.getResult() == Lookup.SUCCESSFUL) {
            String responseMessage = null;
            String listingType = null;
            for (int i = 0; i < records.length; i++) {
                if (records[i] instanceof TXTRecord) {
                    TXTRecord txt = (TXTRecord) records[i];

                    for (Iterator j = txt.getStrings().iterator(); j.hasNext();) {
                        responseMessage += (String) j.next();
                    }
                } else if (records[i] instanceof ARecord) {
                    listingType = ((ARecord) records[i]).getAddress()
                            .getHostAddress();
                }
            }
        }
    }catch (TextParseException e) {
        e.printStackTrace();
    }

If it fails by printing a stack trace, post the stack trace too. — Edwin Buck
– Edwin Buck, Commented Apr 21, 2011 at 16:03

lobster1234 · Accepted Answer · 2011-04-21 17:47:04Z

1

What do you mean by it does not work? Please paste any exception trace as requested earlier. I was able to run the code just fine, I added output to the records so as to see the result. Here is the code:

import java.util.Iterator;
import org.xbill.DNS.ARecord;
import org.xbill.DNS.Lookup;
import org.xbill.DNS.Record;
import org.xbill.DNS.TXTRecord;
import org.xbill.DNS.TextParseException;
import org.xbill.DNS.Type;

public class DNS {

    public static void main(String[] args) {
        try {
            Lookup lookup = new Lookup("google.com", Type.ANY);
            Record[] records = lookup.run();

            if (lookup.getResult() == Lookup.SUCCESSFUL) {
                String responseMessage = null;
                String listingType = null;
                for (int i = 0; i < records.length; i++) {
                    if (records[i] instanceof TXTRecord) {
                        TXTRecord txt = (TXTRecord) records[i];
                        for (Iterator j = txt.getStrings().iterator(); j
                                .hasNext();) {
                            responseMessage += (String) j.next();
                        }
                        System.out.println("TXRecord " + responseMessage);
                    } else if (records[i] instanceof ARecord) {
                        listingType = ((ARecord) records[i]).getAddress()
                                .getHostAddress();
                        System.out.println("ARecord address : " + listingType);
                    }
                }
            }
        } catch (TextParseException e) {
            e.printStackTrace();
        }
    }
}

And here is the output:

ARecord address : 74.125.224.49
ARecord address : 74.125.224.51
ARecord address : 74.125.224.52
ARecord address : 74.125.224.48
ARecord address : 74.125.224.50
TXRecord nullv=spf1 include:_netblocks.google.com ip4:216.73.93.70/31 ip4:216.73.93.72/31 ~all

answered Apr 21, 2011 at 17:47

lobster1234

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5 Comments

gnomed Over a year ago

if the same code does not work for OP but it works for you, it might be a network configuration issue on the OP's system. I imagine this function requires an internet connection, for a start.

David Over a year ago

I am running this inside of eclipse. The line Record[] records = lookup.run(); returns null. I have an internet connection so I know that is not the problem. Which version of dnsjava are you using could that be it or is it a network configuration issue? No Stack trace is printed it does not get past first if statement. If I comment out the first if statement then it throws a null pointer exception.

lobster1234 Over a year ago

I am using dnsjava-2.0.0.jar. Another option is go to any other network and run the program from there (like home/work/starbucks/library) and see if it works.

David Over a year ago

Figured it out! I was using a corrupt dnsjava-2.0.0.jar. I am now using their smaller dnsjava-2.1.1.jar file and everything works great!

F. Aydemir Over a year ago

I have been having the same problem with the sample code above using the 2.1.1 library. Was there st else you did to solve the issue. Mine is still not working.

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