StackWrap4J Java wrapper

Question

The StackWrap4J 1.0.1 jar is now available! (See the changelog)

Sample Code / Screen Shot

The following code snippet was used to test the wrapper in the Android emulator:

TextView text = (TextView)findViewById(R.id.output);
StackWrapper stackWrap = new StackOverflow();

String displayText = null;

try {
    Stats stats = stackWrap.getStats();
    displayText = "Stack Overflow Statistics";
    displayText += "\nTotal Questions: " + stats.getTotalQuestions();
    displayText += "\nTotal Unanswered: " + stats.getTotalUnanswered();
    displayText += "\nTotal Answers: " + stats.getTotalAnswers();
    displayText += "\nTotal Comments: " + stats.getTotalComments();
    displayText += "\nTotal Votes: " + stats.getTotalVotes();
    displayText += "\nTotal Users: " + stats.getTotalUsers();
}
catch(Exception e){
    displayText = e.getMessage();
}

text.setText(displayText);

About

StackWrap4J is a Java wrapper for the Stack Exchange API. It is designed to be easy to use, and intuitive to learn while providing the full functionality of the API.

License

StackWrap4J is available under the MIT license.

Download

StackWrap4J

Platform

StackWrap4J was built using Java 1.5 and tested on Sun's JVM. It should run on any implementation of the JVM (1.5 or later). It's also been tested on the Android emulator. It also runs under the Google App Engine.

Code

You can download the code from our SVN repository hosted on SourceForge.

Documentation for the code is also available on the SourceForge site.

Authors

Bill Cruise
Justin Nelson

Contact

Please feel free to leave feedback here in the Answers section or on the StackWrap4J project discussion forum.

Alternatively:

Bill is available at: lizard.bill (at) gmail.com
Justin can be reached at: jjnguy13 (at) gmail.com

Future

Currently we are focusing on adding more tests and fixing bugs. We are also working on adding serialization so that our objects can be easily persisted, and throttling so that users of our library don't have to worry about breaking the terms of use of the API.

Notes

The latest build was tested against version 1.0 of the API on July 28^th.

Answer 1

The following is a quickly thrown together method that will return the accepted answer percentage of the user with the given ID.

Note: This is using some code that will be available in the next release. Notice how it dramatically reduces complexity, and the length of code.

public static double getAcceptedAnswerPercentage(StackWrapper sw, int userId)
        throws JSONException, IOException, ParameterNotSetException {
    int acceptedCount = 0;
    int answerCount = 0;
    List<Answer> answers = new AnswerFromUserList(sw, (AnswerQuery) new AnswerQuery()
            .setIds(userId));
    for (Answer a : answers) {
        answerCount++;
        if (a.isIsAccepted())
            acceptedCount++;
    }
    return acceptedCount / (double) answerCount;
}

Are you tired of manually paging queries? We were too. Introducing the AutoFetchList!!

The class AutoFetchList will automatically pull the next pages as needed. Looks like a list, acts like a list...must be a list. Just throw it a Query and it will take care of the paging for you.

There is a partial implementation of this in the datastructures package of the latest release. It is partially functional. But, the code above will run and work.

Answer 2

Search Examples

Questions

You can search for questions with StackWrap4J by instantiating a StackWrapper then calling the search method. Before calling search, you have to create a SearchQuery, which is a simple parameter object.

StackWrapper so = new StackOverflow();

SearchQuery query = new SearchQuery();
query.setTags("swing");
query.setNotTagged("java");
query.setPageSize(10);

List<Question> questions = so.search(query);
System.out.println("Questions: " + questions.size());

for(Question q : questions) {
    System.out.println("Id " + q.getPostId() + ":\t" + q.getTitle());
    System.out.println("Tags: " + q.getTags());
}

If you don't set the tags, nottagged, or intitle parameter in the SearchQuery, the search method will throw an exception.

If you need to modify your search, you can reuse the same query. If I decide I want to add the [scala] tag to the search I did above, I could just add the tag and call search again.

query.addTag("scala");
questions = so.search(query);
...

Users

You can do a search for users with similar names using the listUsers method and a UserQuery object. You just have to set the filter in the query.

UserQuery uquery = new UserQuery();
uquery.setFilter("Bill");
uquery.setPageSize(10);
List<User> bills = so.listUsers(uquery);

for(User u : bills) {
    System.out.println("Username: " + u.getDisplayName());
}

Answer 3

Proxy Example

Sometimes you need to use a Proxy to access the internet. At my company we need to. StackWrap4J provides the ability to specify a Proxy server to rout connections through.

Below is a short code sample that configures the proxy, and then pulls every answer that I (2598) have given.

Proxy prox = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(
            "proxy.my.company.com", 80));
HttpClient.proxyServer = prox;
StackWrapper sw = new StackOverflow();
AnswerQuery query = new AnswerQuery();
query.setPageSize(PageQuery.MAX_PAGE_SIZE).setIds(2598);
List<Answer> allAnswers = new AnswerFromUserList(sw, query);

It is as simple as setting the public proxyServer property of the HttpClient class. That proxy will be used continually unless you set proxyServer to null.

Answer 4

Timeout Example

If you find that a response is taking too long for your app, you can set a timeout on the request.

If a timeout occurs, a java.net.SocketTimeoutException is thrown. The default timeout is 0 which means infinite, so you don't have to worry about the exception if you never set a timeout.

StackWrapper sw = new StackOverflow();
// Set the timeout globally (1ms is way too short)
// But you will get to see the exception generated
HttpClient.setTimeout(1); // You shouldn't use 1, it will always timeout
sw.getUserById(2598);

So, instead of waiting for the response forever, you can time it out, and ask the user to try again later.

(This is very similar to how you would set the proxy server like in the proxy example)

Answer 5

Version Updates:

Version 1.0.1 [download]

• Added serialization to StackWrapper, all entities, and all queries
• Url encoded user entered String parameters (i.e. " " => "%20")
• Set followRedirect on each connection instance instead of JVM-wide. (This was causing problems with Google App Engine)

Answer 6

Thanks for this, I was able to get an Android proof-of-concept working very quickly.

I wanted to build the latest version from SVN because it has some changes that aren't in the most recent binary but there doesn't appear to be a build script in the repository. The structure seems straightforward, so I could write my own build.xml, but maybe you have something already that you use?

One minor suggestion I have is that it would be more convenient if the API docs were on the web somewhere rather, particularly for people who just want to browse to get an idea of the structure and capabilities of the library.

Answer 7

Are there any plans to support the use of your library in GWT? I'm getting some security-related errors trying to get it to work. See http://pastebin.com/SJTAHP0B

Answer 8

Can I authenticate my android app via your library? If not, please add that if you can.