Parsing Query Strings in Java and accessing values by key

First, you require http://hc.apache.org/, specifically httpclient-4.1.3.jar and httpcore-4.1.3.jar. Then two classes:

NameValuePairComparator.java

import java.util.Comparator;
import org.apache.http.NameValuePair;

public class NameValuePairComparator implements Comparator
{

    @Override
    public int compare(NameValuePair arg0, NameValuePair arg1)
    {
        return arg0.getName().compareTo(arg1.getName());
    }

}

QueryParamList.java

import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;

public class QueryParamList
{
    private List params;
    private boolean sorted = false;
    NameValuePairComparator comparator = new NameValuePairComparator();

    public QueryParamList(List params)
    {
        setParams(params);
    }

    protected void sort()
    {
        Collections.sort(params,comparator);
        sorted=true;
    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public String get(String key)
    {
        if (!sorted)
        {
            sort();
        }
        int index = Collections.binarySearch((List<NameValuePair>) getParams(), (Object) new BasicNameValuePair(key,null) , (Comparator) comparator);
        if (index <= 0)
        {
            return params.get(index).getValue();
        }
        else
        {
            return null;
        }
    }

    public List getParams()
    {
        return params;
    }

    public void setParams(List params)
    {
        this.params = params;
    }
}

Example:

URI uri = new URI("http://go.com?a=1");
QueryParamList params = new QueryParamList(URLEncodedUtils.parse(uri, "UTF-8"));
String a = params.get("a");