trying to get access authorization token thru java code but salesforce either return "internal server error - 500". 
Same URL and parameters work fine from postman 

public class RestWork
{
    private static final String CONSUMER_KEY = "3MVG9PbXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXzCH";
    private static final String CONSUMER_SECRET = "11111111111111111111";
       
    public static void main(String[] args) throws IOException
    {
              HttpClient client =  new DefaultHttpClient();;
              String loginURL = "https://cs51.salesforce.com/services/oauth2/token";    
        
        HttpPost httpPost = new HttpPost(loginURL);
       
     params.add(new BasicNameValuePair("client_id",  URLEncoder.encode(CONSUMER_KEY,"UTF-8")));
     params.add(new BasicNameValuePair("client_secret",  URLEncoder.encode(CONSUMER_SECRET,"UTF-8")));
     params.add(new BasicNameValuePair("grant_type", URLEncoder.encode("password","UTF-8")));
     params.add(new BasicNameValuePair("username", "nCCCCC@XXXXXX.com"));
     params.add(new BasicNameValuePair("password",  "PPPPPPPPPPP!23dddddddddddddddddddddddddd"));
  
    httpPost.setEntity(new UrlEncodedFormEntity(params));
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
        HttpResponse response = client.execute(httpPost);
       String body = EntityUtils.toString(response.getEntity());
         System.out.println(body);
      }
}