I'm working on an app that uses a Web API via HttpGet and it works fine when
part of the onCreate section.
In order to make the code more portable and visible to all the activities I
thought it would be wise to create a helper class.
I copied the code to a new class and now I seem to be getting a
NullPointerException on the DefaultHttpClient.execute(HttpGet); call...
The line in the class code that seems to cause the NPE is:
String responseBody = client.execute(get, responseHandler);
Here is my code in the calling activity:
MyHelper uh = new MyHelper();
JSONObject login = uh.queryHost(this, "user", "pass", "query");
Here is my class code:
public class MyHelper {
private static String hostURL = "http://api.host.com";;
private static String apiURL = "/v3/";
private static String apiKey = "?key=**********";
private ProgressDialog pDialog = null;
private DefaultHttpClient client = null;
public MyHelper() {
// TODO Auto-generated constructor stub
}
public JSONObject queryHost(Context passedContext, String username,String
password, String query){
try {
pDialog = ProgressDialog.show(passedContext, "Please Wait..",
"Connecting to Host",true);
HttpGet get = new HttpGet(hostURL+apiURL+query+apiKey);
get.addHeader("Authorization", "Basic " +
getCredentials(username,password));
ResponseHandler<String> responseHandler = new BasicResponseHandler();
//I've tried both of these below with the same result
String responseBody = client.execute(get, responseHandler);
HttpResponse resp = client.execute(get);
//JSONObject response = new JSONObject(responseBody);
//JSONObject userInfo =
response.getJSONObject("results").getJSONObject("user");
Log.i("Log", "Response: " + "TEST"); //response);
//Log.i("Log", "JSON: " + userInfo);
return new JSONObject(); //response;
} catch (Exception e) {
//pDialog.dismiss();
AlertDialog.Builder dialog = new AlertDialog.Builder(passedContext);
dialog.setTitle("Connection Error");
dialog.setMessage("Unable To Connect To Host, Check Your
Username/Password & Try Again");
dialog.setNeutralButton("Ok", null);
dialog.create().show();
Log.e("Err", "ERROR: ", e);
}
return new JSONObject();
}
public String getCredentials(String username, String password){
return (Base64.encodeBytes((username + ":" + convertToMD5(password)
).getBytes()));
}
public String convertToMD5(String s){
try {
//Create the MD5
MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
digest.update(s.getBytes());
byte messageDigest[] = digest.digest();
//Create Hex
StringBuffer hexString = new StringBuffer();
for (int i=0; i<messageDigest.length; i++)
hexString.append(Integer.toHexString(0xFF & messageDigest[i]));
return hexString.toString();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
return null;
}
}
Here is the NPE:
java.lang.NullPointerException
at com.myapp.MyHelper.queryHost(MyHelper.java:48)
at com.myapp.Startup.onCreate(Startup.java:22)
at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
at android.app.ActivityThread.access$2200(ActivityThread.java:119)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4363)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
at dalvik.system.NativeStart.main(Native Method)
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