We Keep Coding

How to populate a RecyclerView with data from a Service on Button click

I have this setup in my fragment. The user makes selections from the spinners and when they click the go button a service is initiated that is meant to get data and populate a recycler view with the data.The recycler view is located right below the spinners.The code is below.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<Spinner
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/weekSpinner"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_margin="5dp">
</Spinner>
<Spinner
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/sessionSpinner"
android:layout_toRightOf="#+id/weekSpinner"
android:layout_toEndOf="#+id/weekSpinner"
android:layout_margin="5dp">
</Spinner>
<Spinner
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/termSpinner"
android:layout_toRightOf="#+id/sessionSpinner"
android:layout_toEndOf="#+id/sessionSpinner"
android:layout_margin="5dp">
</Spinner>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Go"
android:id="#+id/resultsSearch"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_margin="10dp"
android:layout_below="#+id/sessionSpinner"
android:textColor="#android:color/white"
android:background="#color/toolBar"/>
</RelativeLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/caRecycler">
</android.support.v7.widget.RecyclerView>
</LinearLayout>
</LinearLayout>
I am getting this error.
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
I understand that it has to do with the context being used but i have no idea how to solve it as this is the first time i'm using this sort of setup. Below is my fragment code.
public class caFragment extends Fragment
{
ArrayList<String> weeks,terms,sessions;
String selectedWeek,selectedTerm,selectedSession;
String activeChild;
Button go;
private static final String selectedChildTracker = "selectedChild";
SharedPreferences sharedpreferences;
static RecyclerView caDisplay = null;
static caCardAdapter cardAdapter = null;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.results_ca,null);
sharedpreferences = this.getActivity().getSharedPreferences(selectedChildTracker, Context.MODE_PRIVATE);
activeChild = sharedpreferences.getString("selectedChild",null);
final Spinner week,term,session;
setup();
week = (Spinner) view.findViewById(R.id.weekSpinner);
ArrayAdapter<String> weekAdapter = new ArrayAdapter<>(getContext(),android.R.layout.simple_spinner_item,weeks);
weekAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
week.setAdapter(weekAdapter);
term = (Spinner) view.findViewById(R.id.termSpinner);
ArrayAdapter<String> termAdapter = new ArrayAdapter<>(getContext(),android.R.layout.simple_spinner_item,terms);
termAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
term.setAdapter(termAdapter);
session = (Spinner) view.findViewById(R.id.sessionSpinner);
ArrayAdapter<String> sessionAdapter = new ArrayAdapter<>(getContext(),android.R.layout.simple_spinner_item,sessions);
sessionAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
session.setAdapter(sessionAdapter);
caDisplay = (RecyclerView) view.findViewById(R.id.caRecycler);
go = (Button) view.findViewById(R.id.resultsSearch);
go.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
selectedWeek = week.getSelectedItem().toString();
selectedTerm = term.getSelectedItem().toString();
selectedSession = session.getSelectedItem().toString();
Bundle extra = new Bundle();
extra.putString("selectedWeek",selectedWeek);
extra.putString("selectedTerm",selectedTerm);
extra.putString("selectedSession",selectedSession);
extra.putString("selectedChild",activeChild);
try
{
getActivity().startService(new Intent(getContext(), results.class).putExtras(extra));
}
catch (Exception ex)
{
System.out.print(ex);
}
}
});
return view;
}
public void setup()
{
weeks = new ArrayList<>();
terms = new ArrayList<>();
sessions = new ArrayList<>();
try
{
weeks.add("4");
weeks.add("8");
}
catch (Exception ex)
{
Log.e("Error adding weeks",ex.toString());
}
try
{
terms.add("First Term");
terms.add("Second Term");
terms.add("Third Term");
}
catch (Exception ex)
{
Log.e("Error adding terms",ex.toString());
}
try
{
sessions.add("2015/2016");
}
catch (Exception ex)
{
Log.e("Error adding sessions",ex.toString());
}
}
public void showResults()
{
cardAdapter = new caCardAdapter(getActivity(),cardResults.getResultSet());
caDisplay.setAdapter(cardAdapter);
caDisplay.setLayoutManager(new LinearLayoutManager(getActivity()));
}
}
and below is my service code
public class results extends Service
{
int mStartMode;
String tag_results_req = "tag_results_req";
static ArrayList<cardResults> cardResult;
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public int onStartCommand(Intent intent, int flags, int startId)
{
Bundle params = intent.getExtras();
Log.d("bundle param",params.toString());
String week = params.getString("selectedWeek");
String term = params.getString("selectedTerm");
String session = params.getString("selectedSession");
String child = params.getString("selectedChild");
makeRequest(week,term,session,child);
return mStartMode;
}
#Override
public void onDestroy()
{
super.onDestroy();
}
public void makeRequest(String week,String term,String session,String child)
{
String dataSet = week.trim()+","+term+","+session.trim()+","+child.trim();
byte[] data = new byte[0];
try
{
data = dataSet.getBytes("UTF-8");
}
catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
String query = Base64.encodeToString(data, Base64.DEFAULT);
Log.d("Query param",query);
//the url we are posting the request to
String url = " http://mobile.map.education/api/result/ca/"+query;
// prepare the Request
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>()
{
#Override
public void onResponse(JSONObject response)
{
// display response
Log.d("results",response.toString());
cardResults(response);
}
},
new Response.ErrorListener()
{
#Override
public void onErrorResponse(VolleyError error)
{
Log.e("Error.Response", error.toString());
Toast.makeText(getApplicationContext(),"Sorry there was an error getting results data",Toast.LENGTH_LONG).show();
}
}
);
queuer.getInstance().addToRequestQueue(request, tag_results_req);
}
public void cardResults(JSONObject result)
{
cardResult = new ArrayList<>();
JSONArray res = null;
try
{
res = (JSONArray) result.get("result_details");
Log.d("results",res.toString());
}
catch (Exception ex)
{
Log.e("error getting results",ex.toString());
}
for (int i = 0; i < res.length(); i++)
{
try
{
JSONObject subject = res.getJSONObject(i);
cardResults cardModel = new cardResults();
cardModel.setAverage("50");
cardModel.setScore(subject.getString("total"));
cardModel.setSubject(subject.getString("subject"));
cardModel.setAssignment(subject.getString("ASSIGNMENT"));
cardModel.setTest(subject.getString("CLASS TEST"));
cardModel.setWork(subject.getString("CLASS WORK"));
cardModel.setTeacher(subject.getString("teacher"));
cardResult.add(cardModel);
}
catch (Exception ex)
{
Log.e("card list",ex.toString());
}
}
try {
cardResults.setResultSet(cardResult);
caFragment m = new caFragment();
m.showResults();
}
catch (Exception ex)
{
Log.e("show result",ex.toString());
}
}
}

Looks like problem with your adapter which you are setting outside the onCreate of Fragment
cardAdapter = new caCardAdapter(getActivity());
caDisplay.setAdapter(cardAdapter);
caDisplay.setLayoutManager(new LinearLayoutManager(getActivity()));
move above lines inside the onCreate and just create one data Setter method in your Adapter class and then call this method to set data.
public void showResults()
{
//create setter method inside your adapter and notify
cardAdapter.setData(cardResults.getResultSet());
cardAdapter.notifyDataSetChanged();
}
before set Data just check that your data is not null!

Android Calling API and parsing JSON

Trying to make an API call to the url below and parse the returning JSON, when the "refresh" button is called.
I can link to a button and get text (Hello world) to the screen, but can't seem to link the button click to the API request. Error message says I cannot reference non-static method "execute" from a static context
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void retrieveInformation(View view){
RetrieveFeedTask.execute();
TextView textview = (TextView) findViewById(R.id.responseView);
textview.setText("Hello world");
}
class RetrieveFeedTask extends AsyncTask<Void, Void, String> {
String jsonString = "";
private Exception exception;
protected void onPreExecute() {
}
protected String doInBackground(Void... urls) {
// Do some validation here
try {
URL url = new URL("www.liftin.co.uk/api/v1/journeys");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder stringBuilder = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line).append("\n");
}
bufferedReader.close();
return stringBuilder.toString();
} finally {
urlConnection.disconnect();
}
} catch (Exception e) {
Log.e("ERROR", e.getMessage(), e);
return null;
}
}
protected void onPostExecute(String response) {
if (response == null) {
response = "THERE WAS AN ERROR";
}
Log.i("INFO", response);
jsonString = response;
try {
getInformationFromJson(jsonString);
} catch (JSONException e) {
e.printStackTrace();
}
}
private String getInformationFromJson(String jsonString)
throws JSONException {
final String DRIVER = "driver";
final String START = "start";
final String DESTINATION = "destination";
final String TIME = "pick_up_time";
final String PASSENGERS = "passengers";
final String SEATS = "seats_available";
JSONObject journeyJson = new JSONObject(jsonString);
String time = journeyJson.getString(TIME);
String seats = journeyJson.getString(SEATS);
String results = seats + "-----" + time;
return results;
}
}
}
Main_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context="com.example.android.liftin.MainActivity">
<Button
android:id="#+id/queryButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="end"
style="#style/Base.Widget.AppCompat.Button.Borderless"
android:text="Refresh"
android:onClick="retrieveInformation"/>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/responseView"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</ScrollView>
</RelativeLayout>
</LinearLayout>

You should create asynchronous call for your AsyncTask like this :
public void retrieveInformation(View view){
new RetrieveFeedTask().execute(); //asynchronous call
TextView textview = (TextView) findViewById(R.id.responseView);
textview.setText("Hello world");
}
UPDATE
If you want to set data to textview after parsing data. You have to make little bit changes in your activity as follows.
You should initialize your textview in onCreate() and make it global variable for your activity, so that you can access it in full activity.
then in your onPostExecute() do this :
textview.setText(getInformationFromJson(response));
Hope it will Help :)

You must create a object of AsyncTask (RetrieveFeedTask) before calling it. For example
public void retrieveInformation(View view){
TextView textview = (TextView) findViewById(R.id.responseView);
textview.setText("Hello world");
new RetrieveFeedTask().execute();
}

You still need to pass something for Void.
public void retrieveInformation(View view){
new RetrieveFeedTask().execute(null);
TextView textview = (TextView) findViewById(R.id.responseView);
textview.setText("Hello world");
}

Displaying picture, name and description in a listView android

Im trying to display some information from my Items[] in a listview, the information is retrived from database. what I want to display is a picture, name and description. note that the picture is retrived in base64 string so I have to convert it before sending data.
I tried this:
for(int x=0;x<items.length;x++) {
byte[] decodedString = Base64.decode(items[x].Picture, Base64.DEFAULT);
Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
ListAdapter adapter = new SimpleAdapter(Itemlist.this, (List<? extends Map<String, ?>>) listView, R.layout.layout, new String[]{items[x].Name, items[x].Description}, new int[]{R.id.move_title, R.id.move_rating});
setListAdapter(adapter);
}
but I got this error:
java.lang.ClassCastException: android.widget.ListView cannot be cast to java.util.List
this is the activity layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin" tools:context=".MainActivity"
android:background="#ffffff"
>
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</RelativeLayout>
and the list layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="#ffffff"
>
<ImageView
android:id="#+id/move_poster"
android:layout_width="100dp"
android:layout_height="75dp"
android:layout_alignParentLeft="true"
/>
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#FFFFFF"
android:layout_alignRight="#+id/move_poster"
android:layout_alignEnd="#+id/move_poster"
android:layout_below="#+id/move_poster">
</View>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="#+id/move_title"
android:layout_alignParentTop="true"
android:layout_toRightOf="#+id/move_poster"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text"
android:id="#+id/move_rating"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_below="#+id/move_title"
android:layout_toRightOf="#+id/move_poster"
android:layout_toEndOf="#+id/move_poster"
android:layout_alignBottom="#+id/move_poster" />
</RelativeLayout>
and this is the whole activity class:
public class Itemlist extends ListActivity {
private Handler mHandler= new Handler();
Item[] items;
ListView listView;
MoveAdapter adapter;
TextView tv;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_itemlist);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
listView=getListView();
tv=(TextView)findViewById(R.id.textView);
String[] params= new String[]{"192.168.1.11:90"};
new MyAsyncTask().execute(params);
}
class MyAsyncTask extends AsyncTask<String, Void, String>
{
public String SOAP_ACTION="http://tempuri.org/GetAllItems";
public String OPERATION_NAME ="GetAllItems";
public String WSDL_TARGET_NAMESPACE ="http://tempuri.org/";
public String SOAP_ADDRESS;
private SoapObject request;
private HttpTransportSE httpTransport;
private SoapSerializationEnvelope envelop;
Object response= null;
#Override
protected String doInBackground(String... params) {
SOAP_ADDRESS = "http://" + params[0] + "/myWebService2.asmx";
request = new SoapObject(WSDL_TARGET_NAMESPACE, OPERATION_NAME);
envelop = new SoapSerializationEnvelope(SoapEnvelope.VER11);
envelop.dotNet = true;
envelop.setOutputSoapObject(request);
httpTransport = new HttpTransportSE(SOAP_ADDRESS);
try {
httpTransport.call(SOAP_ACTION, envelop);
SoapObject response = (SoapObject) envelop.getResponse();
items = new Item[response.getPropertyCount()];
for (int i = 0; i < items.length; i++) {
SoapObject pii = (SoapObject) response.getProperty(i);
Item item = new Item();
item.Name = pii.getProperty(0).toString();
item.Description = pii.getProperty(1).toString();
item.Picture = pii.getProperty(2).toString();
item.ID = Integer.parseInt(pii.getProperty(3).toString());
items[i] = item;
}
} catch (XmlPullParserException e) {
e.printStackTrace();
} catch (SoapFault soapFault) {
soapFault.printStackTrace();
} catch (HttpResponseException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return "Done"; }
#Override
protected void onPostExecute(final String result){
super.onPostExecute(result);
mHandler.post(new Runnable() {
#Override
public void run() {
tv.setText(result);
for(int x=0;x<items.length;x++) {
byte[] decodedString = Base64.decode(items[x].Picture, Base64.DEFAULT);
Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
ListAdapter adapter = new SimpleAdapter(Itemlist.this, (List<? extends Map<String, ?>>) listView, R.layout.layout, new String[]{items[x].Name, items[x].Description}, new int[]{R.id.move_title, R.id.move_rating});
setListAdapter(adapter);
}
}
});
}
}
}
also I don't know how to send the bitmap format of the picture to the adapter, because it only takes Strings.
can someone please help me displaying the listview of images, name and description?

Actually i think i have some time to do it now,
here we go.
but first you need to read and learn Custom adapter for listView
you can google it and understand how it works,
then come back to this answer.
here you can findsome good sample for a custom adapter
you really need to read and understand it.
now, some code changes for your's
1- modify your Item class to have a Bitmap Member
public Bitmap bitmap;
adding setter and getter is better. but you can make it public and access it directly
2- [Optional] in Itemlist activity, declare Arraylist instead of array
you will learn more about this when you search for custom adapter, as you can pass data as Array or as List
private ArrayList<Item> items = new ArrayList();
3- modify the for loop as following: (assuming you did not changed to arrayList and still use array[])
for(int x=0;x<items.length;x++) {
byte[] decodedString = Base64.decode(items[x].Picture, Base64.DEFAULT);
Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
items[x].bitmap = decodedByte;
}//for loop end
4- declare adapter (instance of your Custom Adapter), and assign it to the listView
MyCustomAdapter adapter = new MyCustomAdapter(ItemsList.this, R.layout.list_row, items);
setListAdapter(adapter);
now in your adapter's getView() method, you can use the memebrs (name, desc, bitmap) to populate the custom layout of each row
that's it.
P.S: this code is not all compiled, and may contain some typos,
it's just to guide you through the process.

Can you please help me with this code?

The problem: When I Type a ID and press the button, it will not load the ID's webpage...
"a url" is the website page i'm trying to create, (Hidden for number of reasons)
It should be working, it loads the first site, but when I try to call for the IDs, the WebView does not change... Can someone please help me? -Thanks, JG1
My code:
#Override
protected void onCreate(Bundle savedInstanceState) {
requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
wv.setWebViewClient(new OurViewClient());
wv.getSettings().setJavaScriptEnabled(true);
try {
String url = "a url";
wv.loadUrl(url);
} catch (Exception e) {
e.printStackTrace();
}
String lid = "0";
//Clicking button changes to the color
}
final EditText idbox = (EditText) findViewById(R.id.editText1);
final Button idbutton = (Button) findViewById(R.id.idbtn);
final WebView wv = (WebView) findViewById(R.id.webView1);
public void onClick(View v) {
idbutton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
String lid = idbox.getText().toString();
if (lid == "1") {
wv.setWebViewClient(new OurViewClient());
try {
String urla = "a url";
wv.loadUrl(urla);
} catch (Exception e) {
e.printStackTrace();
}
}
if (lid == "2") {
wv.setWebViewClient(new OurViewClient());
try {
String urlb = "a url";
wv.loadUrl(urlb);
} catch (Exception e) {
e.printStackTrace();
}
}
if (lid == "3") {
wv.setWebViewClient(new OurViewClient());
try {
String urlc = "a url";
wv.loadUrl(urlc);
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
}

I guess, You had been called the same URL value like ("a url"). If yes, try to load different URLs in the web view.
If not, do the following changes in your code,
Put break points to debug your code where you get EditText value.
String lid = idbox.getText().toString(); //check lid is null or not
Change the if condition like this,
if(lid.equalsIgnoreCase("1"))
{
//task for rendering web page
}
Check your custom view client class.

Never mind, You written onClick() method definition is wrongly!
I confused because,
Have you been adding the onclick(android:onClick="onClick") function for button in xml.
In spite of I did some bit changes in your code,
activity_main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="2" >
<EditText
android:id="#+id/urlValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="2dp"
android:layout_weight="1.5" />
<Button
android:id="#+id/urlBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="2dp"
android:layout_weight="0.5"
android:text="load"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<WebView
android:id="#+id/webView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
MainActivity.java:
public class MainActivity extends Activity {
private EditText getUrlValue;
private Button loadUrl;
private WebView webView;
String loadId = "";
String URL_ONE = "a_url";
String URL_TWO = "b_url";
String URL_THREE = "c_url";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getUrlValue = (EditText)findViewById(R.id.urlValue);
loadUrl = (Button)findViewById(R.id.urlBtn);
webView = (WebView)findViewById(R.id.webView);
//initial view for webView
getUrlValue.setText("1"); //here web page will load first url= "a url"
webView.setWebViewClient(new OurViewClient());
//onClick Event for load url button
loadUrl.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
loadId = getUrlValue.getText().toString();
if(loadId.equalsIgnoreCase("1")){
try{
webView.loadUrl(URL_ONE);
}catch (Exception e){
e.printStackTrace();
}
}
else if(loadId.equalsIgnoreCase("2")){
try{
webView.loadUrl(URL_TWO);
}catch (Exception e){
e.printStackTrace();
}
}
else{
try{
webView.loadUrl(URL_THREE);
}catch (Exception e){
e.printStackTrace();
}
}
}
});
}
}
remember to add internet permission in the manifest xml file.

Method not found at run time

I use the org.apache.commons.io.FileUtils.readFileToByteArray method in myAndroid application. I imported the jar file and I see this method is in my project. (I use Eclipse.) Actually, compilation is ok. Here's the message from LogCat:
01-26 18:43:08.177: I/dalvikvm(897): Could not find method org.apache.commons.io.FileUtils.readFileToByteArray, referenced from method com.example.anagrams.MainActivity.readFile
So this is not an error, but then I get a NullPointerException due, apparently, to the statement:
private Button button_read_file = (Button) findViewById(R.id.button_readfile);
I have no idea how to correct the NullPointerException. Also I am puzzled by the message about the method not found. The application is supposed to read a text file containing English words and then for each word to find all the anagrams that exist. For the moment I just use System.out.println to write the anagrams.
Any help is welcome. Following is my whole MainActivity (the only one so far):
public class MainActivity extends Activity {
private String[] words;
private Button button_read_file = (Button) findViewById(R.id.button_readfile);
private EditText input_file_name = (EditText) findViewById(R.id.editText1) ;
private Button button_write_file = (Button) findViewById(R.id.button_writefile);
private EditText output_file_name = (EditText) findViewById(R.id.editText2) ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button_read_file.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String inputFileName = input_file_name.getText().toString();
try {
words = readFile(inputFileName, Charset.defaultCharset());
} catch (FileNotFoundException e) {
e.getStackTrace();
} catch (IOException ioe) {
ioe.getStackTrace();
}
}});
button_write_file.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
for (int i = 0; i < words.length; ++i) {
String s = words[i];
System.out.println(" words[" + i + "] = " + s);
HashSet<String> a = new HashSet<String>();
permutations(s,a);
Iterator<String> iterator = a.iterator();
while(iterator.hasNext()) {
System.out.println(iterator.next());
}
}
}});
}
public String[] readFile(String path, Charset encoding) throws IOException {
File file = new File(path);
byte[] encoded = FileUtils.readFileToByteArray(file);
String s = encoding.decode(ByteBuffer.wrap(encoded)).toString();
s = s.replace(" ","");
return s.split("[,.\\n\\s]");
}
public ArrayList<String> getDictionary(String filename) throws IOException, FileNotFoundException {
ArrayList<String> dictionary = new ArrayList<String>();
FileReader fileReader = new FileReader(filename);
BufferedReader bufferedReader = new BufferedReader(fileReader);
String line = null;
while ((line = bufferedReader.readLine()) != null) {
dictionary.add(line);
}
bufferedReader.close();
return dictionary;
}
public boolean isInDictionary(String s) {
String dictionaryname = "enable1.txt";
ArrayList<String> dictionary = new ArrayList<String>();
try {
dictionary = getDictionary(dictionaryname);
} catch (FileNotFoundException e) {
e.getStackTrace();
} catch (IOException e) {
e.getStackTrace();
}
if (dictionary.contains(s))
return true;
else
return false;
}
public void permutations(String word, HashSet<String> anagrams) {
generatePermutations("",word,anagrams);
}
public void generatePermutations(String prefix, String word, HashSet<String> anagrams) {
int n = word.length();
if (n == 0) {
if (prefix != word && isInDictionary(prefix))
anagrams.add(prefix);
}
else {
for (int i = 0; i < n; ++i) {
generatePermutations(prefix + word.charAt(i),word.substring(0,i) + word.substring(i+1),anagrams);
}
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
And here's the layout file:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="#+id/button_readfile"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="17dp"
android:text="#string/read_file" />
<Button
android:id="#+id/button_writefile"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/button_readfile"
android:layout_below="#+id/button_readfile"
android:layout_marginTop="24dp"
android:text="#string/write_file" />
<EditText
android:id="#+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/button_readfile"
android:layout_toRightOf="#+id/button_writefile"
android:ems="10" >
<requestFocus />
</EditText>
<EditText
android:id="#+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="#+id/button_writefile"
android:layout_alignBottom="#+id/button_writefile"
android:layout_alignLeft="#+id/editText1"
android:ems="10" >
</EditText>

You are initializing these before the layout is even set:
private Button button_read_file = (Button) findViewById(R.id.button_readfile);
private EditText input_file_name = (EditText) findViewById(R.id.editText1) ;
private Button button_write_file = (Button) findViewById(R.id.button_writefile);
private EditText output_file_name = (EditText) findViewById(R.id.editText2) ;
Change them to:
private Button button_read_file;
private EditText input_file_name;
private Button button_write_file;
private EditText output_file_name;
Then declare them after setContentView(...) in your onCreate like:
button_read_file = (Button) findViewById(R.id.button_readfile);
input_file_name = (EditText) findViewById(R.id.editText1) ;
button_write_file = (Button) findViewById(R.id.button_writefile);
output_file_name = (EditText) findViewById(R.id.editText2) ;
If you see NoClassDefFoundError, try this in Eclipse:
Go to Project Properties → Java Build Path → Order and Export tab.
Check the Android Private Libraries option.