I am making an food ordering app, just recently download the source code from https://github.com/G-Maniteja/Android-PHP-MySQL-BootStrap-FoodOrder. I have fix few errors that i have but now i am stuck at this part. Can someone please tell me how to fix it?
The error
java.lang.NullPointerException: Attempt to invoke virtual method 'int org.json.JSONArray.length()' on a null object reference
at com.example.manitejagande.foodorder.MenuItemDataModel.fromJson(MenuItemDataModel.java:29)
The full error
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.manitejagande.foodorder, PID: 15899
java.lang.NullPointerException: Attempt to invoke virtual method 'int org.json.JSONArray.length()' on a null object reference
at com.example.manitejagande.foodorder.MenuItemDataModel.fromJson(MenuItemDataModel.java:29)
at com.example.manitejagande.foodorder.CartActivity$AsyncGet1.onPostExecute(CartActivity.java:387)
at com.example.manitejagande.foodorder.CartActivity$AsyncGet1.onPostExecute(CartActivity.java:304)
at android.os.AsyncTask.finish(AsyncTask.java:667)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:684)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
MenuItemDataModel.Java
package com.example.manitejagande.foodorder;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
public class MenuItemDataModel {
public String itemname;
public String itemprice;
`
public MenuItemDataModel(JSONObject object) {
try
{
this.itemname = object.getString("itemname");
this.itemprice = object.getString("itemprice");
}
catch (JSONException e)
{
e.printStackTrace();
}
}
//itemname and itemprice values retrieval from JSON Array..
public static ArrayList<MenuItemDataModel> fromJson(JSONArray jsonObjects)
{
ArrayList<MenuItemDataModel> menuitems = new ArrayList<MenuItemDataModel>();
for (int i = 0; i < jsonObjects.length(); i++) //ERROR this line
{
try
{
menuitems.add(new MenuItemDataModel(jsonObjects.getJSONObject(i)));
}
catch (JSONException e)
{
e.printStackTrace();
}
}
return menuitems;
}
}
There is also an Adapter MenuItemAdapter.java
package com.example.manitejagande.foodorder;
import android.content.Context;
import android.content.SharedPreferences;
import android.net.Uri;
import android.preference.PreferenceManager;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.view.LayoutInflater;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class MenuItemAdapter extends RecyclerView.Adapter<MenuItemAdapter.MenuItemViewHolder>
{
Context context;
ArrayList<MenuItemDataModel> data;
public MenuItemAdapter(Context context,ArrayList<MenuItemDataModel> data) {
this.data = data;
this.context=context;
}
@NonNull
@Override
public MenuItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.menu_list_item, parent, false);
MenuItemViewHolder myViewHolder = new MenuItemViewHolder(view);
return myViewHolder;
}
public String getDefaults(String key, Context context) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
return preferences.getString(key, null);
}
@Override
public void onBindViewHolder(@NonNull MenuItemViewHolder holder, int position) {
TextView itemname=holder.itemname;
TextView itemprice=holder.itemprice;
Button additem=holder.additem;
final Button qsub=holder.qsub;
final TextView qty=holder.qty;
Button qadd=holder.qadd;
final String name=data.get(position).itemname.toString();
final String price=data.get(position).itemprice.toString();
itemname.setText(name);
itemprice.setText(price);
qty.setText("0");
qsub.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(qty.getText().toString().equals("0"))
{
//Log.i("qwer123456","12345"+qty.getText().toString());
Toast.makeText(qsub.getContext(), "Cannot decrease the Quantity..",Toast.LENGTH_SHORT).show();
}
else
{
int qty1=Integer.parseInt(qty.getText().toString());
qty1--;
qty.setText(Integer.toString(qty1));
}
}
});
qadd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int qty1=Integer.parseInt(qty.getText().toString());
qty1++;
qty.setText(Integer.toString(qty1));
}
});
additem.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//String url="https://inamtginamtg.000webhostapp.com/cart.php";
if(qty.getText().toString().equals("0"))
{
Toast.makeText(context,"Please add Quantity of the Item..",Toast.LENGTH_SHORT).show();
}
else {
String url = LoginActivity.weburl + "cart.php";
String email = getDefaults("userid", context);
Uri.Builder builder = new Uri.Builder()
.appendQueryParameter("email", email)
.appendQueryParameter("itemname", name)
.appendQueryParameter("itemprice", price)
.appendQueryParameter("qty",qty.getText().toString());
String query = builder.build().getEncodedQuery();
Log.i("url", query);
Toast.makeText(context, "Item Added Successfully..!", Toast.LENGTH_SHORT).show();
Async_Task a = new Async_Task(context, url, query, true);
a.execute();
Toast.makeText(context, "Item added to Cart", Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public int getItemCount() {
return data.size();
}
public static class MenuItemViewHolder extends RecyclerView.ViewHolder
{
TextView itemname;
TextView itemprice;
Button additem;
Button qsub;
Button qadd;
TextView qty;
public MenuItemViewHolder(View itemView) {
super(itemView);
this.itemname=(TextView)itemView.findViewById(R.id.itemname);
this.itemprice=(TextView)itemView.findViewById(R.id.itemprice);
this.additem=(Button)itemView.findViewById(R.id.additem);
this.qsub=(Button)itemView.findViewById(R.id.qsub);
this.qty=(TextView)itemView.findViewById(R.id.qty);
this.qadd=(Button)itemView.findViewById(R.id.qadd);
}
}
}
CartActivity.Java
package com.example.manitejagande.foodorder;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import static com.example.manitejagande.foodorder.CartActivity.CONNECTION_TIMEOUT;
import static com.example.manitejagande.foodorder.CartActivity.READ_TIMEOUT;
public class CartActivity extends AppCompatActivity {
public static final int CONNECTION_TIMEOUT=10000;
public static final int READ_TIMEOUT=15000;
Context context=this;
String response;
ListView listView;
String email;
String oids;
int total=0;
private static RecyclerView.Adapter adapter;
private static RecyclerView.Adapter adapter1;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.LayoutManager layoutManager1;
private static RecyclerView recyclerView;
private static RecyclerView recyclerView1;
Button placeorder;
static TextView total_text;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cart);
email=getDefaults("userid",this);
total_text=(TextView)findViewById(R.id.totalprice);
recyclerView = (RecyclerView) findViewById(R.id.recyclercart);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
placeorder=(Button)findViewById(R.id.placeorder);
recyclerView1 = (RecyclerView) findViewById(R.id.cart_suggestion_recycler);
recyclerView1.setHasFixedSize(true);
layoutManager1 = new LinearLayoutManager(this);
recyclerView1.setLayoutManager(layoutManager1);
recyclerView1.setItemAnimator(new DefaultItemAnimator());
// String url="http://192.168.0.2/foodorder/showcart.php?email="+email;
FloatingActionButton ca_fab=(FloatingActionButton)findViewById(R.id.ca_fab);
ca_fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i=new Intent(CartActivity.this,MainActivity.class);
startActivity(i);
}
});
AsyncGet a=new AsyncGet();
a.execute();
}
public static String getDefaults(String key, Context context) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
return preferences.getString(key, null);
}
public class AsyncGet extends AsyncTask<String, String, String>
{
ProgressDialog pdLoading = new ProgressDialog(CartActivity.this);
HttpURLConnection conn;
URL url = null;
String results="";
@Override
protected void onPreExecute() {
super.onPreExecute();
//this method will be running on UI thread
pdLoading.setMessage("\tLoading...");
pdLoading.setCancelable(false);
pdLoading.show();
}
@Override
protected String doInBackground(String... params) {
try {
// Enter URL address where your php file resides
// url = new URL("https://inamtginamtg.000webhostapp.com/showcart.php?email="+email);
url = new URL(LoginActivity.weburl+"showcart.php?email="+email);
Log.i("url1",url.toString());
} catch (MalformedURLException e) {
e.printStackTrace();
return "exception";
}
try {
// Setup HttpURLConnection class to send and receive data from php and mysql
conn = (HttpURLConnection)url.openConnection();
conn.setReadTimeout(READ_TIMEOUT);
conn.setConnectTimeout(CONNECTION_TIMEOUT);
conn.setRequestMethod("GET");
// setDoInput and setDoOutput method depict handling of both send and receive
conn.setDoInput(true);
conn.setDoOutput(true);
// Append parameters to URL
//Uri.Builder builder = new Uri.Builder();
//String query = builder.build().getEncodedQuery();
Log.i("url2",url.toString());
// Open connection for sending data
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
// writer.write(query);
writer.write(url.toString());
writer.flush();
writer.close();
os.close();
conn.connect();
} catch (IOException e1) {
e1.printStackTrace();
return "exception";
}
try {
int response_code = conn.getResponseCode();
// Check if successful connection made
//if (response_code == HttpURLConnection.HTTP_OK) {
// Read data sent from server
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
StringBuilder result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
results=result.toString();
response=results;
Log.i("result",results);
// Pass data to onPostExecute method
return(result.toString());
// }else{
//
// return("unsuccessful");
// }
} catch (IOException e) {
e.printStackTrace();
return "exception";
} finally {
conn.disconnect();
}
}
@Override
protected void onPostExecute(String result) {
//this method will be running on UI thread
pdLoading.dismiss();
JSONArray jsonArray = null;
try {
jsonArray = new JSONArray(response);
} catch (JSONException e) {
e.printStackTrace();
}
ArrayList<CartItemDataModel> itemslist = CartItemDataModel.fromJson(jsonArray);
//CartAdapter adapter = new CartAdapter(CartActivity.this, itemslist);
//adapter.addAll(itemslist);
//listView.setAdapter(adapter);
adapter=new CartItemAdapter(context,itemslist);
recyclerView.setAdapter(adapter);
//total=((CartItemAdapter) adapter).getTotal();
if(result!=null)
{
Toast.makeText(CartActivity.this, "Items Fetched successfully", Toast.LENGTH_LONG).show();
}else{
// If username and password does not match display a error message
Toast.makeText(CartActivity.this, "Fetch Failed.", Toast.LENGTH_LONG).show();
}
total=((CartItemAdapter)adapter).grandTotal(itemslist);
CartActivity.total_text.setText(String.valueOf(total));
oids=((CartItemAdapter)adapter).return_oids();
placeorder.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//String url="https://inamtginamtg.000webhostapp.com/currentorders.php";
String url=LoginActivity.weburl+"currentorders.php";
Uri.Builder builder = new Uri.Builder()
.appendQueryParameter("oids", oids);
String query = builder.build().getEncodedQuery();
Log.i("items to current orders",query);
//Toast.makeText(context,"Item removed Successfully..!",Toast.LENGTH_SHORT);
Async_Task a=new Async_Task(context,url,query,true);
a.execute();
String r=a.getResult();
Intent i=new Intent(context,CurrentOrder.class);
startActivity(i);
}
});
AsyncGet1 a1=new AsyncGet1();
a1.execute();
}
String getjsonString()
{
return results;
}
}
public class AsyncGet1 extends AsyncTask<String, String, String> //ERROR Here
{
ProgressDialog pdLoading = new ProgressDialog(CartActivity.this);
HttpURLConnection conn;
URL url = null;
String results="";
@Override
protected void onPreExecute() {
super.onPreExecute();
pdLoading.setMessage("\tLoading...");
pdLoading.setCancelable(false);
pdLoading.show();
}
@Override
protected String doInBackground(String... params) {
try {
// url = new URL("https://inamtginamtg.000webhostapp.com/showcart.php?email="+email);
url = new URL(LoginActivity.weburl+"cartsuggestions.php?email="+email);
Log.i("url1",url.toString());
} catch (MalformedURLException e) {
e.printStackTrace();
return "exception";
}
try {
conn = (HttpURLConnection)url.openConnection();
conn.setReadTimeout(READ_TIMEOUT);
conn.setConnectTimeout(CONNECTION_TIMEOUT);
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.setDoOutput(true);
Log.i("url2",url.toString());
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
writer.write(url.toString());
writer.flush();
writer.close();
os.close();
conn.connect();
} catch (IOException e1) {
e1.printStackTrace();
return "exception";
}
try {
int response_code = conn.getResponseCode();
InputStream input = conn.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(input));
StringBuilder result = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
result.append(line);
}
results=result.toString();
response=results;
Log.i("result",results);
return(result.toString());
}
catch (IOException e) {
e.printStackTrace();
return "exception";
} finally {
conn.disconnect();
}
}
@Override
protected void onPostExecute(String result) {
pdLoading.dismiss();
JSONArray jsonArray = null;
try {
jsonArray = new JSONArray(response);
} catch (JSONException e) {
e.printStackTrace();
}
ArrayList<MenuItemDataModel> itemslist = MenuItemDataModel.fromJson(jsonArray); // ERROR HERE
//CartAdapter adapter = new CartAdapter(CartActivity.this, itemslist);
//adapter.addAll(itemslist);
//listView.setAdapter(adapter);
//data=MenuItemDataModel.fromJson(jsonArray);
adapter1 = new MenuItemAdapterCart(context, itemslist);
recyclerView1.setAdapter(adapter1);
if (result != null) {
Toast.makeText(CartActivity.this, "Items Fetched successfully", Toast.LENGTH_LONG).show();
} else {
// If username and password does not match display a error message
Toast.makeText(CartActivity.this, "Fetch Failed.", Toast.LENGTH_LONG).show();
}
}
}
}
Thanks in advance for the help
