Application stops unexpectedly in emulator because of Fatal exception - json

Question

I have got log in and register screen for android app and the activities associated with them when the register or log in buttons are clicked. I dont get any errors while saving it.
But when I run it, the screen loads up in emulator, allows me to enter data, but as soon as I click on Register button or Login button, I get error "Application Stopped Unexpectedly, Please try again ".
Following is the error that I get in LogCat:
03-01 13:01:49.649: W/dalvikvm(583): threadid=1: thread exiting with uncaught exception (group=0x40015560)
03-01 13:01:49.669: E/AndroidRuntime(583): FATAL EXCEPTION: main
03-01 13:01:49.669: E/AndroidRuntime(583): java.lang.NullPointerException
03-01 13:01:49.669: E/AndroidRuntime(583): at com.example.attendance2.RegisterActivity$1.onClick(RegisterActivity.java:59)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.view.View.performClick(View.java:2485)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.view.View$PerformClick.run(View.java:9080)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Handler.handleCallback(Handler.java:587)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Handler.dispatchMessage(Handler.java:92)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.os.Looper.loop(Looper.java:123)
03-01 13:01:49.669: E/AndroidRuntime(583): at android.app.ActivityThread.main(ActivityThread.java:3683)
03-01 13:01:49.669: E/AndroidRuntime(583): at java.lang.reflect.Method.invokeNative(Native Method)
03-01 13:01:49.669: E/AndroidRuntime(583): at java.lang.reflect.Method.invoke(Method.java:507)
03-01 13:01:49.669: E/AndroidRuntime(583): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-01 13:01:49.669: E/AndroidRuntime(583): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-01 13:01:49.669: E/AndroidRuntime(583): at dalvik.system.NativeStart.main(Native Method)
03-01 13:01:56.080: I/Process(583): Sending signal. PID: 583 SIG: 9
I have checked RegisterActivity.java and it seems all good in that...
I have also added RegisterActivity.java and UserFunctions.java
Please let me know if you find whats the problem is and also if more coding is required!
The same sort of error occurs when I try LoginActivity.java for my login.
RegisterActivity.java
package com.example.attendance2;
import org.json.JSONException;
import org.json.JSONObject;
import library.DatabaseHandler;
import library.UserFunctions;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class RegisterActivity extends Activity {
Button btnRegister;
Button btnLinkToLogin;
EditText inputFullName;
EditText inputEmail;
EditText inputPassword;
TextView registerErrorMsg;
// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.register);
// Importing all assets like buttons, text fields
inputFullName = (EditText) findViewById(R.id.registerName);
inputEmail = (EditText) findViewById(R.id.registerEmail);
inputPassword = (EditText) findViewById(R.id.registerPassword);
btnRegister = (Button) findViewById(R.id.btnRegister);
btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
registerErrorMsg = (TextView) findViewById(R.id.register_error);
// Register Button Click event
btnRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String name = inputFullName.getText().toString();
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
UserFunctions userFunction = new UserFunctions();
JSONObject json = userFunction.registerUser(name, email, password);
// check for login response
try {
if (json.getString(KEY_SUCCESS) != null) {
registerErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
// user successfully registered
// Store user details in SQLite Database
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
// Clear all previous data in database
userFunction.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));
// Launch Dashboard Screen
Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
// Close all views before launching Dashboard
dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(dashboard);
// Close Registration Screen
finish();
}else{
// Error in registration
registerErrorMsg.setText("Error occured in registration");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
// Link to Login Screen
btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
LoginActivity.class);
startActivity(i);
// Close Registration View
finish();
}
});
}
}
UserFunctions.java
package library;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.jsn.JSONObject;
import android.content.Context;
public class UserFunctions {
private JSONParser jsonParser;
// Testing in localhost using wamp or xampp
// use http://10.0.2.2/ to connect to your localhost ie http://localhost/
private static String loginURL = "http://10.0.2.2:82/android_api/";
private static String registerURL = "http://10.0.2.2:82/android_api/";
private static String login_tag = "login";
private static String register_tag = "register";
// constructor
public UserFunctions(){
jsonParser = new JSONParser();
}
/**
* function make Login Request
* #param email
* #param password
* */
public JSONObject loginUser(String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", login_tag));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
// return json
// Log.e("JSON", json.toString());
return json;
}
/**
* function make Login Request
* #param name
* #param email
* #param password
* */
public JSONObject registerUser(String name, String email, String password){
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("tag", register_tag));
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("email", email));
params.add(new BasicNameValuePair("password", password));
// getting JSON Object
JSONObject json = jsonParser.getJSONFromUrl(registerURL, params);
// return json
return json;
}
/**
* Function get Login status
* */
public boolean isUserLoggedIn(Context context){
DatabaseHandler db = new DatabaseHandler(context);
int count = db.getRowCount();
if(count > 0){
// user logged in
return true;
}
return false;
}
/**
* Function to logout user
* Reset Database
* */
public boolean logoutUser(Context context){
DatabaseHandler db = new DatabaseHandler(context);
db.resetTables();
return true;
}
}

Answer 1

It looks to me, like registerErrorMsg is null - e.g. your text view is not found in the layout. It is possible, that the id you use (R.id.register_error) is declared in another element.