ERROR: Android Runtime : FATAL EXCEPTION java.lang.RuntimeException

Question

I am getting this Error:

05-09 23:34:04.251 21214-21214/com.example.averm.phonecontact E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.averm.phonecontact, PID: 21214
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.averm.phonecontact/com.example.averm.phonecontact.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.example.averm.phonecontact.DatabaseHandler.getContactsCount()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2335)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2397)
    at android.app.ActivityThread.access$800(ActivityThread.java:151)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5268)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.example.averm.phonecontact.DatabaseHandler.getContactsCount()' on a null object reference
    at com.example.averm.phonecontact.MainActivity.onCreate(MainActivity.java:106)
    at android.app.Activity.performCreate(Activity.java:6033)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2288)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2397) 
    at android.app.ActivityThread.access$800(ActivityThread.java:151) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:135) 
    at android.app.ActivityThread.main(ActivityThread.java:5268) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:372) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)

My Code is:

MainActivity.java Class :

public class MainActivity extends AppCompatActivity {

    private EditText nameTxt, phoneTxt, emailTxt, addressTxt;
    ImageView contactImageImgView;
    List<Contact> Contacts = new ArrayList<Contact>();
    ListView contactListView;
    Uri imageUri = Uri.parse("android.resource://org.intracode.contactmanager/drawable/no_user_logo.png");
    DatabaseHandler dbHandler;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        nameTxt = (EditText)findViewById(R.id.edName);
        phoneTxt = (EditText)findViewById(R.id.edNumber);
        emailTxt = (EditText)findViewById(R.id.edEmail);
        addressTxt = (EditText)findViewById(R.id.edAddress);
        contactListView = (ListView)findViewById(R.id.listView);
        contactImageImgView = (ImageView)findViewById(R.id.imgViewContactImage);


        TabHost tabHost = (TabHost)findViewById(R.id.tabHost);
        tabHost.setup();
        TabHost.TabSpec tabSpec = tabHost.newTabSpec("creator");
        tabSpec.setContent(R.id.tabCreator);
        tabSpec.setIndicator("Creator");
        tabHost.addTab(tabSpec);

        tabSpec = tabHost.newTabSpec("List");
        tabSpec.setContent(R.id.tabContactList);
        tabSpec.setIndicator("List");
        tabHost.addTab(tabSpec);


        final Button addBtn = (Button)findViewById(R.id.btnAdd);

        addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Contact contact = new Contact(dbHandler.getContactsCount(), String.valueOf(nameTxt.getText()), String.valueOf(phoneTxt.getText()),
                        String.valueOf(emailTxt.getText()), String.valueOf(addressTxt.getText()), imageUri);
                if (!contactExists(contact)){
                    dbHandler.createContact(contact);
                    Contacts.add(contact);
                    Toast.makeText(getApplicationContext(),String.valueOf(nameTxt.getText()) +" has been added to your Contacts!", Toast.LENGTH_SHORT).show();
                    return;
                }
                Toast.makeText(getApplicationContext(), String.valueOf(nameTxt.getText()) + " already exists. Please use a different name.", Toast.LENGTH_SHORT).show();
            }
        });

        nameTxt.addTextChangedListener(new TextWatcher() {

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                addBtn.setEnabled(String.valueOf(nameTxt.getText()).trim().length() > 0);
            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

        contactImageImgView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setType("image/*");
                intent.setAction(Intent.ACTION_GET_CONTENT);
                startActivityForResult(Intent.createChooser(intent, "Select Contact Image"), 1);
            }
        });

        if (dbHandler.getContactsCount() != 0)
            Contacts.addAll(dbHandler.getAllContacts());
        populateList();

    }

    public void onActivityResult(int reqCode, int resCode, Intent data){
        if (resCode == RESULT_OK){
            if (reqCode == 1){
                imageUri = data.getData();
                contactImageImgView.setImageURI(imageUri);
            }
        }
    }

    private boolean contactExists(Contact contact) {
        String name = contact.getName();
        int contactCount = Contacts.size();
        for (int i = 0; i < contactCount; i++) {
            if (name.compareToIgnoreCase(Contacts.get(i).getName()) == 0)
                return true;
        }
        return false;
    }



    private void populateList(){
        ArrayAdapter<Contact> adaptor= new ContactListAdaptor();
        contactListView.setAdapter(adaptor);

    }


    private class ContactListAdaptor extends ArrayAdapter<Contact>{
        public ContactListAdaptor(){
            super(MainActivity.this,R.layout.listview_item, Contacts);
        }

        @Override
        public View getView(int position, View view, ViewGroup parent){
            if(view == null)
                view = getLayoutInflater().inflate(R.layout.listview_item, parent, false);

            Contact currentContact = Contacts.get(position);

            TextView name = (TextView) view.findViewById(R.id.contactName);
            name.setText(currentContact.getName());
            TextView phone = (TextView) view.findViewById(R.id.phoneNumber);
            phone.setText(currentContact.getPhone());
            TextView email = (TextView) view.findViewById(R.id.emailAddress);
            email.setText(currentContact.getEmail());
            TextView address = (TextView) view.findViewById(R.id.cAddress);
            address.setText(currentContact.getAddress());
            ImageView ivContactImage = (ImageView) view.findViewById(R.id.ivContactImage);
            ivContactImage.setImageURI(currentContact.getImageURI());
            return view;
        }
    }
}

DatabaseHandler.java Class:

public class DatabaseHandler extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 2;
    private static final String DATABASE_NAME = "contactManager",
            TABLE_CONTACTS = "contacts",
            KEY_ID = "id",
            KEY_NAME = "name",
            KEY_PHONE = "phone",
            KEY_EMAIL = "email",
            KEY_ADDRESS = "address",
            KEY_IMAGEURI = "imageUri";

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + TABLE_CONTACTS + "(" + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT," + KEY_PHONE + " TEXT," + KEY_EMAIL + " TEXT," + KEY_ADDRESS + " TEXT," + KEY_IMAGEURI + " TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
        onCreate(db);
    }

    public void createContact(Contact contact) {
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(KEY_NAME, contact.getName());
        values.put(KEY_PHONE, contact.getPhone());
        values.put(KEY_EMAIL, contact.getEmail());
        values.put(KEY_ADDRESS, contact.getAddress());
        values.put(KEY_IMAGEURI, contact.getImageURI().toString());
        db.insert(TABLE_CONTACTS, null, values);
        db.close();
    }

    public Contact getContact(int id) {
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID, KEY_NAME, KEY_PHONE, KEY_EMAIL, KEY_ADDRESS, KEY_IMAGEURI }, KEY_ID + "=?", new String[] { String.valueOf(id) }, null, null, null, null );
        if (cursor != null)
            cursor.moveToFirst();
        Contact contact = new Contact(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2), cursor.getString(3), cursor.getString(4), Uri.parse(cursor.getString(5)));
        db.close();
        cursor.close();
        return contact;
    }



    public int getContactsCount() {
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_CONTACTS, null);
        int count = cursor.getCount();
        db.close();
        cursor.close();
        return count;
    }
}

You do `if (dbHandler.getContactsCount() != 0)` but never set `dbHandler` so it's null and you get a NPE — , May 09 '16 at 18:17

score 0 · Answer 1 · answered May 09 '16 at 18:20

0

You have a dbHandler field. You never call dbHandler=new DatabaseHandler(this) in onCreate(), and therefore dbHandler is null.

Also, please do database I/O on background threads.

answered May 09 '16 at 18:20

CommonsWare

986,068
189
2,389
2,491

Thank you :) Problem Solved – ashish verma May 09 '16 at 18:36

score 0 · Accepted Answer · answered May 09 '16 at 18:22

0

You have created the instance the DatabaseHandler but never initialized it with any value. You have to create the object of the class and then use it to access the methods.In onCreate of your activity add the below code

DatabaseHandler dbHandler=new DatabaseHandler(this)

answered May 09 '16 at 18:22

Gautam

3,252
3
23
32

Thank you :) Problem Solved. – ashish verma May 09 '16 at 18:35

ERROR: Android Runtime : FATAL EXCEPTION java.lang.RuntimeException

2 Answers2