unable to insert data into database using SQLite, getting null pointer exception

Question

I have two activity class. one have a floating button and the other have a simple button. somehow , when i am getting error while running the insert query. The error i got was :

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.sidharth.android.navigationdrawer.controller.DatabaseHelper.insertNote(java.lang.String, java.lang.String)' on a null object reference

at com.sidharth.android.navigationdrawer.view.CreateNoteActivity.insert(CreateNoteActivity.java:60)

MainActivity.java

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;

import com.sidharth.android.navigationdrawer.R;

public class  MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, CreateNoteActivity.class);
                startActivity(intent);

            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @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;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_camera) {
            // Handle the camera action
        } else if (id == R.id.nav_gallery) {

        } else if (id == R.id.nav_slideshow) {

        } else if (id == R.id.nav_manage) {

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}

CreateNoteActivity.java

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

import com.sidharth.android.navigationdrawer.R;
import com.sidharth.android.navigationdrawer.controller.DatabaseHelper;

public class CreateNoteActivity extends AppCompatActivity {

    EditText noteTitle;
    EditText noteContent;
    Button btnSav;

    DatabaseHelper db ;
    private String title ;
    private String content ;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.note_dialog);

       /* Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);*/

        noteTitle = (EditText) findViewById(R.id.dialog_title);
        Log.d("noteTitle first",noteTitle+"");

        noteContent = (EditText) findViewById(R.id.note);
        Log.d("noteContent first",noteContent+"");

        btnSav = (Button) findViewById(R.id.btnSave);
        btnSav.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                title = noteTitle.getText().toString();
                content = noteContent.getText().toString();

                Log.d("Title inside button",title+"");
                Log.d("Content inside button",content+"");
                insert(title,content);

            }
        });
    }

    public void insert(String title, String content){
        Log.d("title before insert ", title);
        Log.d("content before insert ", content);
        db.insertNote(title,content);

        Log.d("note id - ", "");
        Log.d("title inside insert ", title);
        Log.d("content inside insert ", content);
        //Log.d("return from insert ",id+"");
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />

</android.support.v4.widget.DrawerLayout>

app_bar_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".view.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>


    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

note_dialog.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_margin"
    android:paddingRight="@dimen/activity_margin"
    android:paddingTop="@dimen/activity_margin">

    <EditText android:id="@+id/dialog_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="@dimen/dimen_10"
        android:fontFamily="sans-serif-medium"
        android:lineSpacingExtra="8sp"
        android:hint="@string/lbl_new_note_title"
        android:textColor="@color/colorAccent"
        android:textSize="@dimen/lbl_new_note_title"
        android:textStyle="normal" />

    <EditText
        android:id="@+id/note"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="@dimen/dimen_10"
        android:background="@android:color/transparent"
        android:gravity="top"
        android:hint="@string/hint_enter_note"
        android:inputType="textCapSentences|textMultiLine"
        android:lines="4"
        android:textColorHint="@color/hint_enter_note"
        android:textSize="@dimen/input_new_note" />

    <Button
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        android:text="save" />


</LinearLayout>

AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.sidharth.android.navigationdrawer">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".view.MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".view.CreateNoteActivity"></activity>
    </application>

</manifest>

Note.java

public class Note {

    //table name
    public static final String TABLE_NAME = "notes";

    //column name
    public static final String COLUMN_ID = "id";
    public static final String COLUMN_TITLE = "title";
    public static final String COLUMN_CONTENT = "content";

    //pojo class
    private int id;
    private String title;
    private String content;

    public static final String CREATE_TABLE = "CREATE TABLE " +TABLE_NAME + "("
            + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
            + COLUMN_TITLE + " TEXT, "
            + COLUMN_CONTENT + " TEXT " + ");" ;

    public Note() {
    }

    public Note(int id, String title, String content) {
        this.id = id;
        this.title = title;
        this.content = content;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

DatabaseHelper.java

public void insertNote(String title, String content){
        Log.d("inside insert method ", " hiiii ");
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();

        values.put(Note.COLUMN_TITLE,title);
        values.put(Note.COLUMN_CONTENT,content);

        db.insert(Note.TABLE_NAME,null,values);
        db.close();
        //Log.d("id in insert", id+"");
        //return id;
    }

meaning ? where i have intialized what ?? please elaborate a little. — Sidharth K.Burnwal, Jun 06 '18 at 17:56
i gave you the whole line of code to write, you need to elaborate me more? just initialize the object with new instance with the code line i gave — Masoom Badi, Jun 06 '18 at 17:59

devmike01 · Answer 1 · 2018-06-06T18:02:21.553

0

The reason why you're getting that error is because you're trying to access class that the activity doesn't know about. To make your activity aware of the POJO class, simply initialize Note POJO in your onCreate() method. Like this:

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.note_dialog);

         //Initialize Note pojo
         note = new Note();
         ...

Note: Make sure you initialize the pojo properly before using it.

edited Jun 06 '18 at 18:02

answered Jun 06 '18 at 17:57

devmike01

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tried, still the app getting stopped just after clicking on floating button. – Sidharth K.Burnwal Jun 06 '18 at 18:01
post your log here – devmike01 Jun 06 '18 at 18:27
i have done that, can u tell me what am i missing while inserting into the database? i am stuck there . – Sidharth K.Burnwal Jun 12 '18 at 17:55
Initialize your `DatabaseHelper` in your `onCreate()` function before calling `insertNote()`. E.g: `db = new DatabaseHelper();` in your `onCreate()` and call insertNote. – devmike01 Jun 29 '18 at 13:03

unable to insert data into database using SQLite, getting null pointer exception

1 Answers1