Android error java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener

Question

I am trying to build a simple list view application, but I keep getting this annoying error. I am fairly new to Android so I really don't know how to fix it. Any help is appreciated.

The Error line is here in BirthdayReminderActivity.java:

listView.setOnItemClickListener(new OnItemClickListener() {

Logcat error output is :

   --------- beginning of crash
   E/AndroidRuntime: FATAL EXCEPTION: main
              Process: premprakash.birthdayreminder, PID: 2266
              java.lang.RuntimeException: Unable to start activity    ComponentInfo{premprakash.birthdayreminder/premprakash.birthdayreminder.BirthdayReminderActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
                  at android.app.ActivityThread.-wrap12(ActivityThread.java)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:154)
                  at android.app.ActivityThread.main(ActivityThread.java:6077)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener(android.widget.AdapterView$OnItemClickListener)' on a null object reference
                  at premprakash.birthdayreminder.BirthdayReminderActivity.onCreate(BirthdayReminderActivity.java:51)
                  at android.app.Activity.performCreate(Activity.java:6662)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
                  at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                  at android.os.Looper.loop(Looper.java:154) 
                  at android.app.ActivityThread.main(ActivityThread.java:6077) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

 Application terminated.

BirthdayReminderActivity.java

package premprakash.birthdayreminder;

import android.content.Intent;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.Gravity;

import android.view.View;

import android.widget.Button;

import android.widget.Toast;

import android.widget.AdapterView;

import android.os.Handler;

import android.util.Log;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.ListView;


public class BirthdayReminderActivity extends AppCompatActivity {

private CustomCursorAdapterBirthday customAdapter;
private BirthdayDatabaseHelper databaseHelper;
private static final int ENTER_BIRTHDAY_REQUEST_CODE = 1;
private ListView listView;

private static final String TAG = BirthdayReminderActivity.class.getSimpleName();

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

    Button add = (Button) findViewById(R.id.add);


    databaseHelper = new BirthdayDatabaseHelper(this);

    listView = (ListView) findViewById(R.id.list_birthday);


    listView.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Log.d(TAG, "clicked on item: " + position);
        }
    });

    // Database query can be a time consuming task ..
    // so its safe to call database query in another thread
    // Handler, will handle this stuff for you <img src="http://s0.wp.com/wp-includes/images/smilies/icon_smile.gif?m=1129645325g" alt=":)" class="wp-smiley">

    new Handler().post(new Runnable() {
        @Override
        public void run() {
            customAdapter = new CustomCursorAdapterBirthday(BirthdayReminderActivity.this, databaseHelper.getAllBirthday());

            System.out.println("dsafjkdsjflkdsjfkdsjf");
            listView.setAdapter(customAdapter);
        }
    });

}

public void onClickAdd(View add) {

    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast toast = Toast.makeText(getApplicationContext(), "Successfully Added", Toast.LENGTH_SHORT);
            toast.setGravity(Gravity.BOTTOM, 0, 0);
            toast.show();
            startActivity(new Intent(BirthdayReminderActivity.this, ReminderTypesActivity.class));
        }
    });
}


@Override
protected void onActivityResult(int requestCode, int resultCode, Intent birthday) {

    super.onActivityResult(requestCode, resultCode, birthday);

    if (requestCode == ENTER_BIRTHDAY_REQUEST_CODE && resultCode == RESULT_OK) {

        databaseHelper.insertBirthday(birthday.getExtras().getString("tag_name"), birthday.getExtras().getString("tag_date"), birthday.getExtras().getString("tag_setalarm"), birthday.getExtras().getString("tag_date1"), birthday.getExtras().getString("tag_time"));

        customAdapter.changeCursor(databaseHelper.getAllBirthday());
       }
     }
   }

birthdayreminderactivity.xml

<?xml version="1.0" encoding="utf-8"?>     

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_birthday_reminder"
android:layout_width="match_parent"
android:layout_height="match_parent"
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="premprakash.birthdayreminder.BirthdayReminderActivity">

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:id="@+id/add"
    android:visibility="visible"
    android:contextClickable="true"
    tools:text="@string/add"
    android:onClick="onClickAdd"
    tools:ignore="UnusedAttribute" />

<SearchView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentBottom="true"
    android:layout_toRightOf="@+id/add"
    android:layout_alignTop="@+id/add"
    android:id="@+id/search"
    android:orientation="vertical"
    android:filterTouchesWhenObscured="false"
    android:focusableInTouchMode="true"
    tools:focusableInTouchMode="false"
    android:clickable="true"
    tools:ignore="RtlHardcoded" />

<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:ignore="NestedScrolling"
    android:id="@+id/list_birthday"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

 </RelativeLayout>

manifest.xml

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

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".BirthdayReminderActivity">
        <intent-filter>
            <action android:name="android.intent.action.BIRTHDAYREMINDER" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".ReminderTypesActivity">
        <intent-filter>
            <action android:name="android.intent.action.REMINDERTYPES" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".BirthdayFormActivity">
        <intent-filter>
            <action android:name="android.intent.action.BIRTHDAYFORM" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".AnniversaryFormActivity">
        <intent-filter>
            <action android:name="android.intent.action.ANNIVERSARYFORM" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

    <activity android:name=".OthersFormActivity">
        <intent-filter>
            <action android:name="android.intent.action.OTHERSFORM" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>

CustomCursorAdapterBirthday.java

package premprakash.birthdayreminder;

import android.content.Context;
import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CursorAdapter;
import android.widget.TextView;


public class CustomCursorAdapterBirthday extends CursorAdapter {

public CustomCursorAdapterBirthday(Context context, Cursor c) {
    super(context, c);
}

@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    // when the view will be created for first time,
    // we need to tell the adapters, how each item will look
    LayoutInflater inflater = LayoutInflater.from(parent.getContext());
    View retView = inflater.inflate(R.layout.activity_birthday_reminder, parent, false);

    return retView;
  }

@Override
public void bindView(View view, Context context, Cursor cursor) {
    // here we are setting our data
    // that means, take the data from the cursor and put it in views

    TextView textViewName = (TextView) view.findViewById(R.id.name);
    textViewName.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(1))));

    TextView textViewDate = (TextView) view.findViewById(R.id.date);
    textViewDate.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(2))));

    TextView textViewSetalarm = (TextView) view.findViewById(R.id.setalarm);
    textViewSetalarm.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(3))));

    TextView textViewDate1 = (TextView) view.findViewById(R.id.date);
    textViewDate1.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(4))));

    TextView textViewTime = (TextView) view.findViewById(R.id.time);
    textViewTime.setText(cursor.getString(cursor.getColumnIndex(cursor.getColumnName(5))));

   }
}

BirthdayDatabaseHelper.java

 package premprakash.birthdayreminder;


 import android.content.ContentValues;
 import android.content.Context;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.util.Log;

 public class BirthdayDatabaseHelper {

 private static final String TAG = BirthdayDatabaseHelper.class.getSimpleName();

 // database configuration
 // if you want the onUpgrade to run then change the database_version
 private static final int DATABASE_VERSION = 4;
 private static final String DATABASE_NAME = "birthdaydatabase.db";

// table configuration
private static final String TABLE_NAME = "birthday";         // Table name
private static final String BIRTHDAY_TABLE_COLUMN_ID = "_id";     // a column named "_id" is required for cursor
private static final String BIRTHDAY_TABLE_COLUMN_NAME = "name";
private static final String BIRTHDAY_TABLE_COLUMN_DATE = "date";
private static final String BIRTHDAY_TABLE_COLUMN_SETALARM = "setalarm";
private static final String BIRTHDAY_TABLE_COLUMN_DATE1 = "date1";
private static final String BIRTHDAY_TABLE_COLUMN_TIME = "time";

private DatabaseOpenHelper openHelper;
private SQLiteDatabase database;

// this is a wrapper class. that means, from outside world, anyone will communicate with PersonDatabaseHelper,
// but under the hood actually DatabaseOpenHelper class will perform database CRUD operations
public BirthdayDatabaseHelper(Context Context) {

    openHelper = new DatabaseOpenHelper(Context);
    database = openHelper.getWritableDatabase();
 }

 public void insertBirthday (String Name, String Date, String Setalarm, String Date1, String Time) {

    // we are using ContentValues to avoid sql format errors

    ContentValues contentValues = new ContentValues();

    contentValues.put(BIRTHDAY_TABLE_COLUMN_NAME, Name);
    contentValues.put(BIRTHDAY_TABLE_COLUMN_DATE, Date);
    contentValues.put(BIRTHDAY_TABLE_COLUMN_SETALARM, Setalarm);
    contentValues.put(BIRTHDAY_TABLE_COLUMN_DATE1, Date1);
    contentValues.put(BIRTHDAY_TABLE_COLUMN_TIME, Time);

    database.insert(TABLE_NAME, null, contentValues);
  }

  public Cursor getAllBirthday () {

    String buildSQL = "SELECT * FROM " + TABLE_NAME;

    Log.d(TAG, "getAllBirthday SQL: " + buildSQL);

    System.out.println("HKJHDSFKJDhf");

    return database.rawQuery(buildSQL, null);
   }

// this DatabaseOpenHelper class will actually be used to perform database related operation

 private class DatabaseOpenHelper extends SQLiteOpenHelper {

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

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        // Create your tables here

        String buildSQL = "CREATE TABLE " + TABLE_NAME + "( " + BIRTHDAY_TABLE_COLUMN_ID + " INTEGER PRIMARY KEY, " + BIRTHDAY_TABLE_COLUMN_NAME + " TEXT, " + BIRTHDAY_TABLE_COLUMN_DATE + " TEXT, " + BIRTHDAY_TABLE_COLUMN_SETALARM + " TEXT, " + BIRTHDAY_TABLE_COLUMN_DATE1 + " TEXT, " + BIRTHDAY_TABLE_COLUMN_TIME + " TEXT )";

        Log.d(TAG, "onCreate SQL: " + buildSQL);

        sqLiteDatabase.execSQL(buildSQL);
     }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
        // Database schema upgrade code goes here

        String buildSQL = "DROP TABLE IF EXISTS " + TABLE_NAME;

        Log.d(TAG, "onUpgrade SQL: " + buildSQL);

        sqLiteDatabase.execSQL(buildSQL);       // drop previous table

        onCreate(sqLiteDatabase);               // create the table from the beginning
        }
     }
  }

**R.layout.activity_birthday_reminder != birthdayreminderactivity.xml** — Prerak Sola, Jan 06 '17 at 15:42

score 0 · Answer 1 · answered Jan 06 '17 at 15:43

That's a standard Null Pointer Exception i.e. you're trying to access an object that doesn't exist. In your case, your activity has not been able to find your ListView, so findViewById has returned a null object.

I suspect this line is the problem in BirthdayReminderActivity.java:

setContentView(R.layout.activity_birthday_reminder);

It's a different name to the xml file you provided (birthdayreminderactivity.xml), so your activity is instead inflating a file called activity_birthday_reminder. Try changing it to:

setContentView(R.layout.birthdayreminderactivity);

score 0 · Answer 2 · answered Jan 06 '17 at 15:44

0

You are setting your contentview with the id of the linearlayout instead of the layout file name

 setContentView(R.layout.birthdayreminderactivity);

answered Jan 06 '17 at 15:44

Pablo Cegarra

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Android error java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setOnItemClickListener

2 Answers2