I get a NullPointerException, but I don't know where the error is

Question

The logcat is here:

list view activity --> clicked item(admin_parents_item) ---> option selected EDIT (current activity)

When I click on my button to update/edit the database it crashes. Something is missing. How to fix this error?

03-08 06:44:57.163 11022-11022/edu.angelo.parentsportal E/AndroidRuntime: FATAL EXCEPTION: main
Process: edu.angelo.parentsportal, PID: 11022
java.lang.NullPointerException: Attempt to invoke virtual method 'void edu.angelo.parentsportal.DatabaseHelper.updateData(int, java.lang.String, java.lang.String, java.lang.String, java.lang.String, java.lang.String)' on a null object reference
    at edu.angelo.parentsportal.Admin_Parents_Item_Edit$1.onClick(Admin_Parents_Item_Edit.java:63)
    at android.view.View.performClick(View.java:4780)
    at android.view.View$PerformClick.run(View.java:19866)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5254)
    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:903)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

admin_parent__item_edit.java (my current activity)

package edu.angelo.parentsportal;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class Admin_Parents_Item_Edit extends AppCompatActivity {

    Button btn_update;

    EditText ed_Name;
    EditText ed_Surname;
    EditText ed_Email;
    EditText ed_Phone_Number;
    EditText ed_Password;

    String s_Id;
    String s_Name;
    String s_Surname;
    String s_Email;
    String s_Phone_Number;
    String s_Password;

    Integer getId;

    DatabaseHelper databaseHelper;

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

        ed_Name = findViewById(R.id.ed_name_update);
        ed_Surname = findViewById(R.id.ed_surname_update);
        ed_Email = findViewById(R.id.ed_email_update);
        ed_Phone_Number = findViewById(R.id.ed_PhoneNumber_update);
        ed_Password = findViewById(R.id.ed_password_update);

        Intent intent = getIntent();
        s_Id = intent.getStringExtra("ID");
        s_Name = intent.getStringExtra("Name");
        s_Surname = intent.getStringExtra("Surname");
        s_Email = intent.getStringExtra("Email Address");
        s_Phone_Number = intent.getStringExtra("Phone number");
        s_Password = intent.getStringExtra("Password");

        getId = Integer.parseInt(s_Id);

        ed_Name.setText(s_Name);
        ed_Surname.setText(s_Surname);
        ed_Email.setText(s_Email);
        ed_Phone_Number.setText(s_Phone_Number);
        ed_Password.setText(s_Password);

        btn_update = findViewById(R.id.btn_admin_parent_update);

        btn_update.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                databaseHelper.updateData(getId,
                        ed_Name.getText().toString(),
                        ed_Surname.getText().toString(),
                        ed_Email.getText().toString(),
                        ed_Phone_Number.getText().toString(),
                        ed_Password.getText().toString());
                finish();
            }
        });
    }
}

Admin_parent_Item (my previous activity)

package edu.angelo.parentsportal;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.TextView;

public class Admin_Parents_Item extends AppCompatActivity {
    TextView tv_Id;
    TextView tv_Name;
    TextView tv_Surname;
    TextView tv_Email;
    TextView tv_Phone_Number;
    TextView tv_Password;

    String s_Id;
    String s_Name;
    String s_Surname;
    String s_Email;
    String s_Phone_Number;
    String s_Password;

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

        tv_Id = findViewById(R.id.tv_id_info);
        tv_Name = findViewById(R.id.tv_name_info);
        tv_Surname = findViewById(R.id.tv_surname_info);
        tv_Email = findViewById(R.id.tv_email_info);
        tv_Phone_Number = findViewById(R.id.tv_PhoneNumber_info);
        tv_Password = findViewById(R.id.tv_password_info);

        Intent intent = getIntent();
        if (intent != null) {
            s_Id = intent.getStringExtra("ID");
            s_Name = intent.getStringExtra("Name");
            s_Surname = intent.getStringExtra("Surname");
            s_Email = intent.getStringExtra("Email Address");
            s_Phone_Number = intent.getStringExtra("Phone Number");
            s_Password = intent.getStringExtra("Password");
        }
        tv_Id.setText(s_Id);
        tv_Name.setText(s_Name);
        tv_Surname.setText(s_Surname);
        tv_Email.setText(s_Email);
        tv_Phone_Number.setText(s_Phone_Number);
        tv_Password.setText(s_Password);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.admin__parents_item, 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();
        switch (id) {
            case R.id.admin_parent_item_action_edit: {
                Intent intent = new Intent(this, Admin_Parents_Item_Edit.class);
                intent.putExtra("ID", s_Id);
                intent.putExtra("Name", s_Name);
                intent.putExtra("Surname", s_Surname);
                intent.putExtra("Email Address", s_Email);
                intent.putExtra("Phone number", s_Phone_Number);
                intent.putExtra("Password", s_Password);
                startActivity(intent);
                finish();
                break;
            }
        }
        return super.onOptionsItemSelected(item);
    }
}

DatabaseHelper.java

package edu.angelo.parentsportal;

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

import java.util.ArrayList;

public class DatabaseHelper extends SQLiteOpenHelper {

    public static final String DATABASE_NAME = "Parents_Portal.db";
    public static final String TABLE_NAME = "Parents_Table";
    public static final String COL_0 = "ID";
    public static final String COL_1 = "NAME";
    public static final String COL_2 = "SURNAME";
    public static final String COL_3 = "EMAIL_ADDRESS";
    public static final String COL_4 = "PHONE_NUMBER";
    public static final String COL_5 = "PASSWORD";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TABLE_NAME +"(ID INTEGER PRIMARY KEY
        AUTOINCREMENT, NAME TEXT, SURNAME TEXT, EMAIL_ADDRESS TEXT, PHONE_NUMBER TEXT,
        PASSWORD TEXT)");
    }

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

    public boolean insertData(String name, String surname, String email_address,
        String phone_number, String password) {

        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_1, name);
        contentValues.put(COL_2, surname);
        contentValues.put(COL_3, email_address);
        contentValues.put(COL_4, phone_number);
        contentValues.put(COL_5, password);
        long result = db.insert(TABLE_NAME, null, contentValues);
        if (result == -1) {
            return false;
        }
        else {
            return true;
        }
    }

    public Cursor getAllData() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor result = db.rawQuery("select * from " + TABLE_NAME, null);
        return result;
    }


    public ArrayList<ParentModel> getAllParentsData() {
        ArrayList<ParentModel> list = new ArrayList<>();
        String sql = "select * from " + TABLE_NAME;
        SQLiteDatabase mydb = this.getWritableDatabase();
        Cursor cursor = mydb.rawQuery(sql, null);
        if (cursor.moveToFirst()) {
            do {
                ParentModel parentModel = new ParentModel();
                parentModel.setID(cursor.getString(0));
                parentModel.setName(cursor.getString(1));
                parentModel.setSurname(cursor.getString(2));
                parentModel.setEmail(cursor.getString(3));
                parentModel.setPhone_number(cursor.getString(4));
                parentModel.setPassword(cursor.getString(5));
                list.add(parentModel);
            }
            while (cursor.moveToNext())
                ;
        }
        return list;
    }

    public void updateData(int id, String name, String surname, String email,
                           String phone_number, String password) {

        ContentValues contentValues = new ContentValues();
        String sql = "select * from " + TABLE_NAME;
        SQLiteDatabase mydb = this.getWritableDatabase();
        Cursor cursor = mydb.rawQuery(sql, null);

        if (cursor.moveToFirst()) {
            do {
                contentValues.put(COL_1, name);
                contentValues.put(COL_2, surname);
                contentValues.put(COL_3, email);
                contentValues.put(COL_4, phone_number);
                contentValues.put(COL_5, password);
            }
            while (cursor.moveToNext());
        }
        mydb.update(TABLE_NAME, contentValues, COL_0 + "=" + id, null);
        mydb.close();
    }
}

`databaseHelper` is null. add `databaseHelper =new DatabaseHelper(this)` in onCreate method — ρяσѕρєя K, Mar 08 '19 at 07:01
To help you find the error: Notice your stacktrace says `Attempt to invoke virtual method '...DatabaseHelper.updateData(..)` on a null object reference'. So that means it's trying to call `updateData()` on something that is null. To find the error, ask yourself what object in your code is calling updateData()? That's the thing which is null. The line below tells you the class and line where the error occurred. `Admin_Parents_Item_Edit$1.onClick(Admin_Parents_Item_Edit.java:63)` Line 63. Hope that helps. — MSpeed, Mar 08 '19 at 09:27

score 0 · Answer 1 · edited Mar 08 '19 at 09:04

0

Your databaseHelper is null. Initialize it in onCreate() like below.

DatabaseHelper databaseHelper;

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

    databaseHelper = new DatabaseHelper (this); // Add this line
    .........................

edited Mar 08 '19 at 09:04

Peter Mortensen

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answered Mar 08 '19 at 07:08

Jakir Hossain

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I get a NullPointerException, but I don't know where the error is

1 Answers1