Member Avatar for Saboor880

Hi to all! I made a class named “Database” I called openOrCreateDatabase in in its constructor but it was giving error.
Then I searched on internet and got a solution that in case of non activity class I should also pass context. Then I passed context but then I am facing an error in run time in LogCat: ”java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase android.content.Context.openOrCreateDatabase(java.lang.String, int, android.database.sqlite.SQLiteDatabase$CursorFactory)' on a null object reference."

Above in the double quotes is the error.please guide me
Actually I want that I just call the constructor of this class in another class named “InsertRecord” and the database should be created. Now i am pasting code of both my classes

package com.hatflabs.addressbook;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.support.design.widget.TabLayout;
import android.text.Editable;
import android.util.Log;
import android.view.LayoutInflater;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import javax.xml.parsers.FactoryConfigurationError;

/**
 * Created by applezone on 1/1/01.
 */
public class Database  {

    SQLiteDatabase db;
    Connection con;
    String dbName = "MyDb";

    // constructor
    public Database(Context ctxt,  SQLiteDatabase db) {
        db = ctxt.openOrCreateDatabase(dbName, ctxt.MODE_PRIVATE,null);

    }

}

Now I am code of InsertRecord class

package com.hatflabs.addressbook;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.hatflabs.addressbook.Database.*;

import java.sql.PreparedStatement;

public class InsertRecord extends AppCompatActivity {

    Context ctxt;
    SQLiteDatabase db;
    Button b1;

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

        b1 = (Button)findViewById(R.id.button1);

        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

           //creating object of Database class

           Database dtbs = new Database(ctxt,db );
                Log.w("Saboor","database created");

            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_insert_record, 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);
    }
}
  • 2 Contributors
  • 1 Reply
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  • 3 Days Discussion Span
  • Latest Post Latest Post by rproffitt

Dani AI

Generated

You are getting the NPE because the Context you pass in is null. In InsertRecord, the field ctxt is never initialized, so new Database(ctxt, db) dereferences a null context. There is also variable shadowing in your Database constructor: the parameter named db hides the class field, so you never actually assign to this.db. Finally, the java.sql.* imports are not used for Android SQLite and can be removed.

Quick, minimal fix:

  • Pass a non-null context from your Activity (e.g., InsertRecord.this or getApplicationContext()).
  • Do not take SQLiteDatabase as a constructor parameter; create and store it inside your class.
  • Assign to the field, not a shadowed parameter.

Example:

public final class Database {
    private static final String DB_NAME = "MyDb.db";
    private final SQLiteDatabase db;

    public Database(Context context) {
        this.db = context.openOrCreateDatabase(DB_NAME, Context.MODE_PRIVATE, null);
        // TODO: create tables if needed with db.execSQL(...)
    }

    public SQLiteDatabase getDb() { return db; }
}

And from your Activity click handler:

Database dtbs = new Database(InsertRecord.this); // or getApplicationContext()

Better long-term: follow Android’s recommended pattern with SQLiteOpenHelper. Put your schema in onCreate, upgrades in onUpgrade, and call getWritableDatabase() when you need a handle. This avoids lifecycle leaks, handles versioning, and centralizes DB setup.

Debugging tip echoing : set a breakpoint where you construct Database and inspect the Context, or log/Toast context == null. Also log the DB path with db.getPath() after opening so you know it actually opened. Remove java.sql.Connection/PreparedStatement; use SQLiteDatabase and SQLiteStatement on Android.

Member Avatar for rproffitt

This is not the answer but to share how I debug such a thing. I hook up my device and run it over the Android studio USB debugger and break at that line of code to examine variables to see what's up. If I can't do that I've been sending up "toasts" with messages so I can see what's going on inside.

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