SQLite 데이터베이스 파일의 파일 확장자

<?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"
    tools:context=".MainActivity">

	<Button
        android:layout_width="wrap_content"
    	android:layout_height="wrap_content"
        android:id="@+id/createdb"
        android:text="Create Database">
    </Button>

</LinearLayout>

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
  private Button createDB;
  private DBHandler dbHandler;

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

    createDB = findViewById(R.id.createdb);
    dbHandler = new DBHandler(MainActivity.this);

    createDB.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        dbHandler.addNewEntry("Hello World");

        Toast
            .makeText(MainActivity.this, "A new text has been added to the SQLite database",
                Toast.LENGTH_SHORT)
            .show();
      }
    });
  }
}

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

public class DBHandler extends SQLiteOpenHelper {
  private static final String DB_NAME = "newdb";
  private static final int DB_VERSION = 1;
  private static final String TABLE_NAME = "mytable";

  private static final String ID_COL = "id";
  private static final String WORD = "word";

  public DBHandler(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase db) {
    String query = "CREATE TABLE " + TABLE_NAME + " (" + ID_COL
        + " INTEGER PRIMARY KEY AUTOINCREMENT, " + WORD + " TEXT)";

    db.execSQL(query);
  }

  // this method is used to add a new course to our sqlite database.
  public void addNewCourse(String myword) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();

    values.put(WORD, myword);
    db.insert(TABLE_NAME, null, values);

    db.close();
  }

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