Я построил этот класс DBmanager для удобства, но метод getAllRows () вызывает суету вокруг исключений nullpointerexceptions. Я просто хочу использовать его, чтобы получить все строки без какой-либо фильтрации. Что я делаю не так?
package com.com.com;
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 DBManager {
private SQLiteDatabase db; // a reference to the database manager class.
private final String DB_NAME = "calls.db"; // the name of our database
private final int DB_VERSION = 1; // the version of the database
// the names for our database columns
private final String TABLE_NAME = "calls";
private final String TABLE_ROW_ID = "id";
public final String TABLE_ROW_ONE = "number";
public final String TABLE_ROW_TWO = "date";
public void addRow(String rowStringOne, String rowStringTwo){
// this is a key value pair holder used by android's SQLite functions
ContentValues values = new ContentValues();
// this is how you add a value to a ContentValues object
// we are passing in a key string and a value string each time
values.put(TABLE_ROW_ONE, rowStringOne);
values.put(TABLE_ROW_TWO, rowStringTwo);
// ask the database object to insert the new data
try
{
db.insert(TABLE_NAME, null, values);
}
catch(Exception e)
{
Log.e("DB ERROR", e.toString()); // prints the error message to the log
e.printStackTrace(); // prints the stack trace to the log
}
}
public Cursor getAllRows(){
Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null, null);
//Cursor cursor = db.query(TABLE_NAME, new String[] { TABLE_ROW_ID, TABLE_ROW_ONE, TABLE_ROW_TWO }, null, null, null, null, null);
return cursor;
}
/*
* SQLiteHelper Class
*/
private class CustomHelper extends SQLiteOpenHelper{
public CustomHelper(Context context){
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db){
// the SQLite query string that will create our 3 column database table.
String newTableQueryString =
"create table " +
TABLE_NAME +
" (" +
TABLE_ROW_ID + " integer primary key autoincrement not null," +
TABLE_ROW_ONE + " text," +
TABLE_ROW_TWO + " text" +
");";
// execute the query string to the database.
db.execSQL(newTableQueryString);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
// NOTHING TO DO HERE. THIS IS THE ORIGINAL DATABASE VERSION.
// OTHERWISE, YOU WOULD SPECIFIY HOW TO UPGRADE THE DATABASE
// FROM OLDER VERSIONS.
}
}
}