Myujth

I'm trying to access a row in my database from MainActivity in the following fashion. I'd like to know a better way to do this since this crashes my app with the error every time. Even after cold rebooting and wiping data.

"23:06 Emulator: glTexImage2D: got err pre :( 0x502 internal 0x1908 format 0x1908 type 0x1401

I assume there is a better way to do this. I'm calling a method which takes a User object which is stored in my database presumably at index 1. (first place in database)

 if(myDb.isNotEmpty() == true) {
 MyProgress.calculateBalance***(myDb.getUser(1));***

this is my getUser method.

public User getUser(int id) 
 SQLiteDatabase db = this.getReadableDatabase();
 Cursor cursor = db.query(TABLE_NAME, // a. table
 COLUMNS, // b. column names
 " id = ?", // c. selections
 new String String.valueOf(id) , // d. selections args
 null, // e. group by
 null, // f. having
 null, // g. order by
 null); // h. limit

 if (cursor != null)
 cursor.moveToFirst();

 User user = new User();
 user.setId(Integer.parseInt(cursor.getString(0)));
 user.setWeight (Integer.parseInt(cursor.getString(1)));
 user.setAge(Integer.parseInt(cursor.getString(2)));

 return user;
 

The last part of your method should look like this:

if ((cursor != null) && (cursor.moveToFirst()) 
 User user = new User(); 
 user.setId(Integer.parseInt(cursor.getString(0)));
 user.setWeight (Integer.parseInt(cursor.getString(1)));
 user.setAge(Integer.parseInt(cursor.getString(2)));
 return user;
 else 
 return null;

This code ensures that the if the cursor returned is null or does not contain at least 1 row, it will not throw an error.

In this case the method will return null.

Of course if the cursor is prepared with no errors and myDB is properly initialized there is no reason for the cursor to be null, so you must check for valid column, table and database names.

Also after every change you make to any of these always uninstall the app from the emulator/device so the database is deleted and rerun the app to recreate everything.

Better way would be use Save data in a local database using Room

Here is your code I see null check is done but it protect only one statement from NPE. You need to wrap user creation under this if condition.

@Nullable
public User getUser(int id) 
 SQLiteDatabase db = this.getReadableDatabase();
 Cursor cursor = db.query(TABLE_NAME, // a. table
 COLUMNS, // b. column names
 " id = ?", // c. selections
 new String String.valueOf(id) , // d. selections args
 null, // e. group by
 null, // f. having
 null, // g. order by
 null); // h. limit

 if (cursor != null && cursor.moveToFirst()) 
 User user = new User();
 user.setId(Integer.parseInt(cursor.getString(0)));
 user.setWeight (Integer.parseInt(cursor.getString(1)));
 user.setAge(Integer.parseInt(cursor.getString(2)));

 return user;
 

 return null;