Question

I am getting cursor index out of bounds “index 0 requested: with size 0”. Its just a user registration and login application. When there is no user with matching Username and Password my application is getting crashed.

Below is the code:

MainActivity.java

final SUSQLiteHelper dbhelper = new SUSQLiteHelper(this);

LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toString());

                if(login.getUname().toString().equals(loginuname.getText().toString()) && 
                        login.getPwd().toString().equals(loginpwd.getText().toString()))
                {
                    Toast.makeText(getApplicationContext(), "Login Successfull. Welcome " + login.getUname().toUpperCase() +" !".toString(), 
                            Toast.LENGTH_LONG).show();
                }
                else if(login.getUname().toString().equals(loginuname.getText().toString()) && 
                            !login.getPwd().toString().equals(loginpwd.getText().toString()))
                {                       
                    Toast.makeText(getApplicationContext(), "Login Failed. Incorrect password !", 
                            Toast.LENGTH_LONG).show();                      
                }
                else
                    Toast.makeText(getApplicationContext(), "Login Failed. User doesn't exist !", 
                            Toast.LENGTH_LONG).show(); //it never goes here if no username is found in the table

SUSQLiteHelper.java

    public LoginData readOneUser(String uname, String pwd)
{
    SQLiteDatabase loginUserDB = this.getReadableDatabase();
    LoginData newLogin = null;
    Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL, TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",
            new String[]{String.valueOf(uname)}, null, null, null);

    if(cursor.moveToFirst())
    {
        newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
    }
    cursor.close();
    loginUserDB.close();
    return newLogin;
}

LoginData.java

This class has getter and setter methods for Uname, Pwd, Email fields and a constructor which takes these fields as arguments.

Answer 1

CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0

It means that cursor.moveToFirst() returns false and Cursor is empty. So try to add the snippet for checking whether cursor is null or not and depends upon that modify your logic.

public LoginData readOneUser(String uname, String pwd)
{
 SQLiteDatabase loginUserDB = this.getReadableDatabase();
 LoginData newLogin = null;
 Cursor cursor = loginUserDB.query(TABLE_NAME, new String[]{TABLE_ROW_UNAME, TABLE_ROW_EMAIL,TABLE_ROW_PWD}, TABLE_ROW_UNAME + "=?",new String[]{String.valueOf(uname)}, null, null, null);

  if(cursor!=null) //Check whether cursor is null or not
  {
   if(cursor.moveToFirst())
   {
     newLogin = new LoginData(cursor.getString(0), cursor.getString(1), cursor.getString(2));
   }
  }
cursor.close();
loginUserDB.close();
return newLogin;
 }

---

  LoginData login = dbhelper.readOneUser(loginuname.getText().toString(), loginpwd.getText().toString());
  if(login!=null)
   {
     //check for incorrect username or password
    }
  else
   {
     //Notify that no Username available with these Username
   }