Question

I am trying to set the log in system on android using a username check between what the user inputs and what exists in the DB

Here is my piece of code, but it always gives me “invalid” and if i take the Try Catch block, it gives me a nullpointerException

public void checklogin(String logged){
    SQLiteDatabase db = null;
    DatabaseAdapter database = new DatabaseAdapter(this);       

        try{               
    Cursor mCursor = db.query(database.TABLE_USERS,new String[]{"select * from users"}, " Name like" + "'logged+'",null,null,null,null);

     if  (mCursor.moveToFirst()){
         Toast.makeText(LoginActivity.this, "Yaaaay", Toast.LENGTH_LONG).show();
     }}
        catch(NullPointerException e){
      Toast.makeText(LoginActivity.this, "invalid", Toast.LENGTH_LONG).show();

        }
        }

Answer 1

Well, you set db to be null… so when you call db.query it should rightfully give you a NullPointerException.