将数据库中的字符串与 Android Studio 中的字符串进行比较

Question

I am trying to compare a String in a Column in my SQLite Database to another String that i created while using cursor and Database Helper.

When i run the app despite what the database has, the app only goes to the UserMenu.class

Part of code: (the things commented out is me trying various things out. )

---

public void onClick(View v) {

    String email = Username.getText().toString();

    String pass = Password.getText().toString();


    String role = " ";

    String test2 = "Admin"; 

    cursor = db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_3+ " =? AND "+ DatabaseHelper.COL_2+ "=?",new String[]{email, pass});
    if (cursor!=null){
        if (cursor.getCount()> 0){

            db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_4+ " =?", new String[]{role});
            if(role.equals(test2)) {
                cursor.moveToNext();
                Toast.makeText(getApplicationContext(),"Success",Toast.LENGTH_SHORT).show();
                //cursor = db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_3+ " =?", new String[]{role2});
                // Toast.makeText(getApplicationContext(),"Cursor count: "+cursor.getCount(),Toast.LENGTH_SHORT).show();
                Intent i = new Intent(MainActivity.this, AdminMenu.class);
                startActivity(i);
            } else {
                cursor.moveToNext();
                //moveToUser();
                Toast.makeText(getApplicationContext(),"Success",Toast.LENGTH_SHORT).show();
                // = db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_3+ " =?", new String[]{role});
                //Toast.makeText(getApplicationContext(),"Cursor count: "+cursor.getCount(),Toast.LENGTH_SHORT).show();
                Intent i = new Intent(MainActivity.this, UserMenu.class);
                startActivity(i);
            }

        } else {
            Toast.makeText(getApplicationContext(),"Invalid email and/or password. Please try again.",Toast.LENGTH_SHORT).show();
        }
    }
}

Answer 1

You have defined:

String role = " ";
String test2 = "Admin";

and these variables are not changed anywhere in your code.
So the condition:

role.equals(test2)

returns false and the else block is executed.

Answer 2

The line db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_4+ " =?", new String[]{role});

is not much use as the result, the Cursor it returns, is not used.

The line if(role.equals(test2)) will always be false as role will be " " and test2 will be "Admin". So you always go to userMenu.

I guessing you want similar to

cursor = db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_3+ " =? AND "+ DatabaseHelper.COL_2+ "=?",new String[]{email, pass});
if (cursor.moveToFirst()){

    //db.rawQuery("SELECT * FROM "+ DatabaseHelper.TABLE_NAME + " WHERE "+ DatabaseHelper.COL_4+ " =?", new String[]{role});
    if (cursor.getString(cursor.getColumnIndex(DatabaseHelper.COL_4)).equals(test2)) {
        Toast.makeText(getApplicationContext(),"Success",Toast.LENGTH_SHORT).show();
        Intent i = new Intent(MainActivity.this, AdminMenu.class);
        cursor.close();
        startActivity(i);
    }
    else{
        Toast.makeText(getApplicationContext(),"Success",Toast.LENGTH_SHORT).show();
        Intent i = new Intent(MainActivity.this, UserMenu.class);
        cursor.close();
        startActivity(i);
    }

} else {
    Toast.makeText(getApplicationContext(),"Invalid email and/or password. Please try again.",Toast.LENGTH_SHORT).show();
    cursor.close();
}

No good checking if Cursor is null it not be null from query. query fail or get good Cursor. Cursor if no rows Cursor not move.

Using moveToFirst replaces getCount as moveToFirst will be false if count 0 if not it move the Cursor position to first row and values can be got from the Cursor. So does two things.

Not know if row found has proper value for role but other query with comments now will get all row with role not just from email row so any ADMIN and always AdminMenu. So first query only needed I think.