NullPointerException on getReadableDatabase()

Question

I have this method in a class (non-activity) -

public boolean usernameChk(String usrname) {

    String usrnmQuery = \"SELECT * FROM \" + TABLE_ACCOUNTS + \"         


        

Answer 1

You have not passed proper context of your activity that is why its throwing nullpointer error.

Just change your method as below.

public boolean usernameChk(String usrname){

    String usrnmQuery = "SELECT  * FROM " + TABLE_ACCOUNTS  + " WHERE username = '" + usrname + "'";
    SQLiteDatabase db = this.getReadableDatabase();

Declare one common Context in your DatabaseHelper and assign the value of constructor in your while creating instance of your helper class as below:

public Context m_context;
public DatabaseHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    m_context = context;
}