public class LoginActivity extends ActionBarActivity {
Button loginButton;

String txtUsername;
String txtPassword;
EditText password;
EditText username;

@Override
protected void onCreate(Bundle saveInstanceState) {
    super.onCreate(saveInstanceState);
    setContentView(R.layout.activity_login);

    loginButton = (Button) findViewById(R.id.login);

    loginButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            txtUsername = username.getText().toString();
            txtPassword = password.getText().toString();

            ParseUser.logInInBackground(txtUsername, txtPassword, new LogInCallback() {
                @Override
                public void done(ParseUser user, ParseException e) {
                    if (user != null) {
                        Intent intent = new Intent(LoginActivity.this, Welcome.class);
                        startActivity(intent);
                        finish();
                    } else {
                        Toast.makeText(getApplicationContext(), "This user does not exist! Please Sign up", Toast.LENGTH_SHORT).show();
                    }
                }
            });
        }
    });
}

public class ParseConnector extends MultiDexApplication {

    @Override
    public void onCreate(){
    super.onCreate();

    Parse.initialize(this, "ZzfoJHON4Gc******2YlIhOFT3Tk8GOoANeO", "9ikHKNBO6BfmNRMauxckoB******ZzxlBPYDL");
    ParseInstallation.getCurrentInstallation().saveInBackground();
        ParseUser.enableAutomaticUser();
        ParseACL defaultACL = new ParseACL();
        defaultACL.setPublicReadAccess(true);
        ParseACL.setDefaultACL(defaultACL, true);
}