public class MainActivity extends AppCompatActivity {



ConnectionClass connectionClass;
EditText edtuserid,edtpass;
Button btnlogin;
ProgressBar pbbar;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    connectionClass = new ConnectionClass();
    edtuserid = (EditText) findViewById(R.id.edtuserid);
    edtpass = (EditText) findViewById(R.id.edtpass);
    btnlogin = (Button) findViewById(R.id.btnlogin);
    pbbar = (ProgressBar) findViewById(R.id.pbbar);
    pbbar.setVisibility(View.GONE);

    btnlogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DoLogin doLogin = new DoLogin();
            doLogin.execute("");

        }
    });

}

public class DoLogin extends AsyncTask<String,String,String>
{
    String z = "";
    Boolean isSuccess = false;


    String userid = edtuserid.getText().toString();
    String password = edtpass.getText().toString();


    @Override
    protected void onPreExecute() {
        pbbar.setVisibility(View.VISIBLE);
    }

    @Override
    protected void onPostExecute(String r) {
        pbbar.setVisibility(View.GONE);
        Toast.makeText(MainActivity.this,r,Toast.LENGTH_SHORT).show();

        if(isSuccess) {
            Intent i = new Intent(MainActivity.this, attendance.class);
            startActivity(i);
            finish();
        }

    }

    @Override
    protected String doInBackground(String... params) {
        if(userid.trim().equals("")|| password.trim().equals(""))
            z = "Please enter User Id and Password";
        else
        {
            try {
                Connection con = connectionClass.CONN();
                if (con == null) {
                    z = "Error in connection with The server";
                } else {
                    String query = "select * from tablename where id='" + userid + "' and Password='" + password + "'";
                    Statement stmt = con.createStatement();
                    ResultSet rs = stmt.executeQuery(query);

                    if(rs.next())
                    {

                        z = "Login successfull ";
                        isSuccess=true;
                    }
                    else
                    {
                        z = "Invalid Credentials";
                        isSuccess = false;
                    }

                }
            }
            catch (Exception ex)
            {
                isSuccess = false;
                z = "Exceptions";
            }
        }
        return z;
    }
}

public class ConnectionClass {
String ip = "192.168.....etc";
String classs = "net.sourceforge.jtds.jdbc.Driver";
String db = "dbname";
String un = "sql server login username";
String password = "*****";

@SuppressLint("NewApi")
public Connection CONN() {
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .permitAll().build();
    StrictMode.setThreadPolicy(policy);
    Connection conn = null;
    String ConnURL = null;
    try {

        Class.forName(classs);
        ConnURL = "jdbc:jtds:sqlserver://" + ip + ";"
                + "databaseName=" + db + ";user=" + un + ";password="
                + password + ";";
        conn = DriverManager.getConnection(ConnURL);
    } catch (SQLException se) {
        Log.e("ERRO", se.getMessage());
    } catch (ClassNotFoundException e) {
        Log.e("ERRO", e.getMessage());
    } catch (Exception e) {
        Log.e("ERRO", e.getMessage());
    }
    return conn;
}

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>