String query = "select name from table1";
    try {
        con = connectionClass.CONN();
        stmt = con.createStatement();
        rs = stmt.executeQuery(query);
        .....

java.lang.NullPointerException:Attempt to invoke virtual method 'java.sql.Connection com.example.ashfaqafzal.emapp.ConnectionClass.CONN()' on a null object reference

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;
}