con = DriverManager.getConnection("jdbc:mysql://localhost:3306/oopdb","root","12345");
    st = con.createStatement();

    //set query
    String s = "SELECT Category FROM infocollected WHERE Adminno='123'";

    //save query result into rs
    rs = st.executeQuery(s);

    //retrieve category from result
    String category = rs.getString("Category");

    //print out result to console
    System.out.println("category");

while (rs.next()) {
String category = rs.getString("Category");
System.out.println(category);
}

// ...

//retrieve category from result
String category = rs.getString("Category");

//print out result to console
System.out.println(category);