如何在以下代码中获取 ResultSet 中的第一个元素：
public List getUserTest(String username, String password) {
List userList = new ArrayList();
Connection connection = null;
String rstring = null;
Statement stmt = null;///*******
ResultSet resultSet = null;
try {
connection = dataSource.getConnection();
stmt = connection.createStatement();///*******
resultSet = stmt.executeQuery("SELECT * FROM users WHERE (username)='" + username + "'"
+ "AND (password)='" + password + "'");///*******
while (resultSet.next()) {
UsersTest user = new UsersTest();
user.setId(resultSet.getString("id"));
user.setUsername(resultSet.getString("username"));
user.setPassword(resultSet.getString("password"));
userList.add(user);
}
} catch (SQLException e) {
System.err.println(e);
} finally { …