我的代码抛出这个异常：线程“AWT-EventQueue-0”中出现异常。
当我输入mongodb在数据库中找不到的用户名或密码时，它会抛出异常。我尝试了很多方法来调试它，但我找不到抛出异常的语句。
问题是，当用户名或密码在数据库中不匹配时，我希望向用户显示一条消息

public class GetEmployee {

MongoClient mongoClient = MongoClients.create();
MongoDatabase db = mongoClient.getDatabase("MirandasShoes");
MongoCollection<Document> collection = db.getCollection("Employees");

public Employee getEmployee(String username, String password) {
    FindIterable<Document> findIterable = collection.find(new Document("Username", username).append("Password", password));
    MongoCursor<Document> cursor = findIterable.iterator();
    Employee e = new Employee();
    if (cursor.hasNext()) {
        Document doc = cursor.next();
        //ArrayList<Object> o = new ArrayList<>(doc.values());
        e.setId(doc.get("_id").toString());
        e.setName(doc.get("Name").toString());
        e.setAddress(doc.get("Address").toString());
        e.setEmail(doc.get("Email").toString());
        e.setPhone(doc.get("Phone").toString());
        e.setUsername(doc.get("Username").toString());
        e.setPassword(doc.get("Password").toString());
    }
    return e;//Get the shoes
}

}