The progress you are currently learning does not use the database.
I'd like to create a membership form by creating a form with a thin builder.It's a little hard to do without using the database.
I heard that you can use List or Map... It's a little difficult to use these two.
I'm trying to use what I learned, but it's not easy.
HashMap list = new ArrayList<>(); What does it mean?
HashMap list = new HashMap()>(); What is this about? Is it possible to implement?
First of all, what I thought. If the key value of HashMap and any keyid in the value are the same, I want to delete and modify this ID... The value in the value is ID, password, name, gender, address...and so on.
Is there no need to make a keyid and check it? If the key value is correct, can I modify, delete, or log in?
Maybe it's because my head is complicated, but I feel like I'm mixed up. Please help me
java
First of all, number 1 is wrong grammar in your question.
Use it like #2 or Map map = new HashMap();. Map is an interface, and HashMap is an implementation. They use it because of polymorphism.
If you use a data structure instead of a database, it would be better to use a map rather than a list.
For example, we can implement the following through the User class and Database class. I hope it was a good hint!
public class User {
private String id;
private String password;
public getId(){
return this.id;
}
//construct, get, tostring
}
public class Database {
private static Map<String, User> users = new HashMap<String, User>();
public static void addUser(User user) {
users.put(user.getId(), user);
}
public static void removeUser(){};
public static void updateUser(){};
....
}
If you really want to do well, please learn "data structure/algebra" in advance.
You can solve it without any problems by sorting and searching by listing (linked, etc.), stacking, queue (de), tree, graph, and sorting and searching.
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