建立一個具有唯一ID列表，並操縱它

Question

我想創建一個用於創建，看起來像這樣

ID: 1 
Name: Example 
Surname: Example 
email: example 

//New list 

ID: 2 
Name: Example 
Surname: Example 
email: example 

，然後當我想改變的東西（如名稱：）列表的PROGRAMM我喜歡用ID來改變它，所以它只能在列表內改變與ID：2

Answer 1

你應該使用HashMap。包含ID，姓名，姓氏和電子郵件實例變量

創建一個類（讓我們一流的IT YourClass）。

然後創建一個HashMap其中關鍵的是標識和值YourClass：

Map<Integer,YourClass> map = new HashMap<>(); 
map.put(objectOfYourClassWithID1.getID(),objectOfYourClassWithID1); 
map.put(objectOfYourClassWithID2.getID(),objectOfYourClassWithID2); 
if (map.containsKey(2)) { 
    map.get(2).setSomeProperty(newValue); // this will only change the object whose ID is 2 
} 

Answer 2

你可以這樣

public class Record{ 
    private int id; 
    private String name; 
    private String Surname; 
    private String email; 

    public int getId() { 
     return id; 
    } 

    public void setId(int id) { 
     this.id = id; 
    } 

    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    public String getSurname() { 
     return Surname; 
    } 

    public void setSurname(String surname) { 
     Surname = surname; 
    } 

    public String getEmail() { 
     return email; 
    } 

    public void setEmail(String email) { 
     this.email = email; 
    } 
} 

創建類，然後使用它是這樣的：

Record record1 = new Record(); 
    record1.setId(1); 
    record1.setName("example"); 
    record1.setSurname("example"); 
    record1.setEmail("example"); 

    Record record2 = new Record(); 
    record2.setId(2); 
    record2.setName("example"); 
    record2.setSurname("example"); 
    record2.setEmail("example"); 

    Map<Integer,Record> recordMap = new HashMap<Integer, Record>(); 
    recordMap.put(record1.getId(),record1); 
    recordMap.put(record2.getId(),record2);] 

    recordMap.get(2).getName();//example 
    recordMap.get(2).setName("ebi"); 
    recordMap.get(2).getName();//ebi 

Answer 3

import java.util.ArrayList; 
import java.util.List; 

public class Person { 

private int id; 
private String name; 
private String Surname; 
private String email; 

public Person(int id, String name, String surname, String email) { 
    super(); 
    this.id = id; 
    this.name = name; 
    Surname = surname; 
    this.email = email; 
} 

public int getId() { 
    return id; 
} 

public void setId(int id) { 
    this.id = id; 
} 

public String getName() { 
    return name; 
} 

public void setName(String name) { 
    this.name = name; 
} 

public String getSurname() { 
    return Surname; 
} 

public void setSurname(String surname) { 
    Surname = surname; 
} 

public String getEmail() { 
    return email; 
} 

public void setEmail(String email) { 
    this.email = email; 
} 

public static void main(String[] args) { 

    List<Person> list = new ArrayList<Person>(); 
    list.add(new Person(1, "example", "example", "example")); 
    list.add(new Person(2, "example", "example", "example")); 
    } 

}