JavaのListメソッドで宣言されているArrayListを参照するには？

Question

モデル：

@Entity(name= "User") 
@Table(name= "Registration") 
public class User { 

private int id; 
private String orderNo; 
private String productName; 
private BigDecimal price; 
private Integer qty; 
private Boolean editable; 

public User(){ 
} 

public User(int id, String orderNo, String productName, BigDecimal price, Integer qty){ 
    this.id= id; 
    this.orderNo= orderNo; 
    this.productName= productName; 
    this.price= price; 
    this.qty= qty; 
} 

public int getId() { 
    return id; 
} 
public void setId(int id) { 
    this.id = id; 
} 
public String getOrderNo() { 
    return orderNo; 
} 
public void setOrderNo(String orderNo) { 
    this.orderNo = orderNo; 
} 
public String getProductName() { 
    return productName; 
} 
public void setProductName(String productName) { 
    this.productName = productName; 
} 
public BigDecimal getPrice() { 
    return price; 
} 
public void setPrice(BigDecimal price) { 
    this.price = price; 
} 
public Integer getQty() { 
    return qty; 
} 
public void setQty(Integer qty) { 
    this.qty = qty; 
} 
    public Boolean getEditable() { 
    return editable; 
} 

    public void setEditable(Boolean editable) { 
     this.editable = editable; 
    } 
} 

ダオはmetod：

public class UserDao implements UserInterface{ 

    private static final Logger logger= LoggerFactory.getLogger(UserDao.class); 

       Session session= HibernateUtil.getSessionFactory().openSession(); 

       public void save(User newUser){ 
       // Session session= HibernateUtil.getSessionFactory().openSession(); 
        session.beginTransaction(); 
        session.save(newUser); 
        session.getTransaction().commit(); 
        session.close(); 
       } 


       @SuppressWarnings("unchecked") 
       public Integer getId() { 
        String hql = "SELECT MAX (user.id) FROM User user"; 
        Query<Integer> query = session.createQuery(hql); 
        List<Integer> results = query.list(); 
        Integer userId = 1; 

        if(results.get(0)!= null) { 
         userId= results.get(0)+ 1; 
        } 

        return userId; 
       } 

      @SuppressWarnings("unchecked") 
      @Override 
      public List<User> listUsers() { 
       // TODO Auto-generated method stub 
       Session session= HibernateUtil.getSessionFactory().openSession(); 
       List<User> userList= session.createQuery("FROM User").list(); 
       for(User u: userList){ 
        logger.info("Users list:: "+ u); 
       } 
       return userList; 
      } 
} 

マネージドBean：

@ManagedBean(name= "myBean", eager= true) 
@RequestScoped 
public class UserDrivingBean { 

    private String orderNo; 
    private String productName; 
    private BigDecimal price; 
    private Integer qty; 

    List<User> users; 

    public List<User> getUsers() { 
     return users; 
    } 

    public void setUsers(List<User> users) { 
     this.users = users; 
    } 

    public String saveUser(){ 
     UserDao userDao= new UserDao(); 
     Integer userId= userDao.getId(); 
     User user= new User(userId, orderNo, productName, price, qty); 
     userDao.save(user); 
     System.out.println("User successfully saved!"); 
     return "output"; 
    } 

    public void addUser(){ 
     UserDao userDao= new UserDao(); 
     Integer userId= userDao.getId(); 
     User newUser= new User(userId, orderNo, productName, price, qty); 
     newUser.setEditable(true); 
     userDao.addCustomer(newUser); 
    } 

    public void plusNewUser(){ 
     UserDao daoObj= new UserDao(); 
     List<User> users= getAllUsers(); 
     Integer userId= daoObj.getId(); 
     User addUser= new User(); 
     addUser.setEditable(true); 
     users.add(addUser); 
    } 

    public List<User> getAllUsers(){ 
     users= new ArrayList<>(); 
     UserDao daoObj= new UserDao(); 
     users= daoObj.listUsers(); 
    /* Integer userId= daoObj.getId(); 
     User addUser= new User(userId, orderNo, productName, price, qty); 
     addUser.setEditable(true); 
     users.add(addUser); */ //!!!This works, when added directly to method! 
     return users; 
    } 

    public String getOrderNo() { 
     return orderNo; 
    } 
    public void setOrderNo(String orderNo) { 
     this.orderNo = orderNo; 
    } 
    public String getProductName() { 
     return productName; 
    } 
    public void setProductName(String productName) { 
     this.productName = productName; 
    } 
    public BigDecimal getPrice() { 
     return price; 
    } 
    public void setPrice(BigDecimal price) { 
     this.price = price; 
    } 
    public Integer getQty() { 
     return qty; 
    } 
    public void setQty(Integer qty) { 
     this.qty = qty; 
    } 

XHTMLページ：

<?xml version="1.0" encoding="UTF-8" ?> 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml" 
     xmlns:h="http://xmlns.jcp.org/jsf/html"  
     xmlns:f="http://xmlns.jcp.org/jsf/core"> 
<h:head> 
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
<title>Retreiving func.</title> 
</h:head> 
<h:body> 
<f:view> 
<h:form id="adminInf"> 
<center> 
    <h:dataTable border="1" id="table" var="y" value="#{myBean.allUsers}"> 
    <h:column> 
    <f:facet name="header"> 
    <h:outputLabel value="Id: "/> 
    </f:facet> 
    <h:outputText value="#{y.id}"/> 
    </h:column> 
    <h:column> 
    <f:facet name="header"> 
    <h:outputLabel value="Order No: "/> 
    </f:facet> 
    <h:inputText value="#{y.orderNo}" rendered="#{y.editable}"></h:inputText> 
    <h:outputText value="#{y.orderNo}" rendered="#{!y.editable}"/> 
    </h:column> 
    <h:column> 
    <f:facet name="header"> 
    <h:outputLabel value="Product: "/> 
    </f:facet> 
    <h:inputText value="#{y.productName}" rendered="#{y.editable}"></h:inputText> 
    <h:outputText value="#{y.productName}" rendered="#{!y.editable}"/> 
    </h:column> 
    <h:column> 
    <f:facet name="header"> 
    <h:outputLabel value="Price: "/> 
    </f:facet> 
    <h:inputText value="#{y.price}" rendered="#{y.editable}"></h:inputText> 
    <h:outputText value="#{y.price}" rendered="#{!y.editable}"/> 
    </h:column> 
    <h:column> 
    <f:facet name="header"> 
    <h:outputLabel value="Quantity: "/> 
    </f:facet> 
    <h:inputText value="#{y.qty}" rendered="#{y.editable}"></h:inputText> 
    <h:outputLabel value="#{y.qty}" rendered="#{!y.editable}"/> 
    </h:column> 

    <h:column id="insertBtn"> 
    <h:commandButton value="Insert" action="#{myBean.addUser}" rendered="#{y.editable}"> 
    <f:ajax execute="@form" render="@form"/> 
    </h:commandButton> 
    </h:column> 
    </h:dataTable> 
    <h:commandButton value="AddNew" action="#{myBean.plusNewUser}" update="table"/> 
    <h:commandLink value="Home" action="input"/> 
</center> 
</h:form> 
</f:view> 
</h:body> 
</html> 

はそれがを参照することが可能ですpublic List getAllUsers（）{}メソッドで新しいオブジェクトを追加できるように宣言した別のメソッドの？例えば ：この方法で

public void addNewUser(){ 
     User addUser= new User(userId, orderNo, productName, price, qty);//Create new object 
     addUser.setEditable(true);// Open new iput fields(<h:inputText>)on xhtml page 
     users.add(addUser);//refer to ArrayList from getAllUsers() method and add new object in it(new User). 
} 

私は、XHTMLページにDBからデータを盗ん：

public List<User> getAllUsers(){ 
    List<User> users= new ArrayList<>(); 
    UserDao daoObj= new UserDao(); 
    users= daoObj.listUsers(); 
    return users; 
} 

Answer 1

はい、それはJavaのジェネリックの概念で可能です。

List<User> users= new ArrayList<User>(); 



public class SomeClass { 


List<User> users= new ArrayList<User>(); 
    public List<User> getAllUsers(){ 
     // here just use the global variable, no need to add List<User> again 
     users = new ArrayList<>(); 
     UserDao daoObj = new UserDao(); 
     users = daoObj.listUsers(); 
     return users; 
    } 

    public void addNewUser() { 
     users = getAllUsers(); 
     User addUser = new User(userId, orderNo, productName, price, qty);//Create new object 
     addUser.setEditable(true);// Open new input fields(<h:inputText>)on xhtml page 
     users.add(addUser);//refer to ArrayList from getAllUsers() method and add new object in it(new User). 

     // save user to DOA, depend on how you create your DAO, it maybe something like 
     UserDao daoObj = new UserDao(); 
     daoObj.insertUser(addUser); 
    } 
} 

Answer 2

は、私が何をやりたいことはpublic void addNewUser()のように別の方法からpublic List<User> getAllUsers()方法に存在しているList<User> users = new ArrayList<>();を得ることであると信じています。上記質問する

答えはありませんあなたが、ない限りは、あなたのコード内で何かを変更することはできませんです。

EDIT

ローカル宣言を維持したい場合は、このようにそれを作成することができます。

public class SomeClass { 

    public List<User> getAllUsers(){ 
     // here just use the global variable, no need to add List<User> again 
     List<User> users = new ArrayList<>(); 
     UserDao daoObj = new UserDao(); 
     users = daoObj.listUsers(); 
     return users; 
    } 

    public void addNewUser() { 
     List<User> users = getAllUsers(); 
     User addUser = new User(userId, orderNo, productName, price, qty);//Create new object 
     addUser.setEditable(true);// Open new input fields(<h:inputText>)on xhtml page 
     users.add(addUser);//refer to ArrayList from getAllUsers() method and add new object in it(new User). 

     // save user to DOA, depend on how you create your DAO, it maybe something like 
     UserDao daoObj = new UserDao(); 
     daoObj.insertUser(addUser); 
    } 
} 

あなたは新しいユーザーを追加した後でDAOにユーザーを保存しましたか？