[英]Reading an arraylist Objects and their fields in another class(java)
我正在嘗試建立一個用戶登錄系統,我需要幫助閱讀另一個類中現有arraylist的objecs及其字段以進行身份驗證.Belowis是對象構造函數的代碼,
public class User {
public String UserName ;
public String UserSurname ;
public String UserUsername ;
public String UserPassword ;
public int UserType ; // 0 for cashier
// 1 for manager
public User() {}
public User(String UserName, String UserSurname, String UserUsername, String UserPassword, int UserType) {
this.UserName = UserName;
this.UserSurname = UserSurname;
this.UserUsername = UserUsername;
this.UserPassword = UserPassword;
this.UserType = UserType;
}
/*
Getters and Setters
*/
這是我的用戶和項目列表的“數據庫”( 注意 - 我有這些obj的構造函數)
public class DataBase {
ArrayList<User> userlist;
ArrayList<Item> itemlist;
public DataBase(){
User user1 = new User("example","example","example","example",1) ;
User user2 = new User("sda","fas","gdf","vcx",0) ;
User user3 = new User("htr","ytr","vxc","xaxxzx",0) ;
User user4 = new User("dag","gdf","dfgfgd","thrhf",0) ;
ArrayList<User> userlist = new ArrayList<User>();
userlist.add(user1);
userlist.add(user2);
userlist.add(user3);
userlist.add(user4);
ArrayList<Item> itemlist = new ArrayList<Item>() {};
Item item1 = new Item(1,"sadas",25.0) ;
Item item2 = new Item(1,"dcxz",25.0) ;
Item item3 = new Item(1,"czx",25.0) ;
Item item4 = new Item(1,"zxccxz",25.0) ;
Item item5 = new Item(1,"czx",25.0) ;
Item item6 = new Item(1,"tertgdf",25.0) ;
Item item7 = new Item(1,"zxcfes",25.0) ;
Item item8 = new Item(1,"erwt",25.0) ;
Item item9 = new Item(1,"gfdvcx",25.0) ;
Item item10 = new Item(1,"hjfgh",25.0) ;
itemlist.add(item1);
itemlist.add(item2);
itemlist.add(item3);
itemlist.add(item4);
itemlist.add(item5);
itemlist.add(item6);
itemlist.add(item7);
itemlist.add(item8);
itemlist.add(item9);
itemlist.add(item10);
}
public DataBase(ArrayList<User> userlist, ArrayList<Item> itemlist) {
this.userlist = userlist;
this.itemlist = itemlist;
}
public ArrayList<User> getUsers() {
return userlist;
} //end get Users
public ArrayList<Item> getItems(){
return itemlist;
} //end get Items
} // end class
這是我從上面顯示的ArrayList中讀取的內容..:
String username = UsernameField.getText();
String pass = PasswordField.getText();
try
{
users = new DataBase();
ArrayList<User> userlist = users.getUsers();
for(User d : userlist){
if(d.getUserUsername() != null && d.getUserUsername() == username && d.getUserPassword() != null && d.getUserPassword() == pass){
Succed success = new Succed();
success.setVisible(true);
}
else {
failure fail = new failure() ;
fail.setVisible(true);
}
}// end for
}/* end try */ catch (NullPointerException ex) {
}
如果有人可以幫我解決這個問題,我會很高興。我花了很多時間試圖解決這個問題。
動作偵聽器代碼:
LoginButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
LoginButtonActionPerformed(evt);
}
});
不應該使用==
來比較字符串的相等性,而是使用.equals()
。 ==
比較引用而不是字符串變量的內容。 為了比較內容,應根據要求使用.equals()
或.equalsIgnoreCase()
。
供參考,請參閱此內容
更新:
現在,您正在用戶列表上運行循環,並檢查輸入的用戶名是否在列表中。 而是這樣做:
Succed success = new Succed();
failure fail = new failure();
for(User d : userlist){
if(d.getUserUsername().equals(username) && d.getUserPassword().equals(pass)){
success.setVisible(true);
break;
}
}
if(!success.isVisible()){
fail.setVisible(true);
}
假設isVisible()
是在類中定義Succed
,其返回true
如果成功設置為可見,並返回false
的其它情況。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.