java Java数组记录
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Java array records
提问by Mr.Pengu
I need to get an variable type that has 3 types of values, the only way I know to do that is "Records", but I know there is no such type as "Records" in Java but ArrayList, but I don't get it...
我需要获得一个具有 3 种类型值的变量类型，我知道的唯一方法是“记录”，但我知道 Java 中没有“记录”这样的类型ArrayList，但是我不明白...
My result should be: (Don't know how it would look in Java, so I'm showing in different style)
我的结果应该是：（不知道它在 Java 中的样子，所以我以不同的风格展示）
TData = Record
Username : String;
UserID : Int ;
RowID : Int;
end;
users : array[1..10] of TData;
for(int i = 1; i < rowCount; i++){
TData.Username[i] = rs.GetString("Name");
TData.UserID[i] = rs.GetInt("UserID");
TData.RowID[i] = row;
}
Any suggestions on how to make something like this?
Is ArrayListthat I really need?
关于如何制作这样的东西的任何建议？ArrayList那真的是我需要的吗？
Thanks for the help, at the end i combined and got this result, works perfectly:
感谢您的帮助，最后我结合并得到了这个结果，完美运行：
class MyData {
private String userName;
private int userID;
private int RowID;
public MyData(String userName, int userID, int RowID) {
this.userName = userName;
this.userID = userID;
this.RowID = RowID;
}
public String getUserName() {
return userName;
}
public int getUserID() {
return userID;
}
public int getRowID() {
return RowID;
}
}
public void AList(){
ArrayList<MyData> users = new ArrayList<>();
try{
conn = DBConnection.DBConnector();
pst = conn.prepareStatement("SELECT * FROM TableUserData");
rs = pst.executeQuery();
row = 0;
while (rs.next()) {
users.add(new MyData(rs.getString("User_name"), rs.getInt("ID"), row));
row++;
}
for (MyData tmp : users) {
JOptionPane.showMessageDialog(null, "Users: " + tmp.getUserName() + " row: " + rtmp.getRowID());
}
}catch(Exception e){
JOptionPane.showMessageDialog(null, "Arraylist error: " + e);
}
}
回答by glglgl
You are mixing up things.
你把事情搞混了。
An ArrayListis a flexible alternative to an array and serves to store "a bunch" of data which have the same type.
AnArrayList是数组的灵活替代方案，用于存储“一堆”具有相同类型的数据。
The type of these data (of one entry) is up to you.
这些数据（一个条目）的类型由您决定。
The standard way of doing this in Java is to define a class like
在 Java 中这样做的标准方法是定义一个类
class MyData {
private String userName;
private int userID;
private int rowID;
public MyData(String userName, int userID, int rowID) {
this.userName = userName;
this.userID = userID;
this.rowID = rowID;
}
public String getUserName() {
return userName;
}
public int getUserID() {
return userID;
}
public int getRowID() {
return rowID;
}
}
and then
接着
ArrayList<MyData> users = new ArrayList<>();
while (rs.next()) {
users.add(new MyData(rs.GetString("Name"), rs.GetInt("UserID"), rs.GetInt("RowID")));
}
回答by Razib
Consider the following code snippet -
考虑以下代码片段 -
int salary;
float bonus;
char YesOrNo = 'Y';
Here salary, bonusand YesOrNoall of these are data and int, floatand charare data type. We called salaryis an inttype data, bonusis a floattype data. Here int, float, char- these data type are of primitive type in java.
在这里salary，bonus和YesOrNo所有这些都是数据int，float并char为数据类型。我们叫的salary是一种int类型的数据，bonus是一种float类型的数据。在这里int，float，char-这些数据类型是基本类型java。
In addition to primitive type you can create your own data type in object orientedprogramming language like - java. Here I think you can create a class of named Recordor with some other more meaningful name -
除了原始类型之外，您还可以object oriented使用诸如 - 之类的编程语言创建自己的数据类型java。在这里，我认为您可以创建一个命名类Record或使用其他更有意义的名称-
public class Record {
private String userName;
private int userId;
private int rowId;
public Record(String userName, int userId, int rowId){
this.userName = userName;
this.userId = userId;
this.rowId
}
//getter and setter methods if required
}
After that when you create a instance/object of Record-
之后，当您创建一个实例/对象时Record-
Record aRecord = new Record("user001", 1, 1);
Then in OOPwe called the newly created class - Recordas a user defined data type. Now we can called aRecordas a Recordtype data.
然后在OOP我们调用新创建的类——Record作为用户定义的数据类型。现在我们可以将其aRecord称为Record类型数据。
Then you can use ArrayListto store the Recordtype data -
然后你可以ArrayList用来存储Record类型数据 -
List<Record> recordList = new ArrayList<Recored>();
