[英]Getting variable value from another class
因此,我有一个名为Members
的类,还有另一个名为DBConnect
类,该类将连接到数据库,然后将数据库中的值存储到Members
类。 然后,我想在另一个名为Controller
类中使用来自Members
类的值。 但是,我在Controller
类中创建了Object的新实例,如果从那里使用get()
方法,它将导致返回null
。
但是,如果我在DBConnect
类中执行所有操作,则可以。 它将返回名字而不是null
Members
等级
package Database;
public class Members {
private String firstName;
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
DBConnect
类
package Database;
import java.sql.*;
public class DBConnect {
private Connection connection;
private Statement statement;
private ResultSet resultSet;
Members members = new Members();
public DBConnect() {
try {
Class.forName("com.mysql.cj.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/finance", "root", "");
statement = connection.createStatement();
System.out.println("Successfully connected to DATABASE.");
} catch (Exception ex) {
System.out.println("ERROR: Can't connect to the Database! -> " + ex);
}
}
public void getData(int id) {
try {
String query = "select * from Members where MembersId = '" + id + "'";
resultSet = statement.executeQuery(query);
while (resultSet.next()) {
members.setId(resultSet.getInt("MembersId"));
members.setFirstName(resultSet.getString("MembersFirstName"));
members.setLastName(resultSet.getString("MembersLastName"));
members.setPosition(resultSet.getString("MembersPosition"));
members.setHourlyRate(resultSet.getDouble("MembersHourlyRate"));
members.setGraduated(resultSet.getString("MembersGraduated"));
members.setLanguages(resultSet.getString("MembersLanguages"));
members.setCountry(resultSet.getString("MembersCountry"));
members.setCity(resultSet.getString("MembersCity"));
members.setAddress(resultSet.getString("MembersAddress"));
}
}catch (Exception ex) {
System.out.println("Error: " + ex);
}
}
}
Controller
类
package sample;
import Database.DBConnect;
import Database.Members;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.scene.effect.DropShadow;
import javafx.scene.image.Image;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.paint.ImagePattern;
import javafx.scene.shape.Circle;
import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.ResourceBundle;
public class Controller implements Initializable {
private DBConnect dbConnect;
private Members members;
@FXML
private HBox sidebarMembers;
@FXML
private void openSidebarMembers(MouseEvent event) throws IOException {
dbConnect = new DBConnect();
dbConnect.getData(2);
members = new Members();
if (event.getSource() == sidebarMembers) {
System.out.println(members.getFirstName());
}
}
据我了解,当您创建一个新对象时,它将导致将所有变量初始化为0。除了使它们成为静态对象之外,我还应该如何访问这些值?
所以我的问题是,我怎么能访问我设置为我的价值观Members
类从DBConnect
类在我的Controller
类?
在DbConnect类中,将getData方法的返回类型更改为Member。
public Member getData(int id)
现在,您可以从控制器访问该成员
Member member = dbConnect.getData(2);
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.