Question

该项目打开一个对话框，让用户选择课程。它现在产生的输出只给我一个可供选择的课程。如何让课程班显示所有课程？

这是mainWindow文件：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace CreateClassesObjs
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        Course choice;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            Course course1 = new Course();
            Course course2 = new Course();
            Course course3 = new Course();
            Course course4 = new Course();
            Course course5 = new Course();
            Course course6 = new Course();
            Course course7 = new Course();

            course1.setName("IT 145");
            course2.setName("IT 200");
            course3.setName("IT 201");
            course4.setName("IT 270");
            course5.setName("IT 315");
            course6.setName("IT 328");
            course7.setName("IT 330");



            this.comboBox.Items.Add(course1);
            this.comboBox.Items.Add(course2);
            this.comboBox.Items.Add(course3);
            this.comboBox.Items.Add(course4);
            this.comboBox.Items.Add(course5);
            this.comboBox.Items.Add(course6);
            this.comboBox.Items.Add(course7);
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
            choice = (Course)(this.comboBox.SelectedItem);
            this.listBox.Items.Add(choice);
        }

    }
}

这是我的档案。

namespace CreateClassesObjs
{
    internal class Course

    {
        static string name;

        public Course()
        {

        }

        public string setName(string choice)
        {
            name = choice;

            return name.ToString();

        }

        /*
        public string retrieveName(string choice)
        {
            name = choice;
            return name.setName();
        }
        */

        public override string ToString()
        {


            return name;

        }

    }
}

这是我的输出：

它只打印最后一个值。什么时候应该打印所有这些;

course1.setName("IT 145");
course2.setName("IT 200");
course3.setName("IT 201");
course4.setName("IT 270");
course5.setName("IT 315");
course6.setName("IT 328");
course7.setName("IT 330");

ToString应该可以获得所有以前的字符串。

Answer 1

简短/快速回答（坚持代码背后）：

ComboBox仅支持选择单个项目。通过将其替换为ListBox，您可以将其配置为接受多个选定项。这些在SelectedItems属性中可用。

private void button_Click(object sender, RoutedEventArgs e)
{
    foreach(var choice in this.listBoxSource.SelectedItems.OfType<Course>())
    {
        this.listBox.Items.Add(choice);
    }
}

长答案（走MVVM方式）：

在Course类上实现INotifyPropertyChanged以支持正确的数据绑定。

将Selected属性添加到Course类。将DataTemplate添加到Source列表框，该列表框显示包含Selected Property的复选框的课程。

这将允许您使用数据绑定，因为您现在可以检查课程本身以查明它们是否被选中。这导致UI背后的代码更少，这使得更容易进行更改，维护和（单元）测试。

Answer 2

以下是我能够使该计划有效的方法。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace CreateClassesObjs
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        Course choice;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            Course course1 = new Course("IT 145");
            Course course2 = new Course("IT 200");
            Course course3 = new Course("IT 201");
            Course course4 = new Course("IT 270");
            Course course5 = new Course("IT 315");
            Course course6 = new Course("IT 328");
            Course course7 = new Course("IT 330");

            course1.setName("IT 145");
            course2.setName("IT 200");
            course3.setName("IT 201");
            course4.setName("IT 270");
            course5.setName("IT 315");
            course6.setName("IT 328");
            course7.setName("IT 330");

            this.comboBox.Items.Add(course1);
            this.comboBox.Items.Add(course2);
            this.comboBox.Items.Add(course3);
            this.comboBox.Items.Add(course4);
            this.comboBox.Items.Add(course5);
            this.comboBox.Items.Add(course6);
            this.comboBox.Items.Add(course7);
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
            choice = (Course)(this.comboBox.SelectedItem);
            this.listBox.Items.Add(choice);
        }

        class Course
        {
            private string name = "";


            public Course(string name)
            {
                this.name = name;
            }

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

            public string getName()
            {
                return name;
            }

            public override string ToString()
            {
                return getName();
            }
        }
    }
}

如何让WPF应用程序打印出多个值？

2 个答案: