MDI 未显示表单/窗口的最新变体

Question

我现在正在制作一个链接到多个不同表单（“添加项目”、“关于”等）的 MDI。我不认为上下文太重要，因为我的问题是当我编辑不同的子表单时，当我运行程序时新版本不会显示。我包含了父表单 (frmParent) 和添加项目表单 (frmAdd) 中的完整代码

namespace MDIDemo
{
    public partial class frmParent : Form
    {
        public static LibraryClass l1 = new LibraryClass();

        public frmParent()
        {
            InitializeComponent();
        }

        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
        {
            // Allocate memory for our about box
            frmAboutBox frmAbt = new frmAboutBox();

            // Assign the parent:
            frmAbt.MdiParent = this;        // This is the parent/main form

            frmAbt.Show();
        }

        private void closeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (ActiveMdiChild != null)
            {
                ActiveMdiChild.Close();
            }
        }

        private void closeAllToolStripMenuItem_Click(object sender, EventArgs e)
        {
            while (ActiveMdiChild != null)
            {
                ActiveMdiChild.Close();
            }
        }

        private void menuStrip1_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
        }

        private void cascadeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.Cascade);
        }

        private void tileHorizontalToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileHorizontal);
        }

        private void tileVerticalToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.TileVertical);
        }

        private void arrangeIconsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.LayoutMdi(MdiLayout.ArrangeIcons);
        }

        private void addToolStripMenuItem_Click(object sender, EventArgs e)
        {
            // Allocate memory for our add box
            frmAdd add1 = new frmAdd();

            // Assign the parent:
            add1.MdiParent = this;    // This is the parent/main form

            add1.Show();
        }

        private void showItemsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmShow show1 = new frmShow();
            
            show1.MdiParent = this;

            show1.Show();
        }
    }
}

namespace MDIDemo
{
    public partial class frmAdd : Form
    {
        public frmAdd()
        {
            InitializeComponent();
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btnClr_Click(object sender, EventArgs e)
        {
            txtISBN.Clear();
            txtAuth.Clear();
            numNum.Value = 0; 
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            ItemRec item1;
            
            item1.iSBN = "ISBN";
            item1.AuthorName = "Last First";
            item1.numOwned = 0;
            item1.numOnLoan = 0;

            try
            {
                item1.iSBN = txtISBN.Text;
                item1.AuthorName = txtAuth.Text;
                item1.numOwned = Convert.ToInt32(numNum.Value);
            }
            catch (Exception ex)
            {
                MessageBox.Show(txtISBN.Text + " is not an integer.",
                                                "Data entry error",
                                                MessageBoxButtons.OK,
                                                MessageBoxIcon.Error);
            }



            // Add the item to our list: 

            try
            {
                frmParent.l1.Insert(item1);
            }
            catch (ListIsFullException ex)
            {
                MessageBox.Show(ex.Message,
                               "Data entry error",
                               MessageBoxButtons.OK,
                               MessageBoxIcon.Error);
            }

        }

        private void frmAdd_Load(object sender, EventArgs e)
        {

        }
    }
}

我不知道要尝试什么，我尝试简单地删除并重新输入声明之类的东西，但（毫不奇怪）这似乎没有做任何事情。

Answer 1

好的，我修好了。首先，我尝试删除 bin 文件夹，然后重建解决方案，但这不起作用，所以我后退一步，我认为我删除了项目文件夹，然后尝试重建，但它不起作用，所以我取消了删除并运行它，我相信之后它就起作用了。我很困惑，但至少它正在运行。如果有人知道为什么会发生这种情况并想分享，请随意。