TabPage不断创建。 C＃

Question

TabPage keeps being created even the tab page already exists in my tab control. Please consider my code below:

void button1_Click(object sender, EventArgs e)
{
    TabPage tabPage = new TabPage();
    tabPage.Name = "TestNewTab";
    tabPage.Text = "Tab Page";

    // Check if the tabpage is not yet existing
    if (!tabControl1.TabPages.Contains(tabPage))
    {
        // Add the new tab page
        tabControl1.TabPages.Add(tabPage);
    }
}

What's wrong with my code? Thanks.

Answer 1

My guess would be that TabPages.Contains is checking for an object reference, since you're instantiating a new TabPage every time, it won't be the same object. Try looping through the tab pages and comparing the Name property instead.

Answer 2

The problem is that .Contains will check for an equal reference, which is not the same as an equal value, when looking for a reference type like TabPage . A simple way to fix your problem might be to do something like this:

TabPage tabPage;

void button1_Click(object sender, EventArgs e)
{
    // Check if the tabpage doesn't exist yet:
    if (tabPage == null)
    {
        // Create the tab page:
        tabPage = new TabPage();
        tabPage.Name = "TestNewTab";
        tabPage.Text = "Tab Page";

        // Add the new tab page:
        tabControl1.TabPages.Add(tabPage);
    }
}