诚心求教，在TreeView中只new一次FORM如何实现
本帖最后由 u010466340 于 2013-07-06 16:43:34 编辑

  public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }
 private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            switch (e.Node.Name)
            {
                case "Node1":
                    Form1 F1 = new Form1();
                    F1.TopLevel = false;
                    F1.FormBorderStyle = FormBorderStyle.None;
                    F1.WindowState = FormWindowState.Maximized;
                    panel显示.Controls.Add(F1);
                    F1.Show();
                    break;

                case "Node2":
                    Form2 F2 = new Form2();
                    F2.TopLevel = false;
                    F2.FormBorderStyle = FormBorderStyle.None;
                    F2.WindowState = FormWindowState.Maximized;
                    panel显示.Controls.Add(F2); 
 
                    F2.Show();
                    break;

                case "Node3":
                    Form3 F3 = new Form3();
                    F3.TopLevel = false;
                    F3.FormBorderStyle = FormBorderStyle.None;
                    F3.WindowState = FormWindowState.Maximized;
                    panel显示.Controls.Add(F3);
                    F3.Show();
                    break;
            }
        }
    }

我现在想Form1，Form2，Form3 都只new一次，下次进入的时候就打开原来的form就好，请问如何实现？
[解决办法]
例如你可以写

 private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            switch (e.Node.Name)
            {
                case "Node1":
                    Form1.Show();
                    break; 
 

private Form1 F1;

public Form1 Form1
{
  get{
     if(F1==null)
     {
                    F1 = new Form1();
                    F1.TopLevel = false;
                    F1.FormBorderStyle = FormBorderStyle.None;
                    F1.WindowState = FormWindowState.Maximized;
                    panel显示.Controls.Add(F1);
     }
     return F1;
  }   
}

这样，不管调用多少次Form1属性，都回首先判断 if(F1==null)，仅仅初始化一次。