练习：WinForm（控件Button，打开，关闭窗体）

Form1.cs

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            //在内存中创建form2对象
            Form2 f2 = new Form2();
            //展示当前窗体
            f2.Show();
        }

        /// <summary>
        /// 当加载窗体的时候，将窗体的对象放到Class1类中的静态字段中
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_Load(object sender, EventArgs e)
        {
            Class1._fTest = this;
        }
    }
}

Form2.cs

namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form3 f3 = new Form3();
            f3.Show();
        }
    }
}

Form3.cs

namespace WindowsFormsApplication1
{
    public partial class Form3 : Form
    {
        public Form3()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Class1._fTest.Close();
        }
    }
}

Class1.cs

namespace WindowsFormsApplication1
{
    class Class1
    {
        public static Form1 _fTest;
    }
}