通过从类到主窗体的调用更新控件和刷新表单

Question

我想在其他课程中做一些事情时更新文本框。让我把我的代码：

Form1.cs的

namespace TestApp
{
    public partial class Form1 : Form
    {
        CalledClass call = new CalledClass();

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            call.Call_UpdateBox();
        }

        public void UpdateBox()
        {
            textBox1.Text = "hello";
        }
    }
}

CalledClass.cs

namespace TestApp
{
    class CalledClass
    {
     public void Call_UpdateBox()
        {
            Form1 mainform = new Form1();

            //do looping for doing some tasks here and update textbox every time
            mainform.UpdateBox();
        }
    }
}

当单击主窗体上的按钮时，将调用CalledClass中的Call_UpdateBox函数，我必须在其中执行一些循环，并在更新主窗体中的文本框之间。虽然如果我在调试模式下看到它的值，文本框会更新，但它在主窗体上保留空白。请建议。 Thx提前。

Answer 1

您正在声明Form1的新实例，而不是引用已存在的实例。你应该：

namespace TestApp
{
    public partial class Form1 : Form
    {
        CalledClass call = new CalledClass();

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            call.Call_UpdateBox(this);
        }

        public void UpdateBox()
        {
            textBox1.Text = "hello";
        }
    }
}
namespace TestApp
{
    class CalledClass
    {
     public void Call_UpdateBox(Form1 Sender)
        {
            //do looping for doing some tasks here and update textbox every time
            sender.UpdateBox();
        }
    }
}

Answer 2

您正在创建一个新的表单实例，甚至不显示它。所以你不是在好的对象实例上调用UpdateBox()。

相反，请重新使用您mainForm的当前实例。例如：

public void Call_UpdateBox(Form1 targetForm)
{
    targetForm.UpdateBox();
}

private void button1_Click(object sender, EventArgs e)
{
    call.Call_UpdateBox(this);
}

Answer 3

您可以使用Threads但更简单的方法，因为您在WindowsForms中使用的是BackgroundWorker，

你的Form1会像：

public partial class Form1 : Form
{
    BackgroundWorker _bw = new BackgroundWorker();
    CalledClass call = new CalledClass();

    public Form1()
    {
        InitializeComponent();

        bw.DoWork += bw_DoWork;
        bw_ProgressChanged += bw_ProgressChanged;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (bw.IsBusy != true)
        {
            bw.RunWorkerAsync();
        }
    }

    private void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        call.Call_UpdateBox();
    }

    private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        textBox1.Text = "hello";

        // Here you can access some progress property from CalledClass in order to monitor and inform progress
    }
}

Answer 4

最简单的方式

namespace TestApp
{
    public partial class Form1 : Form
    {
        CalledClass call = new CalledClass();

        public Form1()
        {
            InitializeComponent();
            call.FormH = this;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            call.Call_UpdateBox();
        }

        public void UpdateBox()
        {
            textBox1.Text = "hello";
        }
    }
}

namespace TestApp
{
    class CalledClass
    {
        public static Form1 FormH;

        public void Call_UpdateBox()
        {
            //do looping for doing some tasks here and update textbox every time
            FormH.UpdateBox();
        }
    }
}