为什么text2.Text =“message”在我的代码中不起作用？

Question

为什么text2.Text =“message”在我的代码中不起作用？ 我想在函数中以这种方式工作，参见代码。 我在Visual Stduio在C＃开发具有单声道的Android

的源代码：

using System; 
using Android.App; 
using Android.Content; 
using Android.Runtime; 
using Android.Views; 
using Android.Widget; 
using Android.OS; 

namespace ChatClient_Android 
{ 
[Activity(Label = "ChatClient_Android", MainLauncher = true, Icon = "@drawable/icon")] 
public class MainChat : Activity 
{ 
    protected override void OnCreate(Bundle bundle) 
    { 
     base.OnCreate(bundle); 

     // Set our view from the "main" layout resource 
     SetContentView(Resource.Layout.Main); 

     // Get our button from the layout resource, 
     // and attach an event to it 
     EditText text2 = FindViewById<EditText>(Resource.Id.text2); 
    } 

    private void recieved() 
    { 
    text2.Text = "mesage"; // The text2 does not existe in this context 

    } 
} 

}

Answer 1

EditText text2声明不是全局的，但该方法。把EditText text2;放在课堂上。

应该是这样的：

public class MainChat : Activity 
{ 
    EditText text2; // <----- HERE 
    protected override void OnCreate(Bundle bundle) 
    { 
     base.OnCreate(bundle); 
     SetContentView(Resource.Layout.Main); 
     text2 = FindViewById<EditText>(Resource.Id.text2); 
    } 

    private void recieved() 
    { 
    text2.Text = "mesage"; 

    } 
} 

Answer 2

text2是内部OnCreate定义，因此received对此一无所知。

您需要定义文本2为一类领域，如：

public class MainChat : Activity 
{ 
    private EditText text2; 
    protected override void OnCreate(Bundle bundle) 
    { 
     base.OnCreate(bundle); 

     // Set our view from the "main" layout resource 
     SetContentView(Resource.Layout.Main); 

     // Get our button from the layout resource, 
     // and attach an event to it 
     text2 = FindViewById<EditText>(Resource.Id.text2); 
    } 

    private void recieved() 
    { 
    text2.Text = "mesage"; // The text2 does not existe in this context 

    } 
}