'MyFirstApp.Resource.Id' does not contain a definition for 'myButton' (CS0117) (MyFirstApp)

Question

Main Activity I'm naming my project "MyFirstApp"

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

namespace MyFirstApp
{
    [Activity (Label = "MyFirstApp", MainLauncher = true)]
    public class MainActivity : Activity
    {
        int count = 1;

        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
            Button button = FindViewById<Button> (Resource.Id.myButton);

            button.Click += delegate {
                button.Text = string.Format ("{0} clicks!", count++);
            };
        }
    }
}

Layout res/layout

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
    <EditText
        android:id="@+id/edit_message"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:hint="Enter Message" />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send"
        android:id="@+id/button_send" />
</LinearLayout>

Strings

    <?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">My First App</string>
    <string name="edit_message">Enter a message</string>
    <string name="button_send">Send</string>
    <string name="action_settings">Settings</string>
    <string name="title_activity_main">MainActivity</string>
</resources>

Please help me i'm beginner in android development if there is anything not clear i'll try to add more details i'm using Xamarin for developing

Thanks

Solution 1

add the attribute:

android:id="@+id/myButton"

to your button in the layout xml file.

Then in your Activity you can find your button like this:

Button button = (Button) findViewById(R.id.myButton);

Instead of:

Button button = FindViewById<Button> (Resource.Id.myButton);

Update: Well, the findViewById I propsed was plain Android, not sure how it works in Xamarin, but for sure your button needs an id in the xml

Update 2: Actually you already had and Id for your button, but it is not myButton, it is button_send ==> so you may want to use that one instead myButton

Solution 2

in your layout, the button id is - button_send:

android:id="@+id/button_send"

So in the activity code, when you "finding" this button, you should use that id, so instead

Button button = FindViewById<Button> (Resource.Id.myButton);

You should use

Button button = FindViewById<Button> (Resource.Id.button_send);

Solution 3

The problem is that some internal scaffolding piece is generating bogus code assuming the identity of the button added to the layout. There is no context by which to determine which of the two buttons added for the walk through is supported by 'MyButton'. I just renamed it the "Translate Button" because I added that button first. Not sure what I'll do when I start with real apps.

Back in the old days, we would give this type of stuff to an in-house user to make sure it was suitable instructional material.

Comments

[Oracular Man]

which layout? activity_main.xml or content_main.xml?