Jeff Jeff - 20 days ago 6
Android Question

Android Studio cannot find symbol variable

I installed Android Studio about two days ago, I also installed the most updated version of Java and JDK 1.8 (I think it was Java SE 8u101). I am able to edit code and I'm following a tutorial from the official Android Studio website. (Here: https://developer.android.com/training/basics/firstapp/building-ui.html)

However, upon hitting run I've gotten the two following errors:


  1. Error:(24, 57) error: cannot find symbol variable activity_display_message


    Code for this:


    ViewGroup layout = (ViewGroup) findViewById(R.id.activity_display_message);


  2. Error:(33, 25) error: cannot find symbol variable EXTRA_MESSAGE


    Code for this:


    intent.putExtra(EXTRA_MESSAGE, message);




What might I be doing wrong? The emulator pops up and I can get to other apps on the phone but I just can't get my app to load. Should I have installed Java SE 8u102 instead?

I also got a second error message:


Error:Execution failed for task ':app:compileDebugJavaWithJavac'. > Compilation failed; see the compiler error output for details.


Any help is appreciated.

Below is my code for the first xml file, "activity_main.xml":

<?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:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText android:id="@+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="@string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_send"
android:onClick="sendMessage" />
</LinearLayout>


Below is my code for "activity_display_message.xml"

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.appno1.DisplayMessageActivity">

</RelativeLayout>

Answer

I think you might lose the last note in the tutorial. android note description

so you just add android:id attribute to the activity_display_message.xml file and it will be ok!oh actually you should add into the layout element which is the valid location.

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