Google Android tutorial - not compiling

Question

I did everything just as stated in this tutorial: google android basic tutorial and despite everything being done just as described, the code refuses to compile with 3 errors. Looks like the guys writing the turorial forgot to mention what are those things and where/how do I define them.

The errors I get:

Error:(24, 68) error: cannot find symbol variable container
Error:(36, 23) error: cannot find symbol variable action_settings
Error:(46, 54) error: cannot find symbol variable fragment_display_message

Neither of the 3 fields are defined anywhere (Perhaps one of the libraries is wrong?) The file in question is:

package com.example.asteroth.first;

import android.app.Activity;
import android.app.Fragment;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.*;
import android.widget.TextView;
import android.R;

public class DisplayMessageActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Intent intent = getIntent();
        String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
        TextView textView = new TextView(this);
        textView.setTextSize(40);
        textView.setText(message);
        setContentView(textView);
//        setContentView(R.layout.activity_display_message);
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
        }

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public static class PlaceholderFragment extends Fragment {
        public PlaceholderFragment() { }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_display_message, container, false);
            return rootView;
        }
    }
}

I am using Android Studio I just downloaded and no question from search or Similar Questions points at the problem like this one, hence I suspect authors of tutorial forgot to mention something minor. I've seen suggestion to place the "container" as a new ID in one of the XML files, but to no avail.

EDIT: 'cannot find symbol ActionBarActivity' following Android Development Tutorial? This post suggest a solution, however it changes ActionBarActivity to just Activity which is very different from what the tutorial uses and I don't know how serious repercussions would it cause

EDIT2: Problems found and removed: import android.R //causes action_settings error container missing //had to add it in the xml file as an id xml file named wrong //If I got that correctly, I'm still waiting for someone experienced to clarify, but seems like the tutorial used different name for the xml file then the one that the java code references

Remaining problem is similar to this one Cannot resolve method placeholderfragment error however, I both extend Fragment and include android.app.Fragment as can be seen in the included file.

Answer 1

I tried the same tutorial and here is how I fixed my errors:

R.id.container cannot be resolved error

I had to import android.support.v4.app.Fragment to fix this problem and add android:id = "@+id/container" to the RelativeLayout section in my activity_display_message.xml file.

fragment_display_message cannot be resolved error

Change R.layout.fragment_display_message to R.layout.activity_display_message instead. There is no need for creating a new xml file for fragment_display_message.

This should fix these two errors.

But you would probably be better off if you comment out the if(savedInstanceState............ statement as otherwise your program would crash once you try to run it if it doesn't give you any errors.

Your onCreate method should look like this:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.activity_display_message);
    Intent intent=getIntent();
    String message=intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
    TextView textView=new TextView(this);
    textView.setTextSize(40);
    textView.setText(message);

    setContentView(textView);

    /*if (savedInstanceState==null){
        getSupportFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
    }*/
}

Answer 2

I'm doing the tutorial for the first time now on Feb. 23, 2015 and ran into this compilation error though I feel like I've closely followed the steps. I changed fragment_display_message to activity_display_message which is an XML file they have us create in the tutorial. This seems to solve the error, and allow the app to run.

// A placeholder fragment containing a simple view.
public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() { }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.activity_display_message,
                container, false);
        return rootView;
    }
}

Answer 3

It's a copy paste error. If you paste code with "R." in it, the development environment always imports the android.R:

import android.R;

If you use R.id.... it is always looking up the android.R and not your own generated R class. Delete the import and it should be fine. This general works for me.

After that you have to check if you already defined the id's and layout. You can check Layouts by looking on the package explorer under res->layout . In your example there has to be an fragment_display_message.xml in it.

For id's you have to look up all of your layouts and check if there are the specific views like the container .

Answer 4

Add this line to take care of your first error: android:id = "@+id/container" You get that error because container isn't in the XML.

Add <string name="action_settings">Action Settings</string> so that the "Action settings" which I'm assuming doesn't exist in your XML code since you have that error.

Create your own XML file with this exact name fragment_display_message.xml to handle that error and check what code you might need to insert into it in your google tutorial. Often times with Eclipse, these files are not included for reasons outside my knowledge. So you have to create them or insert them yourself. (Make sure you have the latest version of the SDK by the way.

EDIT: Be sure to have the correct imports matching with your "tutorial". I took a gander at it and see you missing two imports. One of which another user answered.

Answer 5

I got a similar error on the Building a Simple User Interface step:

Error:(18, 54) error: cannot find symbol variable toolbar

I've narrowed the cause down to res/layout/activity_my.xml:

<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="@string/edit_message" />
<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/button_send" />

The original version that did compile (but no button or text box) is:

<?xml version="1.0" encoding="utf-8"?>

xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:fitsSystemWindows="true"
tools:context=".MyActivity">

<android.support.design.widget.AppBarLayout android:layout_height="wrap_content"
    android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar android:id="@+id/toolbar"
        android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

<include layout="@layout/content_my" />

<android.support.design.widget.FloatingActionButton android:id="@+id/fab"
    android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email" />

Answer 6

fragment_display_message Make sure you have a file named fragment_display_message.xml in your res/layout folder.

action_settings Make sure you have that item in your menu.xml file in res/menu

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=
           ".MenuExampleActivity" >
    <item
        android:id="@+id/action_settings"
        android:orderInCategory="1"
        app:showAsAction="never"
        android:title="My menu option"/>
</menu>

container Make sure you have a layout (ex. RelativeLayout) with the id set to "container" in your activity_main.xml file in res/layout, given that it's the reference for the code to insert the fragment there.