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setContentView(R.layout.main); - cannot find package

I have never used Android Studio before and have always been coding using NetBeans.
I need to create an app for Android, so I decided to use NetBeans. I created new project and it is 'empty' for now, however I have an error:
package Fridge.Freezer;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
The error is in setContentView(R.layout.main); - cannot find package. Can anyone tell what I am doing wrong? Clean and build does not work.

erase your package name at the top and try to add it to getting the suggestion package import by shortcut Control + Enter beside "R"

Try checking following component in your project directory
R.java file
folder named layout
layout xml file named main.xmlmain
PS Since your are starting a fresh project, I would suggest you to start at Android Studio.

I tried cleaning the project and rebuilding it again. It did not work. The solution was to restart IDE.

React Native Android app white screen won't start

I get the following error log when I run my Android app: http://pastebin.com/1jHEfdQ3 The app sometimes crashes in the simulator but most of the time it just displays a white screen. I can console.log one or two things until the app won't respond. R-R to refresh doesn't work. None of the dev tools work. I'm stumped with what to do at this point.
I'm running react native 0.38.0
EDIT:
I've tried cleaning my gradle and deleting and reinstalling my node modules.
One thing to note is that I am using React Native Navigation which means I had to modify MainApplication and MainActivity to the following:
MainActivity:
package com.prayerrequest;
import com.facebook.react.ReactActivity;
import com.reactnativenavigation.NavigationApplication;
import com.airbnb.android.react.maps.MapsPackage;
import com.cmcewen.blurview.BlurViewPackage;
import io.realm.react.RealmReactPackage;
import com.reactnativenavigation.controllers.SplashActivity;
public class MainActivity extends SplashActivity {
}
MainApplication:
package com.prayerrequest;
import com.facebook.react.ReactPackage;
import com.cmcewen.blurview.BlurViewPackage;
import io.realm.react.RealmReactPackage;
import com.airbnb.android.react.maps.MapsPackage;
import com.reactnativenavigation.NavigationApplication;
import java.util.Arrays;
import java.util.List;
public class MainApplication extends NavigationApplication {
#Override
public boolean isDebug() {
// Make sure you are using BuildConfig from your own application
return BuildConfig.DEBUG;
}
#Override
public List<ReactPackage> createAdditionalReactPackages() {
return Arrays.<ReactPackage>asList(
new RealmReactPackage(),
new BlurViewPackage(),
new MapsPackage()
);
}
}
I've crossposted on React Native's issues page here

The issue seems to be 'Couldn't load memtrack module (No such file or directory)'
It looks like there's an issue with the simulator.
This is a config of my fully functional simulator:
Lots of other suggestions can be found here:
Couldn't load memtrack module Logcat Error

I had a similar problem. I would get this white screen when trying to get it to run on device.
The problem was when I would do adb devices or react-native run-android I would get "ADB is Not Recognized as an internal or external command".
So my fix was to add the path to adb.exe's parent directory to my Environment Variables and then restart my command prompts.I then ran react-native run-android and on startup no more red screen showing the completely useless error message Error calling AppRegistry.runApplication! :)
So I found ADB was located in my folder:
C:\Users\dell\AppData\Local\Android\sdk\platform-tools\adb.exe
I am on a Windows 10 system. dell is my user name of the computer.
So I went to System Environment Variables then found "Path" then clicked "Edit", then clicked "New" and added in "C:\Users\dell\AppData\Local\Android\sdk\platform-tools".

React Native Sqlite for android configuration

I am playing with react native for android and i have special interest with sqlite.
I try to use the sqlite lib here react-native-sqlite-storage buy i always have BUILD FAILED when "run-android". I'm a little lost at step 4 (How to use Android)
configuring the MainActivity
The error:
E:\Documents\Visual Studio CODE\MyApp\android\app\src\main\java\com\myapp\MainActivity.java:22: error: cannot find symbol
protected List getPackages() {
^
symbol: class List
location: class MainActivity
...
Have somebody a very simple sample project for android to see the correct conf?
thanks in advance.

You are missing import statement for the List.
import java.util.List;
#Override
protected List getPackages() {
//noinspection RedundantArrayCreation
return Arrays.asList(new ReactPackage[]{
new MainReactPackage(),
});
}
Any java IDE has some kind of fix import function so it would automatically propose you correct solution.
Try android studio it's free and react-native automatically generate gradle configuration. All you need to do is to import your project folder with gradle files (android by default) into IDE and press ctrl+space to turn IntelliSense on.

You should change MainAplication.java and not MainActivity.java

Android Testing with Robolectric: not recognizing Facebook SDK

We are trying to use the Robolectric testing framework in Android Studio in order to test the Facebook API. The Facebook Login button works so the Facebook API is working. However, the following test fails:
package com.airportapp.test.Models;
import android.app.Activity;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.robolectric.annotation.Config;
import org.robolectric.Robolectric;
import com.airportapp.test.MyRobolectricTestRunner;
import com.airportapp.LoginActivity;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
#RunWith(MyRobolectricTestRunner.class)
public class LoginActivityTest {
#Before
public void setup() {
//do whatever is necessary before every test
}
#Test
public void testActivityFound() {
Activity activity = Robolectric.buildActivity(LoginActivity.class).create().get();
Assert.assertNotNull(activity);
}
}
And the error is that Android Studio could not find the android.support file when we run the tests. You can see the error here:
The other error that shows up is:
android.view.InflateException: XML file app/src/main/res/layout/activity_login.xml line #-1 (sorry, not yet implemented): Error inflating class com.facebook.widget.LoginButton
So Android Studio is not happy with the facebook login button as well :( But it works... We think that we need to import something, but we don't know where to put it.

The InflateException is because Robolectric cannot find the resources from the Facebook SDK. To solve this, the project.properties file has to be updated to point to the Facebook SDK project. Do this by adding the following line to it:
android.library.reference.1={Path}
{Path} should be a relative path, from the project.properties file to the folder containing the AndroidManifest.xml of the Facebook SDK project. In my case that is ../../build/intermediates/exploded-aar/com.facebook.android/facebook/3.21.0.
Note that this works for all Android Library Projects which contain resources that aren't found by Robolectric. Further reading: here and here. Also, more documentation about project.properties can be found here. Note that in my project the Robolectric tests are located in the Android app project itself. So you could also try placing the project.properties file in the same directory as the AndroidManifest.xml used for testing.
As for your first problem; I have no personal experience with it. But it appears to be because Gradle cannot find the support libraries when compiling the unit tests. The answer from this question should fix it.

Android App Error unknownpackageerror

I am creating simple android application in android of hello world printing and getting an -- error Description
Resource Path Location Type Error generating final archive: java.lang.ArrayIndexOutOfBoundsException: 13 Demo_ABC Unknown Android Packaging Problem
Code is:
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
public class MainActivity extends Activity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}

Someone else had the same problem with eclipse. The solution was to check the box "Create Test Project":
Your project is getting associated with some Test Project which you are not mapping with your newly created project. When you are creating any new project check carefully whether you are including the "Create Test Project" option or not.
Another guess: As the error seems to be package-related and your code does not include that, insert the correct package yourpackage.tld; in the code. (you said "Code is:").
Maybe that is missing Android expects it by default and gives weird errors because that was totally unforseen by the Google Android developers.