This is a comparison between the lifecycle of  Android vs iOS:

![enter image description here][1]


* **Note**: viewDidUnload is deprecated after iOS 6 

  [1]: http://i.stack.imgur.com/Jn6MZ.png

I&#39;m running a clean install of Ruby 2.2.1 on Windows 8.1 with DevKit. After the installation I run:

    gem install rails
    rails new testapp
    cd testapp
    rails server

leaving everything else at default.

The process fails at the last line when, instead of running the server, I get the error message 

    in &#39;require&#39;: cannot load such file -- &#39;nokogiri\nokogiri&#39; (LoadError)

It happens every time and I&#39;ve looked around and tried everything I found to fix it, but nothing so far has worked.

What is the problem here and how do I get a simple test Rails app to work?


&#39;require&#39;: cannot load such file -- &#39;nokogiri\nokogiri&#39; (LoadError) when running `rails server`

![enter image description here][1]


  [1]: http://i.stack.imgur.com/mHexZ.gif


two objects in the scene.
the cube rotate axis should be the cube&#39;s center,that&#39;s my expect.

but the shoe model&#39;s rotate axis is the world&#39;s y axis.

my original code is.

    cube.rotation.y += 0.01;
    shoe.rotation.y += 0.01;

I found a solution in stackoverflow,like this:

    cube.rotation.y += 0.01;
    var pivot = new THREE.Object3D();
    pivot.add(shoe);
    pivot.rotation.y += 0.01;

But it doesn&#39;t work.
And then, I change the shoe&#39;s position. 

    cube.rotation.y += 0.01;
    var pivot = new THREE.Object3D();
    shoe.position.set(-5,0,0);
    pivot.add(shoe);
    pivot.rotation.y += 0.01;

The result is better now, but it still not perfect. And since there are a lot of shoe&#39;s model, I can&#39;t determine different position for every shoe model.

threejs how to rotate around object&#39;s own center,instead of world center

Actually, I would say that both iOS `ViewControllers` and Android `Activities` have their lifecycle methods. For example an equivalent of `ViewController.viewDidLoad()` is `Activity.onCreate()` ?

Else I still need to know the equivalent of the other :

 - `OnStart()`
 - `OnRestart()`
 - `OnResume()`
 - `OnStop()`
 - `OnDestroy()`
 - `OnPause()`


What the equivalent of activity life cycle in iOS?

<p>Actually, I would say that both iOS <code>ViewControllers</code> and Android <code>Activities</code> have their lifecycle methods. For example an equivalent of <code>ViewController.viewDidLoad()</code> is <code>Activity.onCreate()</code> ?</p>
<p>Else I still need to know the equivalent of the other :</p>
<ul>
<li><code>OnStart()</code></li>
<li><code>OnRestart()</code></li>
<li><code>OnResume()</code></li>
<li><code>OnStop()</code></li>
<li><code>OnDestroy()</code></li>
<li><code>OnPause()</code></li>
</ul>


I would like to know how to ignore exceptions and continue infinite stream (in my case stream of locations)?

I&#39;m fetching current user position (using [Android-ReactiveLocation](https://github.com/mcharmas/Android-ReactiveLocation)) and then sending them to my API (using [Retrofit](http://square.github.io/retrofit/)). 

In my case, when exception occurs during network call (e.g. timeout) `onError` method is invoked and stream stops itself. How to avoid it?

Activity:

    private RestService mRestService;
    private Subscription mSubscription;
    private LocationRequest mLocationRequest = LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(100);
    ...
    private void start() {
        mRestService = ...;
        ReactiveLocationProvider reactiveLocationProvider = new ReactiveLocationProvider(this);
        mSubscription = reactiveLocationProvider.getUpdatedLocation(mLocationRequest)
                .buffer(50)
                .flatMap(locations -&gt; mRestService.postLocations(locations)) // can throw exception
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe();
    }

RestService:

    public interface RestService {
        @POST(&quot;/.../&quot;)
        Observable&lt;Response&gt; postLocations(@Body List&lt;Location&gt; locations);
    }

   


How to ignore error and continue infinite stream?

I know there are no default selection methods in the `RecyclerView` class, but I have tried in the following way:

    public void onBindViewHolder(ViewHolder holder, final int position) {
        holder.mTextView.setText(fonts.get(position).getName());
        holder.checkBox.setChecked(fonts.get(position).isSelected());

        holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                if(isChecked) {
                    for (int i = 0; i &lt; fonts.size(); i++) {
                        fonts.get(i).setSelected(false);
                    }
                    fonts.get(position).setSelected(isChecked);
                }
            }
        });
    }

While trying this code, I got the expected output, but not completely.

I will explain this with images.

By default, the first item is selected from my adapter.

![][1]

Then I select the 2nd, then the 3rd, then the 4th and finally the 5th one.

![][2]

Here only the 5th should be selected, but all five are getting selected.

If I scroll the list to the bottom and come again to the top, I get what I expect.

![][3]

How can I overcome this issue? And sometimes if I scroll the list very fast, some other item gets selected. How can I overcome this problem too?

While I was trying to use `notifyDataSetChanged()` after `fonts.get(position).setSelected(isChecked);`, I got the following exception:

    java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling
            at android.support.v7.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:1462)
            at android.support.v7.widget.RecyclerView$RecyclerViewDataObserver.onChanged(RecyclerView.java:2982)
            at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyChanged(RecyclerView.java:7493)
            at android.support.v7.widget.RecyclerView$Adapter.notifyDataSetChanged(RecyclerView.java:4338)
            at com.app.myapp.screens.RecycleAdapter.onRowSelect(RecycleAdapter.java:111)

  [1]: http://i.stack.imgur.com/M6HlK.png
  [2]: http://i.stack.imgur.com/SyeRP.png
  [3]: http://i.stack.imgur.com/CW5sX.png





Single selection in RecyclerView

Not getting any errors and all the data seems valid. For some reason, nether of the view related methods are being called. I have made sure of the following:

- getItemCount() is the only adapter method being called and is returning a positive integer value, (I know this will be the area you guys will look at)

 - Constructor is being called, member variables are valid.

 - Parent View is a vertical LinearLayout; no scrollview, or any other view with their own scroll properties in sight.

 - containing fragment view is created and shown on screen.

Here is the declaration in the fragment followed by the adapter. Any help would be appreciated as this has be completely baffled.

    SubMenuAdapter adapter = new SubMenuAdapter(getActivity(), mContentItems);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(adapter);


&lt;!-- language: java --&gt;

    public class SubMenuAdapter extends RecyclerView.Adapter&lt;SubMenuAdapter.ViewHolder&gt; {
    private static final String TAG = String.format(&quot;==&gt; %S&quot;, SubMenuAdapter.class.getSimpleName());

    private final List&lt;ContentItem&gt; mContentItems;
    private Context mContext;

    public SubMenuAdapter(Context context, List&lt;ContentItem&gt; contenItems) {
        Log.d(TAG, &quot;Constructor called&quot;);
        mContentItems = contenItems;
        mContext = context;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        Log.d(TAG, &quot;onCreateViewHolder called&quot;);
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_resource_efficiency, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Log.d(TAG, &quot;onBindViewHolder called&quot;);

        ContentItem item = mContentItems.get(position);
        holder.textName.setText(item.getName());
        FontSetter.setMyriadProRegular(mContext, holder.textName);
        Picasso.with(mContext).load(&quot;file://&quot; + item.getPreviewImageDefault()).into(holder.imageIcon);
    }

    @Override
    public int getItemCount() {
        Log.d(mContext, String.format(&quot;getItemCount: %d&quot;, mContentItems.size()));
        return mContentItems.size();
    }

    // ViewHolder
    public static class ViewHolder extends RecyclerView.ViewHolder {

        TextView textName;
        ImageView imageIcon;

        public ViewHolder(View view) {
            super(view);
            textName = (TextView) view.findViewById(R.id.tv_resource_efficiency_option);
            imageIcon = (ImageView) view.findViewById(R.id.iv_resource_efficiency_icon);
        }
    }

RecyclerView not calling onCreateViewHolder or onBindView

Upon a user&#39;s sign out from my app I am clearing everything that may have been cached previously from the webview by calling this method:  

     public void clearCookiesAndCache(Context context){
        CookieSyncManager.createInstance(context);
        CookieManager cookieManager = CookieManager.getInstance();

        if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.LOLLIPOP) {
            cookieManager.removeAllCookies(null);
        }
        else {
            cookieManager.removeAllCookie();
        }        
    }

CookieSyncManager is marked as deprecated, however. CookieSyncManager.createInstance(context) is necessary to be called, however, if you have not loaded the webview previously. So how are we supposed to clear the cookies and cache without using the deprecated CookieSyncManager in cases where the webview may not have been previously loaded?

How to clear cookies and cache of webview on Android when not in webview?

Is there a way to add a simple header/footer to a RecyclerView?&lt;br&gt; 
&lt;br&gt;
Here you can see what I&#39;ve got. The first Card touches the Toolbar
![This is what I&#39;ve got][1]&lt;br&gt;&lt;br&gt;
And here you can see what I want. 8dp Padding between the bottom and the Card. 
![This is what I want to have][2]
&lt;br&gt; &lt;br&gt;

Methods I tried so far:

&lt;li&gt; Use a header view in my recyclerview. But I think it is very unefficient to do this for every recyclerview.&lt;/li&gt;
&lt;br&gt;
&lt;li&gt; use a 8dp top margin which results in the problem that the recyclerview has white bars on top/bottom when scrolling.&lt;/li&gt;
&lt;br&gt;&lt;li&gt;
add a padding to the list item which results in different margins between the outer and inner cards.&lt;/li&gt;
&lt;br&gt;

I&#39;m sure that there is a simple solution which I don&#39;t know so far.

  [1]: http://i.stack.imgur.com/YyLxHl.png
  [2]: http://i.stack.imgur.com/dotAxl.png

How to add a simple 8dp header/footer to Android&#39;s RecyclerView?

So I have been making an app, and everything has been working great. But today I made a new class like usual and for some reason in this class I can&#39;t access Public/Global variable from other classes. All the other classes can, but now when ever I try to make a new class I can&#39;t. How would this be fixed?

I am using Swift and Xcode 6.

Working Class:

    import UIKit
    import Foundation
    import Parse
    import CoreData

    var signedIn = true

    class ViewController: UIViewController {

New Class:

    import UIKit

    class NewClass: UIViewController {

        override func viewDidLoad() {
            super.viewDidLoad()

            signedIn = false
        
    }

But on `signedIn = false`

I get the error: 

&gt; use of unresolved identifier &quot;signedIn&quot;

&#39;Use of Unresolved Identifier&#39; in Swift

In IOS8 Safari there is a new bug with position fixed.

If you focus a textarea that is in a fixed panel, safari will scroll you to the bottom of the page. 

This makes all sorts of UIs impossible to work with, since you have no way of entering text into textareas without scrolling your page all the way down and losing your place. 

Is there any way to workaround this bug cleanly? 

&lt;!-- language: lang-css --&gt;

    #a {
      height: 10000px;
      background: linear-gradient(red, blue);
    }
    #b {
      position: fixed;
      bottom: 20px;
      left: 10%;
      width: 100%;
      height: 300px;
    }

    textarea {
       width: 80%;
       height: 300px;
    }

&lt;!-- language: lang-html --&gt;

    &lt;html&gt;
       &lt;body&gt;
       &lt;div id=&quot;a&quot;&gt;&lt;/div&gt;
       &lt;div id=&quot;b&quot;&gt;&lt;textarea&gt;&lt;/textarea&gt;&lt;/div&gt;
       &lt;/body&gt;
    &lt;/html&gt;

Safari in ios8 is scrolling screen when fixed elements get focus

I have a grouped UITableview which is created programatically. Also I have a cell with xib file populated in tableview programmatically as well. So far so good. But I want to only remove outer separator line. I used below code but this time removed all separator line. 

&gt; self.tableView.separatorColor = [UIColor clearColor];

this is not good option for my situation. Here is the screenshot what i want to do;

![enter image description here][1]


  [1]: http://i.stack.imgur.com/nNUTQ.png

Grouped UITableview remove outer separator line

I created an app and I am attempting to allow the user to continue to listen to their music while playing my game, but whenever they hit &quot;play&quot; and the ingame sounds occur it will stop the background music.  I am developing on iOS using Swift. Here is a piece of the code that initiates the ingame sounds.

    func playSpawnedDot() {
        var alertSound: NSURL = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource(&quot;spawnDot&quot;, ofType: &quot;mp3&quot;)!)!
        var error:NSError?
        audioPlayer = AVAudioPlayer(contentsOfURL: alertSound, error: &amp;error)
        audioPlayer.prepareToPlay()
            
        if volumeBool {
            audioPlayer.play()
        }
    }

How can I allow background music to continue playing while my app still plays its sounds while using Swift

I am trying to access the `MyCustomView` from another class using the following code in ViewController.swift ..

    var view = MyCustomView(frame: CGRectZero)

.. in the `viewDidLoad` method. The problem is the view does not get initialized in the simulator.

I have already set class in storyboard for the current ViewController.


    class MyCustomView: UIView {
        var label: UILabel = UILabel()
        var myNames = [&quot;dipen&quot;,&quot;laxu&quot;,&quot;anis&quot;,&quot;aakash&quot;,&quot;santosh&quot;,&quot;raaa&quot;,&quot;ggdds&quot;,&quot;house&quot;]
        
        override init(){
            super.init()
        }
        
        override init(frame: CGRect) {
            super.init(frame: frame)
            self.addCustomView()
        }
        
        required init(coder aDecoder: NSCoder) {
            fatalError(&quot;init(coder:) has not been implemented&quot;)
        }
        
        func addCustomView() {
            label.frame = CGRectMake(50, 10, 200, 100)
            label.backgroundColor=UIColor.whiteColor()
            label.textAlignment = NSTextAlignment.Center
            label.text = &quot;test label&quot;
            label.hidden=true
            self.addSubview(label)
            
            var btn: UIButton = UIButton()
            btn.frame=CGRectMake(50, 120, 200, 100)
            btn.backgroundColor=UIColor.redColor()
            btn.setTitle(&quot;button&quot;, forState: UIControlState.Normal)
            btn.addTarget(self, action: &quot;changeLabel&quot;, forControlEvents: UIControlEvents.TouchUpInside)
            self.addSubview(btn)
            
            var txtField : UITextField = UITextField()
            txtField.frame = CGRectMake(50, 250, 100,50)
            txtField.backgroundColor = UIColor.grayColor()
            self.addSubview(txtField)
        }


How to create custom view programmatically in swift having controls text field, button etc

I am trying to convert this `Obj-C` code to `Swift` code but I don&#39;t know what the equivalent of this code should be ?

    #define DEGREES_TO_RADIANS(degrees)((M_PI * degrees)/180)

I googled and found [this][1]

But I don&#39;t understand how to convert that in Swift in my case?


  [1]: https://stackoverflow.com/questions/24325477/how-to-use-a-objective-c-define-from-swift

How can I convert from degrees to radians?

I&#39;m currently in the process of submitting my first app to the Apple store.
I&#39;ve completed the following processes

 1. Obtained a developer account
 2. Logged into the Member Center to Create an App ID
 3. Used keychain access to request and receive a distribution certificate
 4. Obtained a provisioning profile using my id and certificate

When I build the app it runs perfectly in the app simulator and on the actual ipad, however when I switch my app to `Archive` on iOS Device i have a major code sign error which i&#39;ve attached below.

    codesign /Users/Gaby/Library/Developer/Xcode/DerivedData/RoyalAppInspection-dthvtpxadkslqmhkwdpaqkyujscg/Build/Products/Debug-iphoneos/RoyalAppInspection.app
    cd /Users/Gaby/Desktop/RoyalAppInspection
    export CODESIGN_ALLOCATE=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/codesign_allocate
    export PATH=&quot;/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin


    /usr/bin/codesign --force --sign 79640A11C8D22589BD337496ABB8443581513846 --entitlements /Users/Gaby/Library/Developer/Xcode/DerivedData/RoyalAppInspection-dthvtpxadkslqmhkwdpaqkyujscg/Build/Intermediates/RoyalAppInspection.build/Debug-iphoneos/RoyalAppInspection.build/RoyalAppInspection.app.xcent /Users/Gaby/Library/Developer/Xcode/DerivedData/RoyalAppInspection-dthvtpxadkslqmhkwdpaqkyujscg/Build/Products/Debug-iphoneos/RoyalAppInspection.app
    
    79640A11C8D22589BD337496ABB8443581513846: no identity found Command /usr/bin/codesign failed with exit code 1

I have no idea what to do to fix this, as I&#39;ve tried to make sure all the other aspects of the process were completed correctly.

One concern i did have was when i clicked the provisioning profile file it would not open and &quot;add to library&quot; wouldn&#39;t pop up (i cannot access iphone configuration utility for some reason.) I manually added the .mobileprovision file to my xcode project but i&#39;m thinking this may also be a source of my error.

Anyone, can you please help?

command/usr/bin/codesign failed with exit code 1- code sign error

I am a little fuzzy about Core Data Relationships deletion rules. So if someone could help me answer a few questions about them.

I have Entities A and B. A has a to-Many relationship with B, and B has a to-One relationship with A.

A&lt;---&gt;&gt;B

Now, if I set the delete rule at A to Cascade, I understand it will delete all the Bs related to it. But if I set it to Nullify, will it set the Bs to NIL or just the Foreign Key to Nil?

And I looked everywhere about the relationship from B to A, should I set it to Nullify? Will that just Nullate the &quot;B Object&quot; at A? Or will it Nullify all the Bs associated with A? What about Cascade? Will it delete all the Bs associated with A, or just the particular B?

Or do I just use &quot;No Action&quot; on the relation from B to A so that when I delete B, no change will happen to A, but the reference to B won&#39;t exist?

I am PRETTY confused with these, so excuse my questions.

Thanks.

Understanding Core Data delete rules on One to Many

I&#39;m using storyboards for the first time in my app

When I close Xcode, I have 0 warnings about misplaced views or anything pertaining to my storyboard. When I restart Xcode and open the storyboard, 3 out of my 15 scenes have misplaced view warnings.

Without touching anything (other than selecting the file), I can issue a `git status` and see that the .storyboard file has changes. If I `git diff`, I see this included in multiple areas of the file:

    &lt;variation key=&quot;widthClass=compact&quot; misplaced=&quot;YES&quot;&gt;
        &lt;rect key=&quot;frame&quot; x=&quot;8&quot; y=&quot;56&quot; width=&quot;130&quot; height=&quot;34&quot;/&gt;
    &lt;/variation&gt;

If an element already had `&lt;variation key=&quot;widthClass=Compact&quot;` node, then the `misplaced` attribute and `rect` node are added.

The only thing I have to do to get the warnings to go away is click on each one, make sure &quot;Update Frame&quot; is selected, and click &quot;Fix Misplacement&quot;. That fixes everything until I restart Xcode.

The basic structure of my scene is:
    
    UIView
        UICollectionView
            UICollectionReusableView
            UICollectionViewCell
            UICollectionViewCell
        UISegmentedControl
            

How can I prevent this from happening each time I restart?

Misplaced views each time Xcode restarts

I&#39;m trying to map some Java classes using the Hibernate JPA implementation. My problem is that I can&#39;t use hardcoded Strings als column namens. You can see the error message I get in the picture below.


![enter image description here][1]


I&#39;m using OpenJPA as my Default JPA Provider and have already tried to change it.

IntelliJ Version 14.0.3


regards,


  [1]: http://i.stack.imgur.com/YRUbK.png

JPA Cannot resolve column/IntelliJ

I am using gulp. 

I would like to having one or multiple JS files (say jQuery) to combine them in one, minify it, and write it to a distribution folder. 

This is how I do it: 

    minifyJS([&#39;/js/myModule.file1.js&#39;,
              &#39;/js/myModule.file2.js&#39;], &#39;/dist/js&#39;, &#39;myModule&#39;)

the function: 

    function minifyJS(sourceFiles, destinationFolder, filenameRoot) {
        return gulp.src(sourceFiles)
            .pipe(plumber())
    
            // .pipe(sourcemaps.init()) here ???
            .pipe(concat(filenameRoot + &#39;.js&#39;))
            .pipe(sourcemaps.init()) // or here ???
    
            .pipe(gulp.dest(destinationFolder)) // save .js
            .pipe(uglify({ preserveComments: &#39;license&#39; }))
            .pipe(rename({ extname: &#39;.min.js&#39; }))
            .pipe(gulp.dest(destinationFolder)) // save .min.js
            .pipe(sourcemaps.write(&#39;maps&#39;))
            .pipe(gulp.dest(destinationFolder)) // save .map
    }


What I am not sure about is the `sourcemaps.init()` location...   

Should I create multiple (2 in my case) map files (that would be nice if is supported by browsers) or only one (*/maps/myModule.map*)?

gulp: uglify and sourcemaps

Currently there are two main popular Java Object to Object mapping frameworks that supersede Dozer (http://dozer.sourceforge.net/documentation/mappings.html), they are: 

 1. Selma - http://www.selma-java.org/
 2. MapStruct - http://mapstruct.org/

With the exception of this page (http://vytas.io/blog/java/java-object-to-object-mapping-which-framework-to-choose-part-2/) I haven&#39;t been able to find much online regarding which framework is better than the other, or under what circumstances they are better. Wondering if anyone you can shed some light on this. In terms of functionality based on the documents, they seem to be doing the same thing.

Java mapping: Selma vs MapStruct

Hi all I am trying to create schema Test. 

    PUT /test
	{
        &quot;mappings&quot;: {
            &quot;field1&quot;: {
                &quot;type&quot;: &quot;integer&quot;
            },
            &quot;field2&quot;: {  
                &quot;type&quot;: &quot;integer&quot;
            },
            &quot;field3&quot;: {
                &quot;type&quot;: &quot;string&quot;,
                &quot;index&quot;: &quot;not_analyzed&quot;
            },
            &quot;field4&quot;: {
                &quot;type&quot;: &quot;string&quot;,
                &quot;analyzer&quot;: &quot;autocomplete&quot;,
                &quot;search_analyzer&quot;: &quot;standard&quot;
            }
        },
        &quot;settings&quot;: {
    	    bla
    	    bla
    	    bla
    	}
    }




I am getting the following error

    {
        &quot;error&quot;: {
            &quot;root_cause&quot;: [{
    	        &quot;type&quot;: &quot;mapper_parsing_exception&quot;,
        		&quot;reason&quot;: &quot;Root mapping definition has unsupported parameters: [index : not_analyzed] [type : string]&quot;
        	}],
    	    &quot;type&quot;: &quot;mapper_parsing_exception&quot;,
        	&quot;reason&quot;: &quot;Failed to parse mapping [featured]: Root mapping definition has unsupported parameters:  [index : not_analyzed] [type : string]&quot;,
        	&quot;caused_by&quot;: {
        	    &quot;type&quot;: &quot;mapper_parsing_exception&quot;,
        		&quot;reason&quot;: &quot;Root mapping definition has unsupported parameters:  [index : not_analyzed] [type : string]&quot;
        	}
        },
        &quot;status&quot;: 400
    }


Please help me to resolve this error

Elasticsearch : Root mapping definition has unsupported parameters index : not_analyzed

I&#39;ve been looking everywhere: stackoverflow, automapper documentation, internets and just couldn&#39;t find any info on this one, even tho this seems to be a very common problem.

My mapping:

    CreateMap&lt;StatusLevelDTO, StatusLevel&gt;()
                .ForAllMembers(opt =&gt; opt.Condition(src =&gt; src != null));
This doesn&#39;t work because src represents source object (StatusLevelDTO), not a source property (I think).

To be more specific, If I map ObjectA to ObjectB, ObjectA.SomeValue is null and ObjectB.SomeValue is 2, I want the destination object to keep its value (2).

I&#39;ve seen this question: https://stackoverflow.com/questions/20021633/automapper-skip-null-values-with-custom-resolver and tried the first two answers but they both seem to be outdated for version 6.

Is there any way to make this happen in Automapper 6? I am using 6.0.2 to be exact.

How to ignore null values for all source members during mapping in Automapper 6?

I&#39;m requesting images from presenter in adapter:

      @Override
      public void onBindViewHolder(SiteAdapter.ViewHolder holder, int position)
      {
        Site site = sites.get(position);
        holder.siteName.setText(site.getName());
        requestHolderLogo(holder, site.getLinks().getLogoUrl());
      }
    
      private void requestHolderLogo(final ViewHolder holder, final String logoUrl)
      {
        compositeSubscription.add(
          presenter.bitmap(logoUrl)
            .subscribe(
              bitmap -&gt; {
                holder.siteLogo.setImageBitmap(bitmap);
                holder.siteLogo.setVisibility(View.VISIBLE);
              },
              error -&gt; {
                holder.siteName.setVisibility(View.VISIBLE);
              })
        );
      }

I should unsubscribe when `ViewHolder` is re-used. It is easy.

But how stop all subscription when view is destroyed? I should also probably nullify presenter reference to avoid memory leak

What is lifecycle for RecyclerView adapter?

I have a ViewModel class just like the one defined in the **Connecting ViewModel and repository** section of [Architecture guide][1]. When I run my app I get a runtime exception. Does anyone know how to get around this? Should I not be injecting the ViewModel? Is there a way to tell the `ViewModelProvider` to use Dagger to create the model?


&lt;!-- language: lang-java --&gt;

    public class DispatchActivityModel extends ViewModel {

        private final API api;

        @Inject
        public DispatchActivityModel(API api) {
            this.api = api;
        }
    }

&gt;    Caused by: java.lang.InstantiationException: java.lang.Class&lt;com.example.dispatch.DispatchActivityModel&gt; has no zero argument constructor
        at java.lang.Class.newInstance(Native Method)
        at android.arch.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:143)
        at android.arch.lifecycle.ViewModelProviders$DefaultFactory.create(ViewModelProviders.java:143)&#160;
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:128)&#160;
        at android.arch.lifecycle.ViewModelProvider.get(ViewModelProvider.java:96)&#160;
        at com.example.base.BaseActivity.onCreate(BaseActivity.java:65)&#160;
        at com.example.dispatch.DispatchActivity.onCreate(DispatchActivity.java:53)&#160;
        at android.app.Activity.performCreate(Activity.java:6682)&#160;
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)&#160;
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2619)        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2727)&#160;
        at android.app.ActivityThread.-wrap12(ActivityThread.java)&#160;
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1478)&#160;
        at android.os.Handler.dispatchMessage(Handler.java:102)&#160;
        at android.os.Looper.loop(Looper.java:154)&#160;
        at android.app.ActivityThread.main(ActivityThread.java:6121)

  [1]: https://developer.android.com/topic/libraries/architecture/guide.html

Android lifecycle library ViewModel using dagger 2

I&#39;m trying to create an app that lets users log routes (locations/GPS). To ensure locations are logged even when the screen is off, I have created a `foreground service` for the location logging. I store the locations in a `Room Database` which is injected into my service using `Dagger2`.

However, this service is killed by Android which is, of course, not good. I could subscribe to low memory warnings but that doesn&#39;t solve the underlying problem of my service getting killed after ~30 minutes on a modern high-end phone running Android 8.0

I have created a minimal project with only a &quot;Hello world&quot; activity and the service: https://github.com/RandomStuffAndCode/AndroidForegroundService

The service is started in my `Application` class, and route logging is started through a `Binder`:

	// Application
	@Override
    public void onCreate() {
        super.onCreate();
        mComponent = DaggerAppComponent.builder()
                .appModule(new AppModule(this))
                .build();

        Intent startBackgroundIntent = new Intent();
        startBackgroundIntent.setClass(this, LocationService.class);
        startService(startBackgroundIntent);
    }

	// Binding activity
	bindService(new Intent(this, LocationService.class), mConnection, Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT);
	// mConnection starts the route logging through `Binder` once connected. The binder calls startForeground()

I probably don&#39;t need the `BIND_AUTO_CREATE` flag, I&#39;ve been testing different flags in an attempt to not get my service killed - no luck so far.

Using the profiler it does not seem like I have any memory leaks, memory usage is stable at ~35mb:

[![profiler][1]][1]

Using `adb shell dumpsys activity processes &gt; tmp.txt` i can confirm that `foregroundServices=true` and my service is listed 8th in the LRU list:

`Proc # 3: prcp  F/S/FGS  trm: 0 31592:com.example.foregroundserviceexample/u0a93 (fg-service)`

It seems like it is not possible to create a foreground service that you can trust to not get killed. So what can we do? Well...

1. Put the service in a separate process, in an attempt to let Android kill the UI/Activities while leaving the service alone. Would probably help, but doesn&#39;t seem like a guarantee
2. Persist *everything* in the service in e.g. a Room database. Every variable, every custom class, every time any of the changes and then start the service with `START_STICKY`. This seems kind of wasteful and doesn&#39;t lead to very beautiful code, but it would probably work... somewhat. Depending on how long it takes for Android to re-create the service after killing it, a large portion of locations may be lost.

Is this really the current state of doing stuff in the background on Android? Isn&#39;t there a better way?

EDIT: Whitelisting the app for battery optimization (disabling it) does not stop my service from being killed

EDIT: Using `Context.startForegroundService()` to start the service does not improve the situation

EDIT: So this indeed only occurs on *some* devices, but it occurs consistently on them. I guess you have to make a choice of either not supporting a huge number of users or write really ugly code. Awesome.


  [1]: https://i.stack.imgur.com/R5QGQ.png

Minimal android foreground service killed on high-end phone

Are ViewModels independent of activity/fragment lifecycles or just their configuration changes. When will they cease to exist and the subsequent onCleared() method called. 
Can the viewModel be shared with another Activity ?

A situation:

    Activity1+viewModel1---&gt;(rotation)---&gt;Activity1+viewModel1
    ---&gt;(launch Intent)---&gt;Activity2+viewModel1

is this sharing possible and is it a good practice.




Also, since the app lifecycle callbacks, onPause-&gt;onStop-&gt;onDestroy is same for both 

1.activity rotating and 

2.when an Activity ends, 

how is a ViewModel figuring out internally the right time to call onCleared and finally end its lifecycle. 



------------------------
**Findings**:

*the ViewModel uses a holderFragment internally to hold an instance of the activity and uses the setRetainInstance method like fragments to account for configuration changes.*

[Source: **dive-inside-of-androids-viewmodel-architecture-components**][2]

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/rESXi.png
  [2]: https://android.jlelse.eu/deep-dive-inside-of-androids-viewmodel-architecture-components-e6756dc0bb11

When is the viewmodel onCleared called

I have just started using android development and trying to use Room library. Since yesterday I am facing this warning message

&gt; w: [kapt] Incremental annotation processing requested, but support is
&gt; disabled because the following processors are not incremental:
&gt; androidx.lifecycle.LifecycleProcessor (NON_INCREMENTAL),
&gt; androidx.room.RoomProcessor (NON_INCREMENTAL).

I have tried to research and fix but unable to avoid this error here is my grale.build file. please suggest/advice what I am doing wrong.

    apply plugin: &#39;com.android.application&#39;
    
    apply plugin: &#39;kotlin-android&#39;
    
    apply plugin: &#39;kotlin-android-extensions&#39;
    
    apply plugin: &#39;kotlin-kapt&#39;
    
    android {
        compileSdkVersion 29
        buildToolsVersion &quot;29.0.2&quot;
        defaultConfig {
            applicationId &quot;ps.room.bookkeeper&quot;
            minSdkVersion 15
            targetSdkVersion 29
            versionCode 1
            versionName &quot;1.0&quot;
            testInstrumentationRunner &quot;androidx.test.runner.AndroidJUnitRunner&quot;
            javaCompileOptions {
                annotationProcessorOptions {
                    arguments = [&quot;room.schemaLocation&quot;:&quot;$projectDir/schemas&quot;.toString()]
                }
            }    
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile(&#39;proguard-android-optimize.txt&#39;), &#39;proguard-rules.pro&#39;
            }
        }
    }
    
    dependencies {
        implementation fileTree(dir: &#39;libs&#39;, include: [&#39;*.jar&#39;])
        implementation &quot;org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version&quot;
        implementation &#39;androidx.appcompat:appcompat:1.0.2&#39;
        implementation &#39;androidx.core:core-ktx:1.0.2&#39;
        implementation &#39;androidx.constraintlayout:constraintlayout:1.1.3&#39;
        implementation &#39;com.google.android.material:material:1.0.0&#39;
        testImplementation &#39;junit:junit:4.12&#39;
        androidTestImplementation &#39;androidx.test:runner:1.2.0&#39;
        androidTestImplementation &#39;androidx.test.espresso:espresso-core:3.2.0&#39;
    
        // life cycle dependencies
        def lifecycle_version = &quot;2.0.0&quot;
        implementation &quot;android.arch.lifecycle:extensions:$lifecycle_version&quot;
        kapt &quot;android.arch.lifecycle:compiler:$lifecycle_version&quot;
    
        //Room dependencies
        //def room_version = &quot;2.1.0&quot;
        implementation &#39;android.arch.persistence.room:runtime:2.1.0&#39;
        kapt &#39;android.arch.persistence.room:compiler:2.1.0&#39;
        //annotationProcessor &#39;android.arch.persistence.room:compiler:2.1.0&#39;
    
    //    implementation &quot;android.arch.lifecycle:extensions:$room_version&quot;
    //    kapt &quot;android.arch.persistence.room:compiler:$room_version&quot;
    //    androidTestImplementation &quot;android.arch.persistence.room:testing:$room_version&quot;
    
        //implementation &#39;androidx.room:room-runtime:2.1.0&#39;
        //annotationProcessor &#39;androidx.room:room-compiler:2.1.0&#39;
    }




Content Type	Original Author	Original Content on Stackoverflow
Question	Cool	View Question on Stackoverflow
Solution 1 - Android	Jorgesys	View Answer on Stackoverflow

What the equivalent of activity life cycle in iOS?

Android Problem Overview

Android Solutions

Solution 1 - Android

threejs how to rotate around object's own center,instead of world center

'require': cannot load such file -- 'nokogiri\nokogiri' (LoadError) when running `rails server`

Attributions