Interview Questions.

Q1. Should Model Locator As A Singleton Class? Can't We Instantiate This Class As Like Normal Class?

You can name as a ordinary elegance due to the fact constructor is public.

Q2. Difference Between Array And Array Collection?

Array Collection is a wrapper magnificence primarily based on Array.

Array Collection includes sorting, filtering features however Array no longer.

Array Collection dispatches the Event while new object is brought, up to date or deleted.

Array Collection routinely refreshes/updates the view each time the exchange occurs in Array Collection.

Q3. How To Add Two Commands To One Single Event Type?

Sequence Command is used to feature more than one commands to one occasion kind.

Q4. Difference Between Data Grid And Advanced Data Grid?

Advance Data Grid permits sort by more than one column when you click in the column header. DataGrid lets in only unmarried column kind.

Styling rows and columns: Use the style characteristic property to specify a feature to use patterns to rows and columns of the controls.

Display Hierarchical and Grouped Data: Use an expandable navigation tree in a column to manipulate the seen rows of the manipulate.

Creating Column Groups: Collect a couple of columns beneath a unmarried column heading.

Using Item Renderers: Span a couple of columns with an item renderer and use more than one item renderers within the equal column.

Q5. What Are The Advantages And Disadvantages Of Using Flex? And Why Flex Wins Over Other Technologies?

Flex may be very mature aspect-based totally development framework that reduces the improvement time and offers excellent consequences. There are lots of blessings: Easy to examine, Flash Player to be had widely, Works certainly nicely with different again-end technology (particularly with java), based on additives so very smooth to debug and attach, additionally has a very good IDE and so forth. The hazards are: applications was once slightly heavy etc. But they all may be treated to a great quantity through following up first-rate-practices and good utility architecture.

Q6. Can We Use Text Input/editable Component As Itemrenderer?

Yes.

Q7. Difference Between Item Renderer And Item Editors?

Both are used for modifying,but item renderer is used for showing visual elements..

Object editor is used for modifying motive. Item editor can bypass data lower back from the specific manage to save it as a new price for object being edited. We can also use item renderer as editor by means of the use of boolean assets renderIsEditor.

Itemrenderer is used to format and display the contents in a components while itemeditor allows us to edit the displayed content material

Q8. What Is Serialization?

Object may be represented as collection of bytes that consists of the object's data as well as statistics.

Trfer of facts from patron to the server like sending the Java gadgets from Java to Flex.

Q9. Tell Me Arguments Of Addeventlistener() Method?

AddEventListener (type: string, listener: function, useCapture: Boolean=fake, priority:int=zero, useWeakReference:Boolean=fake):void

kind: Type of Event(MouseClick, MouseOver)

listener: It’s a function

useCapture(dfault:false): If True: Enable best Capturing Phase

Flase: Enable Targetting and Bubbling Phase.

Priority(int=0): The precedence degree of the listener. The better the wide variety the better the concern. 

UseWeakReference(default =false): whether or not the connection with the listener is strong or vulnerable. A strong reference (default) stopping your listener from being rubbish-accrued, a susceptible reference does now not.

Q10. What Is Preventdefault () Method?

To cancel the default behaviour of the event. The strategies of the Event class may be utilized in occasion listener capabilities to have an effect on the behaviour of the occasion object. Some events have an related default behaviour. For instance, the doubleClick event has an associated default behaviour that highlights the word below the mouse pointer at the time of the event. Your occasion listener can cancel this behaviour by using calling the preventDefault () method.

PreventDefault () method will paintings simplest if Cancellable belongings is authentic, otherwise it’s now not working.

Q11. What Is Css (cascading Style Sheet)?

Cascading Style Sheets (CSS) are utilized in Flex to apply patterns to visible additives at the application show list. CSS is a trendy for encapsulating the code that makes up the design of an Application. Given the power and maturity of CSS, most skilled Web designers/developers try to put in force as plenty of the layout and format houses of a Web site/utility in CSS as possible. The result is a good deal greater manage and versatility over the appearance and feel of the site.

Some capabilities of CSS:

Global: patterns implemented to all of the additives.

Type selector: Applied to specific kind of additives in complete task.

Style Name selector: Applied to handiest one thing with the aid of specifying the Style Name belongings.

Q12. What Are All The Events Dispatched In Item Editor?

Item Edit Beginning, Item Edit Begin, Item Edit End

Q13. Explain About Measure() Method? When This Measure() Method Is Called?

The measure() method units the default aspect size, in pixels, and optionally units the issue's default minimal size.

This method is used for following motives:

To set the additives measuredWidth, measuredHeight, measuredMinWidth and measuredMinHeight.

To set the default width and height values to this aspect.

To degree the kid components widths and Heights. So that we will specify how tons width and top is needed for our element.

Measure technique is referred to as best when you are not specifying both width and height externally on the time of calling this component.

This method may be known as a couple of times with the aid of calling the invalidateSize() technique.

Q14. What Is The Use Of Arraycollection Filter Function?

FilterFunction: Function [read-write] : A feature that the view will use to remove items that do not fit the function criteria.

A filter feature is anticipated to feature (object: Object): Boolean When the go back price is proper if the specified item need to stay within the view. If a clear out is unsupported, flex throws as blunders while gaining access to this belongings. We have to call refresh () method after placing the filter out feature belongings for the view to update.

Q15. Explain Data Binding In Flex?

Data binding is the process by means of which changes in a single movement script item are meditated in every other movement script item. (OR) Data binding robotically copies the value of a assets of a supply object to a property of a vacation spot object whilst the supply property modifications.

Data binding calls for a supply belongings, a destination assets, and a triggering occasion that shows when to copy the information from the source to the destination. An object dispatches the triggering event when the source property adjustments

Adobe Flex presents three ways to specify Data binding:

Curly braces ( ) syntax in mxml and [Bindable] metadata tag

<mx: Binding> tag in MXML

BindingUtils.BindProperty/bindSetter methods in Action Script at runtime.

Q16. Difference Between String And String Buffer?

String is immutable and String Buffer is mutable. String class creates new instance for any technique however String Buffer updates/modifies identical example.

Q17. What Type Of Skinning Is Available In Flex?

Graphical skinning, Programmatic Skinning and Stateful skinning:

Graphical Skins: Images that define the advent of the pores and skin. These photos can JPEG, GIF, or PNG files, or they may be symbols embedded in SWF documents. Typically you use drawing software program which include Adobe Photoshop or Adobe Illustrator to create graphical skins.

Programmatic Skins: Action Script or MXML instructions that outline a pores and skin. To change the appearance of controls that use programmatic skins, you edit an Action Script or MXML document. You can use a single magnificence to outline more than one skins.

Sateful Skins: A kind of programmatic skin that makes use of view states, in which every view state corresponds to a nation of the factor. The definition of the view nation controls the look of the pores and skin. Since you may have a couple of view states in a factor, you can use a single factor to define multiple skins.

Q18. Explain About Cairngorm Architecture?

Cairngorm is an implementation of several layout styles that shape a light-weight architectural framework. Cairngorm follows the precept of setting apart the view and commercial enterprise good judgment that's called the Model-View-Controller sample (MVC).

The Pieces of Cairngorm:

Model Locator

View

Front Controller

Command

Delegate

Service

Model Locator: Stores all of your software’s Value Objects (information) and shared variables, in a single vicinity. Similar to an HTTP Session item, except that its saved patron side in the Flex interface in preference to server aspect inside a center tier application server.

View: One or more Flex additives (button, panel, combination field, Tile, and many others) bundled together as a named unit, certain to information in the Model Locator, and producing custom Cairngorm Events based on person interaction (clicks, rollovers, drag n drop.)

Front Controller: Receives Cairngorm Events and maps them to Cairngorm Commands.

Command: Handles business good judgment, calls Cairngorm Delegates and/or other Commands, and updates the Value Objects and variables saved inside the Model Locator

Delegate: Created with the aid of a Command, they instantiate far flung technique calls (HTTP, Web Services, and so forth) and hand the consequences back to that Command.

Service: Defines the faraway method calls (HTTP, Web Services, and so on) to connect to far flung records shops.

Q19. Explain The Configuration Details Of Blaze Ds?

Add BlazeDS JAR documents and dependent JAR files to the WEB-INF/lib listing from BlazeDS venture.

Add BlazeDS configuration files in the WEB-INF/flex listing from BlazeDS project.

Define Message Broker Servlet and a consultation listener in WEB-INF/internet.Xml from BlazeDS undertaking.

The Blaze DS uses 4 foremost configuration documents specifically: 

Services-config.Xml: The top degree Blaze Ds configuration record, this document normally contains safety constraints, channel definitions and logging settings that each of the offerings can use.

Remoting-config.Xml: The remoting carrier configuration record, which defines remoting provider destinations for working with faraway items.

Proxy-config.Xml : The proxy carrier configuration report which defines proxy service locations for working with webservices and HTTP Service (REST Services)                    

Messaging-config.Xml: The messaging carrier configuration file, which defines messaging service destinations for performing submit subscribe messaging. 

Q20. What Is Method Overriding?

Override a technique of a base magnificence for your ActionScript issue. To override the method, you upload a technique with the same signature in your elegance, and prefix it with the override keyword

Q21. What Are The Collections Classes Available In Flex?

Array Collection, XML List Collection, Grouping Collection.

Q22. What Is Adapter In Blaze Ds?

Java Adapter is used to communicate with Java and JMS adapter is used to talk with JMS. Java adapter class lets in us to invoke techniques on a Java object.

Q23. Explain About Remote Object? What Is End Point In Remote Object?

 Remote Object:  Remote Service routinely serializes and deserializes the statistics between Flex purchaser and your server side language. As a result, you can directly call strategies to your Java/.Net/ColdFusion/PHP and so on… objects. This carrier connects to an AMF (Action Message Format) Gateway. AMF protocol trfers facts in a binary format, so the statistics may be moved throughout the network greater quickly.

Endpoint: This belongings is used to pick out the Java internet venture out of your flex customer assignment.

Ex: http://localhost:8080/JavaTest/messagebroker/amf

http: that is a protocol used to speak with webserver from patron. Http me “Hyper Text Trfer Protocol”

localhost: Host name of the system wherein you've got deployed your Java net assignment.

8080: Port variety of the web server wherein you have got deployed your Java assignment.

JavaTest: Context root of the web software to perceive the web assignment uniquely.

Messagebroker/amf: that is the URL sample of the servlet which we have defined in web.Xml record.

<<protocol>>://<<hostname>>:<<port no>>/<<context root>>/<<URL Pattern>>

Q24. What Is The Difference Between Graphical Skinning And Stateful Skinning?

Sateful Skins: A type of programmatic skin that makes use of view states, in which each view country corresponds to a nation of the issue. The definition of the view state controls the look of the skin. Since you may have more than one view states in a factor, you could use a unmarried component to outline a couple of skins.

Q25. What Is Over Loading? Is Method Over Loading Possible In Flex?

No. Method overloading isn't supported in Action Script3.0.

Q26. What Is Composition?

Making use of the already created magnificence functionality or behaviour by way of instantiating the magnificence and calling the desired techniques.

Q27. How To Display The Check Box In Data Grid Header?

<mx:DataGridColumn headerText="ADD" dataField="add"     itemRenderer="mx.Controls.Button"/>

            <itemrendere>

            </itemRenderer>

Q28. Explain About Component Life Cycle?

A set of techniques the framework calls to instantiate, control and smash components. OR The issue instantiation life cycle describes the sequence of steps that arise while you create a component item from a component magnificence. As a part of the lifestyles cycle, Flex mechanically calls component techniques, dispatches activities, and makes the component visible.

Three Main Phases:

BIRTH:Construction, configuration, attachment, initialization

LIFE :  Invalidation, validation, interplay

DEATH : Detachment, garbage series

override protected feature createChildren():void

                        myLab=new Label();

                        myLab.Text="my label";

                        myLab.SetStyle('coloration',"green");

                        this.AddChild(myLab);

            

override protected function updateDisplayList(unscaledWidth:Number,  unscaledHeight:Number):void 

                        myLab.Circulate(0,0);

                        myLab.SetActualSize(one hundred,a hundred);

            

Q29. Difference Between Sealed Class And Dynamic Class?

Sealed Class:                        

A sealed elegance possesses simplest constant set of homes and methods that had been defined at bring together time. Additional properties and techniques can not be introduced at runtime.                              

This enables strict assemble time checking.

It also improves memory usage. Because it doesn’t require an inner hash table for every item example.

All lessons in Action Script 3.Zero are sealed training via default.                    

 Dynamic Class:

A dynamic elegance defines an item that may be altered at run time by using including or converting the residences and strategies.

It doesn’t permit strict bring together time checking.

It consumes greater reminiscence as it requires an internal hash desk for each item instance.

You can create dynamic training through the usage of the dynamic characteristic when you declare a new elegance.

Q30. What Is Calllater () Method?

The callLater () method queues an operation to be carried out for the next screen refresh, instead of in the present day replace. Without the callLater () approach, you may try to get entry to a property of a issue that isn't always but to be had.

Syn: callLater(approach:Function, args:Array):void

Ex: We have a button click on occasion that hundreds records from a XML record or a webservice. That loading of facts could likely have every other resultHandler with a purpose to look ahead to the loading to finish. And in the meantime your button click handler is probably doing a little other matters …so in these conditions we are able to use callLater.

Q31. What Is The Difference Between Viewstack Vs Viewstate?

Actually ViewStack and ViewState are not related. View states deliver one way to alternate the appearance and sense of a factor in reaction to consumer movement. We can also use navigation box e.G. Acordion, ViewStack, Tab navigator and many others. Choice of selecting navigation container or states depends upon requirement of application.

View stack is part used to show distinct views (normally one-of-a-kind information), one by one. View states are related perspectives of a single set of data. For instance ordinary view and superior view for a photo.

In ViewStack components can't be shared easily among the unique perspectives, they had to be created every time view is changed. For example if we need a search box in every view, then it must be created in each view. States work with tritions. We can observe numerous changes to a equal factor in numerous states. They will appear according to states.

Q32. What Is The Use Of Disableautoupdate Method?

This approach prevents the events that represent changes to the underlying facts from being broadcasted via the view. It additionally prevents collection from being up to date. This approach is beneficial wherein multiple gadgets in series are being edited without delay. By disabling the automobile update the changes are obtained as a batch in place of multiple occasions. Also in a DataGrid this method prevents update to the collection at the same time as a particular object is chosen. When object is not selected the DataGrid controls calls enableAutoUpdate() method.

Q33. Difference Between Swc And Swf File?

SWC report is a library file and SWF file is a runnable report. We will reproduction to Flex Projects libs folder.

 SWC is what you operate while you're searching out a library to bring together into your app. You have get admission to to the training and might import person parts. SWF is much more likely what you're seeking out whilst embedding portraits.

Q34. What Is A Filter Function?

We use this characteristic to limit the facts view within the collection to a subset of source facts item. The function should take a single Object parameter, which corresponds to a group item, and have to return a Boolean cost specifying whether or not to consist of the object inside the view.

Q35. Explain About Blaze Ds And Blaze Ds Services?

BlazeDS presents a hard and fast of services that helps you to join a customer-side application to server-side facts, and pass facts among multiple customers linked to the server. BlazeDS implements actual-time messaging among clients.

Blaze DS offerings:

HTTP Service

Webservice

Remote Object 

            HTTP Service: HTTP Service components to have interaction with JSP’s, Servlets and ASP Pages that are not available as Webservice or remoting services locations.

            <mx:HTTPService id=”myService” url=”http://localhost:8400/middlejava/LoginServlet” result=”resultHandler(event)” fault=faultHandler(event)” method=”Get”/>

            Webservice: Webservice additives permit you to access webservices, which might be software modules with strategies. Webservices methods are normally known as operations. Webservice interfaces are defined with the aid of the use of XML. Flex utility can interact with webservices that outline their interfaces in a Webservices Description Language (WSDL) document, that is available as a URL. WSDL is a standard format for describing the messages that a webservice knows the format of those responses to those messages.

            <mx: WebService id=”Webservice” wsdl=”http://search.Yahoo.Com/searchservice?Wsdl” result=”resultHandler (event)” fault=faultHandler (event)” method=”Get”/>

            Remote Object: Remote object components let us access the strategies of server facet java gadgets, without manually configuring the objects as webservices. We can use far off object components in MXML or ActionScript. We can use RemoteObject components with a trendy by myself BLAZE DS internet software or macromedia ColdFusion MX from Adobe. 

Q36. Advantages Of Adobe Flex?

Complete browser portability: any browser that supports flash participant and that includes almost every browser.

Strong backend connectivity: from its inception, flex has featured remarkable help for famous backend technology which include the java and dot Net.

Streaming: flex offers brilliant guide for streaming binary facts. Heavy allocations that desires to trfer big quantity of information to the end person.

Asynchronous: Asynchronous request/response version. Flex offers complete aid for asynchronous processing of person requests.

SVGs (Scalable Vector Graphics): flex stands out from maximum other RIA-primarily based technologies because it helps vector-based drawing and direct embedding of SVG mark-up documents. SVG based images appearance similarly true at any resolution a given browser helps.

 Security and Rich User Interfaces: Robust protection flex leverages the fairly tested flash participant protection.

RUI, flex benefits from halo skins, gradient fills, vector graphics and different flash player features

Q37. What Is A View Cursor?

A cursor is a function indicator; it factors to a selected item inside the series. We use view cursor to traverse items in a group’s data view and adjust the facts in series.

A view cursor includes following techniques:

The moveNext() and movePrevious() to transport the cursor ahead or backward. Use beforeFirst or afterLast residences to check whether or not we've reached the limits.

The findAny(), findFirst() and findLast() strategies flow the cursor to an item that fits the parameter.

Q38. What Is A Metadata Tag?

These tags offer information to Flex compiler concerning the use of our component. Examples are Bindable, Event, DefaultProperty, Inspectable and many others.

Q39. Explain About Different Types Of Channels Available In Blaze Ds?

 HTTP Channel, AMF Channel, RTMP Channel:

AMF Channel: A simple channel endpoint that trport statistics over HTTP in the binary AMF format in an asynchronous name and reaction version.

HTTP Channel: Provides the sample behaviour the AMF Channel/endpoint, but trport information in AMFX format, that is the textual content primarily based representation of AMF.

RTMP Channel: The RTMP Channel creates a single duplex socket connection to the server and offers the server the nice notification of the participant being close down.

Q40. What Is The Difference Between Target And Current Target?

Target: The item that dispatched the occasion (doesn’t change). Target will now not change.

Current Target: The object who's currently being checked for precise occasion listeners (adjustments). Current goal is hold on change.

Q41. Difference Between Flash And Flex?

Flash is used by the designers. Flex is utilized by the developers. Flash uses simplest Flash Player API however Flex uses each Flash Player API and Flex SDK library additionally. Like datavisualization.Swc, automation.Swc, rpc.Swc.

In flash no coding handiest designing.

In flex you may create huge projects.

Q42. What Is Shared Object? (or) How To Store The Data In Local?

 Shared items characteristic like browser cookies. The SharedObject magnificence to save information at the consumer's local hard disk and phone that information all through the same consultation or in a later session. Applications can get entry to best their very own SharedObject facts and only if they're running at the equal area. The statistics is not despatched to the server and isn't reachable by different Adobe® Flex® applications going for walks on other domains, however may be made handy via programs from the identical domain.

            Public var so : SharedObject = SharedObject.GetLocal("mySO");

            so.Statistics.FName = "Wisdomjobs";

Q43. How To Create Custom Events? Explain The Steps To Create A New Custom Event?

To dispatch a new occasion from your custom component, you need to do the subsequent:

(Optional) Create a subclassfrom the flash.Activities.Eventclass to create an occasion elegance that describes the occasion item. 

(Optional) Use the [Event]metadata tag to make the occasion public in order that the MXML compiler recognizes it. 

Dispatch the event the usage of the dispatchEvent() technique. 

Q44. What Is Stoppropagation() And Stopimmediatepropagation()? (or) Difference Between Stoppropagation And Stopimmediatepropagation()? (or) How To Stop The Event Flow/ Event Phases?

StopPropagation: Prevents processing of any event listeners in nodes next to the modern-day node in the event glide. This technique does now not have an effect on any event listeners in the present day node (current target). 

StopImmediatePropagation: Prevents processing of any occasion listeners within the modern-day node and any subsequent nodes in the event float. This approach takes effect at once and it influences event listeners within the current node.

Q45. What Is Clone() Method?

Clone technique creates reproduction reproduction of the event elegance. This technique is achieved mechanically while the event is redispatched in the event listeners.

Q46. What Is Singleton Class? Explain The Steps To Create A Singleton Class?

The singleton sample is a design sample this is used to limit instantiation of a class to 1 object. If we create the class as a singleton then no way to create more than one example. But, we are able to get that unmarried instance in any wide variety of instructions. So all the lessons will share the identical houses and behaviours of that singleton object.

Steps to create a Singleton class:

Consider the MySingleTon class as a singleton elegance.

            Bundle 

                        public elegance MySingleTon 

                                    // Single Instance of Our MySingleTon

                                    private static var instance:MySingleTon;

                                    //DEFINE YOUR VARIABLES HERE

                                    public feature MySingleTon (enforcer:SingletonEnforcer)

                                    

                                                if (enforcer == null)

                                                

                                                             throw new Error( "You Can Only Have One MySingleTon");

                                    

                                    

                                    // Returns the Single Instance

                                    public static function getInstance() : MySingleTon

                                    

                                      if (example == null)

                                      

                                                                         instance = new MySingleTon ( new SingletonEnforcer );

                                      

                                      go back example;

                                    

                       

                          

            // Utility Class to Deny Access to Constructor

            magnificence SingletonEnforcer 

We ought to create one static variable. It can be known as "instance" and it'll be of type MySingleTon. This can be the variable where we will keep our one example of our elegance.

Then we need to create one constructor. The constructor takes one argument - "enforcer". You will be aware that this "enforcer" has a kind of "SingletonEnforcer" which is described directly after our magnificence. Here is the logic in the back of that:

When you placed a category in an ActionScript record below the principle class, it is best to be had to that class.

If the constructor requires this argument – then best our essential class can create an instance of itself, because we do not have access to the “SingletonEnforcer” class. Only the principle elegance has this access.

 We will now not get admission to our class inside the normal way with the aid of using the “new” declaration because we are able to’t name the constructor. Once we get inner of the constructor, we have some traces that make certain things work as planned. The “if” statement ensures that we had a valid “enforcer” handed in. If there wasn’t it throws an Error pointing out that “You Can Have Only One MySingleTon”.

Q47. Does Exclude Or Exclude Class Really Excludes The Data Or Class?

Exclude(and ExcludeClass) tags certainly have an impact on the set of alternatives which might be available in Flex Builder. They don’t exclude the lessons from linking, that is a general false impression. There are MXML alternatives to say “I need to deal with this symbol as exteranally defined” . Depending on how we bring together our application, generally the instructions which might be included are those that are referenced from the root software or instructions, either without delay or via some different magnificence that is referenced directly or no longer from the basis application or training. The -link-document mxmlc choice is very beneficial in that it tells us

what all is in our swf, and

who relied on each class to purpose it to be blanketed.

Q48. What Is Flex?

Flex is an software framework (sure it is a framework!!) that lets in builders to build rich programs for computer (the use of AIR), web, mobiles and tablets (iOS, android, blackberry and many others). The net programs (SWF Files) run in Flash Player that is to be had in greater than 90% computers the world over. For desktop-primarily based programs AIR is needed. There are two important building blocks for development in Flex: ActionScript (used in particular for Logic part) and MXML (used specially for declaration of tags and additives etc).

Q49. What Are The Differences Between Flex three And Flex 4?

There may be lot of syntactic or different variations among the 2, but most important distinction is: In Flex 4 the architecture of components (maximum of) have got changed. These additives (called Spark the older ones in Flex three are called Halo) have separated the position of developer and fashion designer. Spark components have one principal center component class (written in actionscript) that contains the primary logical component and one Skin elegance that handles all the visual elements. We can say center aspect is skeleton and skin is its visible appearance. For example spark button has one middle Button class and one pores and skin elegance for it.

Q50. What Are The Differences Between four.6/four.Five/four.0 And Flex three.0?

 4.5 and 4.6 are used for growing cell based packages. 4.6 has few new additives.

4.0:

Spark additives were introduced. Component common sense and appearance has been separated. Appearance of the components is laid out in skins.

FXG

FTE (Flash Text Engine)

States modified

Effects changed