javascript pdf417 reader <s:SimpleText width="50" text="{num.toString()}" click="num++" /> in Java

Create PDF-417 2d barcode in Java <s:SimpleText width="50" text="{num.toString()}" click="num++" />

You can also use one of the following methods to cast as a String:

num as String; String(num);

In addition to the traditional primitive variables, versions of Flex SDK 3.4 and up bring a new data type called Vector, which we encourage using when you need to create a collection of a data type. The new type is similar to an array but enforces elements to be of the same type. As you can see, you get compile time errors but you can adjust the code and avoid runtime errors.

Note: Vectors are similar to Generics in Java and provide compile time type safety since you can specify the array type and ensure you won t get compile time errors.

You can set the size of the array and other features. The Vector data type increases performance, efficiency, and error checking of data. Here s an example of how to declare a vector:

var vector:Vector.<int> = Vector.<int>([10, 11, 12]);

This example generates an array with three numbers. You can enforce and specify the type of the objects. Using Vectors can help ensure you won t get any compile time errors when using explicit data binding since you won t be able to convert the wrong data type. Explicit data binding is used often in Flex and it allows you to avoid runtime errors by catching errors during compile time.

There are many places that the binding classes are using the try and catch expressions and the exceptions being thrown are silently captured by the application without generating any errors. There are cases that the binding didn t occur as expected so you would like to debug in order to know what went wrong. To know if an event was dispatched, you can use the BindingManager class, which will indicate whether an event was fired, sending a trace message to the console. Create a new MXML application and call it DebuggingBinding.mxml. The following code is the exact code used to explain one-way data binding with the exception of adding the BindingManager class. Once the application fires the creationComplete event, you set the object and property you would like to bind. In your case, yoou want to keep track of changes in the Label text property.

< xml version="1.0" encoding="utf-8" > <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="1024" minHeight="768" creationComplete="creationCompleteHandler(event)"> <fx:Script> <![CDATA[ import mx.events.FlexEvent; [Bindable] public var value:String = "Hello World";

protected function creationCompleteHandler(event:FlexEvent):void { BindingManager.debugBinding("label.text"); } ]]> </fx:Script> <s:layout> <s:VerticalLayout /> </s:layout> <s:TextInput id="textInput" change="{value=textInput.text}" /> <s:Label id="label" text="{value}" /> </s:Application>

As you compile and run the example, you can see the trace statements in the console as you type anything into the input box (see Figure 2-6).

As mentioned before, data binding is tremendously valuable, but there are also disadvantages. Without understanding exactly how data binding works and ensuring it is being used correctly, it can create overhead and memory leaks, which will cause your application to suffer in terms of performance. The overhead can cause an application with thousands of Binding tags to choke for even half a second. The alternative is to use another method such as ChangeWatchers or the BindingUtils class, but these require management to avoid memory leaks and are not as easy as using the [Binding] metadata tag. A large Flex

application needs all the help they can get to get better performance. In our opinion, a half a second delay during initialization is not acceptable. You can create your own binding metadata and customize the features to your requirements while controlling all the code that will be generated. As an example we created [TurboBinding], which is a lightweight open source (available from http://github.com/EladElrom/eladlib) binding class with a speed close to the BindingUtils class, but with the ease of setting your binding as a metadata tag, just as you do with the Binding metadata. Here s an example of using the TurboBinding metadata tag:

[TurboBinding(destination="simpleText.text")]

In addition to performance gain, [TurboBinding] provides additional functionality to help avoid memory leaks. Since you don t need to bind a property anymore, you can set the unwatchCounter property and it will remove the listener and avoid memory leaks. For example, let's say you are making a service call to retrieve customer information but once you receive the information you don t need to bind anymore, you can set the unwatchCounter property to 1 and after the information is retrieved, it will clean up.

[TurboBinding(source="textInputOne.text", destination="textInputTwo.text", unwatchCounter=5)]

In the [TurboBinding] metadata, you can bind two properties together. Add twoWay="true" to add the same two-way data binding as is built into Flex. Note that once you use the twoWay property with unwatchCounter the binding will be removed from both binding instances.

[TurboBinding(source="textInputOne.text", destination="textInputTwo.text", twoWay="true", unwatchCounter=5)] public function callBackFunction(newValue:String):void { trace(newValue); }

As you saw in this example, if you set a method next to the [TurboBinding] metadata, it calls back the method once the change is recognized. This is a useful feature for times when you want to do an additional task after binding. To use the TurboBinding tag, you need to call the setup method, because the code is not generated using the mxmlc as in the [Binding] tag. The following example includes using the unwatchCounter property, which removes the binding after the data changes five times; Simple data binding and two-way binding for two text input is shown in Figure 2-7.