FX

How-To's > How do I use binding?

Use the bind keyword to create a relationship between a target variable and a bound expression. The bound expression can be a value of some basic type, an object, the outcome of a function, or the outcome of an expression.

Example Code

The following basic code creates a binding relationship between two variables:

var x = 0;  
def y = bind x;

The following code fragment shows a binding relationship between a variable and the outcome of a conditional expression:

Text {
    translateX: 8
    translateY: 20
    content: bind if (replayTimeline.running) then " Stop" else "Replay"
} 

The following code fragment shows a binding relationship between a variable and the outcome of a function:

enabled: bind enableNextButton( 
    products, 
    pageIndex, 
    productInfoView.product.index, 
    productInfoView.visible)

Tips

• Note that variable y in the first code fragment is declared with the def keyword. This way, no code can directly assign a value to this variable, although its value can be changed by the bind operator. Using the def keyword to define variables improves performance slightly and should be preferred when it can be used.

Examples

• Building GUI Applications With JavaFX, Lesson 5: Applying Data Binding to UI Objects
  This tutorial provides a simple example and description of binding.
• Learning the JavaFX Script Programming Language, Lesson 8: Data Binding and Triggers
  This tutorial describes the syntax of binding in the JavaFX Script programming language.
• Playing Video on the Sides of a Rotating Cube
  The sample shows various instances of data binding. Check out its code to see data binding between two variables, a variable and the outcome of an expression, and a variable and a sequence.
• Shopping Service
  This sample accesses Yahoo's shopping API from JavaFX and demonstrates data binding between a variable and the outcome of a function.

Last Updated: November 2009
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