Advanced-Bindings for JavaFX (8)

advanced-bindings is a collection of useful helpers and custom binding implementations to simplify the development of applications that are heavily based on JavaFX's Properties and Bindings.

New Features?

If you have ideas for new custom bindings that could be added to the library feel free to add an issue.

Links

JavaDoc

## Maven Dependencies

Advanced-Bindings releases are available in the Maven Central Repository. You can use it like this:

Stable release

Gradle:

compile 'eu.lestard:advanced-bindings:0.4.0'

Maven:

<dependency>
    <groupId>eu.lestard</groupId>
    <artifactId>advanced-bindings</artifactId>
    <version>0.4.0</version>
</dependency>

Current Development version (Snapshot)

The development version is published automatically to the Sonatype Snapshot repository.

Gradle

repositories {
    maven {
        url "https://oss.sonatype.org/content/repositories/snapshots/"
    }
}

dependencies {
    compile 'eu.lestard:advanced-bindings:0.5.0-SNAPSHOT'
}

Maven

<dependency>
    <groupId>eu.lestard</groupId>
    <artifactId>advanced-bindings</artifactId>
    <version>0.5.0-SNAPSHOT</version>
</dependency>

Features

MathBindings

eu.lestard.advanced_bindings.api.MathBindings.*

Contains Bindings for all methods of java.lang.Math

Example:

@Test
public void testPow(){

    DoubleProperty a = new SimpleDoubleProperty(3);
    DoubleProperty b = new SimpleDoubleProperty(2);

    final DoubleBinding pow = MathBindings.pow(a, b);

    // 3^2 = 9
    assertThat(pow).hasValue(9.0);

    a.set(5);
    b.set(3);

    // 5^3 = 125
    assertThat(pow).hasValue(125.0);
}

Example: safeDevide A binding to express a division like Bindings.divide with the difference that no ArithmeticException will be thrown when a division by zero happens. Instead a default value of 0 is used (or another value defined by the user).

This can be useful because with the standard divide binding you can run into problems when defining something like this:

IntegerProperty a = new SimpleIntegerProperty();
IntegerProperty b = new SimpleIntegerProperty();

NumberBinding result = Bindings
  .when(b.isEqualTo(0))
  .then(0)
  .otherwise(a.divide(b));

This won't work as expected and will throw an ArithmeticException because the expression a.divide(b) is evaluated independently from the b.isEqualTo(0) condition.

With Advanced-Bindings you can write this instead:

IntegerProperty a = new SimpleIntegerProperty();
IntegerProperty b = new SimpleIntegerProperty();

IntegerBinding result = NumberBindings.divideSafe(a,b);

This won't throw an ArithmenticException even when b has a value of 0. While this is "wrong" from a mathematical point of view it can simplify the development of bindings based applications a lot, for example when b is bound to a Slider that has an initial value of 0.

Example: isNaN

@Test
public void testIsNan(){
    DoubleProperty a = new SimpleDoubleProperty();
    DoubleProperty b = new SimpleDoubleProperty();

    final DoubleBinding quotient = a.divide(b);
    BooleanBinding nan = NumberBindings.isNaN(quotient);


    a.set(2);
    b.set(4);

    assertThat(nan).isFalse();


    a.set(0);
    b.set(0);

    assertThat(nan).isTrue();
}

Example: isInfinite

@Test
public void testIsInfinite(){
    DoubleProperty a = new SimpleDoubleProperty();
    DoubleProperty b = new SimpleDoubleProperty();

    DoubleBinding product =  a.multiply(b);

    BooleanBinding infinite = NumberBindings.isInfinite(product);


    a.set(2);
    b.set(4);

    assertThat(infinite).isFalse();

    b.set(Double.MAX_VALUE);

    assertThat(infinite).isTrue();
}

StringBindings

Example: RegExp

@Test
public void testMatches(){
    StringProperty text = new SimpleStringProperty();

    String pattern = "[0-9]*";  // only numbers are allowed

    BooleanBinding matches = StringBindings.matches(text, pattern);


    text.set("19");

    assertThat(matches).isTrue();


    text.set("no number");

    assertThat(matches).isFalse();
}

CollectionBindings

Example: Sum of all integers in an observable list

@Test
public void testSum(){
    ObservableList<Integer> numbers = FXCollections.observableArrayList();

    NumberBinding sum = CollectionBindings.sum(numbers);


    numbers.addAll(1, 2, 3, 5, 8, 13, 21);

    assertThat(sum).hasValue(53.0);

    numbers.add(34);

    assertThat(sum).hasValue(87.0);
}

SwitchBindings

In JavaFX there are standard methods to create IF-THEN-ELSE bindings. But there is no way to create something like a switch for use cases where there are a lot of cases.

Advanced-Bindings has a builder to create switch like bindings:

IntegerProperty base = new SimpleIntegerProperty();

ObservableValue<String> result = switchBinding(base, String.class)
      .bindCase(1, i -> "one")
      .bindCase(3, i -> "three")
      .bindCase(10, i -> "ten")
      .bindDefault(() -> "nothing")
      .build();

There are two differences to the normal switch statement of Java:

While the standard switch statement has a limitation to numbers, Strings and Enums. Only those types can be used as control variable. There is no such limitation for the Switch binding. Every type that has a properly overwritten equals method can be used.
There is no "fall-through" and therefore no break is needed.