TeaBeans

TeaBeans is a java beans and properties library. It allows to observe object changes and compute lazy expressions.

Depending on TeaBeans

Add the following to your gradle build file :

repositories {
    maven {
      url 'https://maven.ferenyr.info/artifactory/libs-release
    }
}

dependencies {
   compile 'fr.ourten:teabeans:<version number>'
}

Examples

Property declaration

A property can be declared using this syntax :

Property<Double> property=new Property<>(5.5D);

        Double value=property.getValue(); // 5.5D

        property.setValue(6.5D);

Property listeners

A property emit a couple of events when its value is set.

• ValueInvalidationListener, is fired every time the value is set, even if the new it the same as the previous one.

• ValueChangeListener, is fired every time the value change, only when the new value does not equals the previous. This listener provide the previous and new value.

• ListValueChangeListener, a special listener only used for ListProperty. He is fired every time a value is removed, added or replaced in a ListProperty. This listener provide the previous value (null in case addition) and the new value (null in a removal).

• MapValueChangeListener, a special listener only used for MapProperty. He is fired every time a value is removed, added or replaced in a MapProperty. This listener provide the changed key, the previous value (null in an addition) and the new value (null in a removal).

It is worth noting that when a listener is not needed anymore on a property it should be removed with the according method.

Property binding

A property can be bound to another and have its value automatically updated.

Property<Double> original=new Property<>(5D);
        Property<Double> copy=new Property<>(0D);

        copy.bind(original);

        copy.getValue() // 5D

When a property is bound it can not have its value manually set and an exception will be thrown on attempt.

A second type of binding is the BidirectionnalBinding.

When a property A and a B are bidirectionnaly bound any changes made to A or B will update the value of the other. A property bound by this type of binding remains modifiable by hand.

Property<Double> firstBound=new Property<>(5D);
        Property<Double> secondBound=new Property<>(6D);

        secondBound.bindBidirectionnal(firstBound);

        secondBound.getValue(); // 5D

        secondBound.setValue(10D);

        firstBound.getValue() // 10D

When a BidirectionnalBinding is no longer used it should also be removed.

Expression

Expressions are a subType of Bindings.

They help creating bindings with multiple dependencies and a specific supplied result. The result of the expression is computed upon request and is only refreshed when one dependency has changed.

The BaseExpression class contains several helpers methods to build complex expressions.

Property<Integer> integerProperty = new Property<>(10");

Expression<Integer> multiplyExpression = Expression.transform(integerProperty, result -> result * 10);

multiplyExpression.getValue() // 100

integerProperty.setValue(5);

multiplyExpression.getValue() // 50

ListProperty

A ListProperty is a special subType of BaseProperty. It store an observable list of values.

The List used for storing the values can be supplied in constructor. The getValue() of the ListProperty will return an Immutable List.

While it is strongly discouraged the internal list can be directly modified with the getModifiableValue().

Changing any value without using methods of the ListProperty will not propagate events nor trigger bindings refresh.

SetProperty

A SetProperty is very similar to a ListProperty but its internal collection is a Set.

MapProperty

A MapProperty is a special subType of BaseProperty. It store an observable map of values. It is backed by an internal Map which can be supplied in constructor.