com.tavianator.sangria.listbinder

Class ListBinder<T>

java.lang.Object

com.tavianator.sangria.listbinder.ListBinder<T>

Type Parameters:

T - The type of the list element.

public class ListBinder<T>
extends Object

A multi-binder with guaranteed order.

ListBinder is much like Multibinder, except it provides a guaranteed iteration order, and binds a List instead of a Set. For example:

 ListBinder<String> listBinder = ListBinder.build(binder(), String.class)
         .withDefaultPriority();
 listBinder.addBinding().toInstance("a");
 listBinder.addBinding().toInstance("b");
 

This will create a binding for a List<String>, which contains "a" followed by "b". It also creates a binding for List<Provider<String>> — this may be useful in more advanced cases to allow list elements to be lazily loaded.

To add an annotation to the list binding, simply write this:

 ListBinder<String> listBinder = ListBinder.build(binder(), String.class)
         .annotatedWith(Names.named("name"))
         .withDefaultPriority();
 

and the created binding will be @Named("name") List<String> instead.

For large lists, it may be helpful to split up their specification across different modules. This is accomplished by specifying priorities for the ListBinders when they are created. For example:

 // In some module
 ListBinder<String> listBinder1 = ListBinder.build(binder(), String.class)
         .withPriority(0);
 listBinder1.addBinding().toInstance("a");
 listBinder1.addBinding().toInstance("b");

 // ... some other module
 ListBinder<String> listBinder2 = ListBinder.build(binder(), String.class)
         .withPriority(1);
 listBinder2.addBinding().toInstance("c");
 listBinder2.addBinding().toInstance("d");
 

The generated list will contain "a", "b", "c", "d", in order. This happens because the first ListBinder had a smaller priority, so its entries come first. For more information about the priority system, see Priority.

Since:

1.1

Version:

1.1

Author:

Tavian Barnes (tavianator@tavianator.com)

Method Summary

Modifier and Type	Method and Description
LinkedBindingBuilder<T>	addBinding() Add an entry to the list.
static <T> AnnotatedListBinderBuilder<T>	build(Binder binder, Class<T> type) Start building a ListBinder.
static <T> AnnotatedListBinderBuilder<T>	build(Binder binder, TypeLiteral<T> type) Start building a ListBinder.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

build

public static <T> AnnotatedListBinderBuilder<T> build(Binder binder,
                                                      Class<T> type)

Start building a ListBinder.

Type Parameters:

T - The type of the list element.

Parameters:

binder - The current binder, usually AbstractModule.binder().

type - The type of the list element.

Returns:

A fluent builder.

build

public static <T> AnnotatedListBinderBuilder<T> build(Binder binder,
                                                      TypeLiteral<T> type)

Start building a ListBinder.

Type Parameters:

T - The type of the list element.

Parameters:

binder - The current binder, usually AbstractModule.binder().

type - The type of the list element.

Returns:

A fluent builder.

addBinding

public LinkedBindingBuilder<T> addBinding()

Add an entry to the list.

The entry will be added in order for this ListBinder instance. Between different ListBinders, the order is determined by the ListBinder's Priority.

Returns:

A fluent binding builder.

toString

public String toString()

Overrides:

toString in class Object