Multiple adapter attributes can now have optional expressions.

Bug 22957032

Change-Id: If1b04262009a1edf311d097c65e97b194103906e

1 files changed, 13 insertions, 0 deletions

diff --git a/baseLibrary/src/main/java/android/databinding/BindingAdapter.java b/baseLibrary/src/main/java/android/databinding/BindingAdapter.java
index 09bc4823..7409d023 100644
--- a/baseLibrary/src/main/java/android/databinding/BindingAdapter.java
+++ b/baseLibrary/src/main/java/android/databinding/BindingAdapter.java
@@ -72,4 +72,17 @@ public @interface BindingAdapter {
      * @return The attributes associated with this binding adapter.
      */
     String[] value();
+
+    /**
+     * Whether every attribute must be assigned a binding expression or if some
+     * can be absent. When this is false, the BindingAdapter will be called
+     * when at least one associated attribute has a binding expression. The attributes
+     * for which there was no binding expression (even a normal XML value) will
+     * cause the associated parameter receive the Java default value. Care must be
+     * taken to ensure that a default value is not confused with a valid XML value.
+     *
+     * @return whether or not every attribute must be assigned a binding expression. The default
+     *         value is true.
+     */
+    boolean requireAll() default true;
 }