Add @NotNull, @Nullable, and @IntDef/@StringDef annotations

This changeset adds some annotations for recording whether a
method return value or method parameter can be null (@Nullable),
can never be null (@NotNull), or must be an integer enum or flag
using one of the given constants.

Change-Id: Ic932592ea3bac781c1df364447c57042461333c5

1 files changed, 41 insertions, 0 deletions

diff --git a/core/java/android/annotation/Nullable.java b/core/java/android/annotation/Nullable.java
new file mode 100644
index 0000000..cdba2f6
--- /dev/null
+++ b/core/java/android/annotation/Nullable.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package android.annotation;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+/**
+ * Denotes that a parameter, field or method return value can be null.
+ * <p>
+ * When decorating a method call parameter, this denotes that the parameter can
+ * legitimately be null and the method will gracefully deal with it. Typically
+ * used on optional parameters.
+ * <p>
+ * When decorating a method, this denotes the method might legitimately return
+ * null.
+ * <p>
+ * This is a marker annotation and it has no specific attributes.
+ */
+@Retention(SOURCE)
+@Target({METHOD, PARAMETER, FIELD})
+public @interface Nullable {
+}