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, 55 insertions, 0 deletions

diff --git a/core/java/android/annotation/StringDef.java b/core/java/android/annotation/StringDef.java
new file mode 100644
index 000000000000..6b9dff4ae36f
--- /dev/null
+++ b/core/java/android/annotation/StringDef.java
@@ -0,0 +1,55 @@
+/*
+ * 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.ANNOTATION_TYPE;
+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.CLASS;
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+/**
+ * Denotes that the annotated String element, represents a logical
+ * type and that its value should be one of the explicitly named constants.
+ * <p>
+ * Example:
+ * <pre>{@code
+ *  &#64;Retention(SOURCE)
+ *  &#64;StringDef(&#123;
+ *     POWER_SERVICE,
+ *     WINDOW_SERVICE,
+ *     LAYOUT_INFLATER_SERVICE
+ *  &#125;)
+ *  public &#64;interface ServiceName &#123;&#125;
+ *  public static final String POWER_SERVICE = "power";
+ *  public static final String WINDOW_SERVICE = "window";
+ *  public static final String LAYOUT_INFLATER_SERVICE = "layout_inflater";
+ *  ...
+ *  public abstract Object getSystemService(&#64;ServiceName String name);
+ * }</pre>
+ *
+ * @hide
+ */
+@Retention(CLASS)
+@Target({ANNOTATION_TYPE})
+public @interface StringDef {
+    /** Defines the allowed constants for this element */
+    String[] value() default {};
+}