Generate links to Android documentation

build.xml

@@ -83,8 +83,19 @@
     <import file="${sdk.dir}/tools/ant/build.xml" />
 
     <target name="doc" depends="-build-setup, -code-gen">
+        <condition property="missing-docs">
+            <not>
+                <available file="${sdk.dir}/docs/reference" type="dir" />
+            </not>
+        </condition>
+        <if condition="${missing-docs}">
+            <then>
+                <echo>Install "Documentation for Android SDK" from the Android SDK Manager to generate links to SDK documentation.</echo>
+            </then>
+        </if>
         <javadoc
             destdir="doc"
+            link="${sdk.dir}/docs/reference"
             sourcepath="${source.absolute.dir}:${gen.absolute.dir}"
             bootclasspathref="android.target.classpath"
             classpathref="jar.libs.ref"