android android-source android-constraintlayout

Error: missing android-support-constraint-layout in AOSP but prebuilts/sdk/current/extras has it

My Android source repo already has two jar files android-support-constraint-layout.jar and android-support-constraint-layout-solver.jar respectively at prebuilts/sdk/current/extras/constraint-layout/libs/ and prebuilts/sdk/current/extras/constraint-layout-solver/. Now, I have an app in packages/app, where I have an app/src/main/Android.mk:

LOCAL_STATIC_ANDROID_LIBRARIES := \
...
android-support-constraint-layout \
android-support-constraint-layout-solver

Still, I get the following error after compiling Android:

error: FirstApp (APPS android-x86) missing android-support-constraint-layout (JAVA_LIBRARIES android-x86)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
error: FirstApp (APPS android-x86) missing android-support-constraint-layout-solver (JAVA_LIBRARIES android-x86)

Except the first, none of the methods in this link works to add constraint-layout in AOSP.

Solution

I added constraint-layout in one of the packages in AOSP for Android-Oreo (v8.1).

Download the constraint-layout (.aar) and constraint-layout-solver (.jar) from maven repository: https://mvnrepository.com/artifact/com.android.support.constraint/constraint-layout/1.0.2, https://mvnrepository.com/artifact/com.android.support.constraint/constraint-layout-solver/1.0.2 Put them in the libs/ folder in the app's home (packages/apps/AnotherFirstApp/).

In Android.mk:

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_PACKAGE_NAME := AnotherFirstApp
LOCAL_MODULE_TAGS := optional
LOCAL_DEX_PREOPT := false

LOCAL_SRC_FILES := $(call all-java-files-under, src)

LOCAL_PROGUARD_FLAG_FILES := ../../../frameworks/support/design/proguard-rules.pro


ifeq ($(TARGET_BUILD_APPS),)
support_library_root_dir := frameworks/support
else
support_library_root_dir := prebuilts/sdk/current/support
endif

LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res \
                      $(support_library_root_dir)/design/res \
              $(support_library_root_dir)/v7/cardview/res \
              $(support_library_root_dir)/v7/recyclerview/res \
                      $(support_library_root_dir)/v7/appcompat/res

LOCAL_AAPT_FLAGS := \
    --auto-add-overlay \
    --extra-packages android.support.design \
    --extra-packages android.support.v7.cardview \
    --extra-packages android.support.constraint \
    --extra-packages android.support.v7.recyclerview \
    --extra-packages android.support.v7.appcompat

LOCAL_STATIC_JAVA_LIBRARIES := \
    android-support-design \
    android-support-v7-recyclerview \
    android-support-v4 \
    android-support-v7-cardview \
    android-support-v7-appcompat \
    constraint-layout-solver \

LOCAL_STATIC_JAVA_AAR_LIBRARIES := \
               constraint-layout

include $(BUILD_PACKAGE)

include $(CLEAR_VARS)

LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES := \
           constraint-layout:libs/constraint-layout-1.0.2.aar \
           constraint-layout-solver:libs/constraint-layout-solver-1.0.2.jar 

include $(BUILD_MULTI_PREBUILT)

include $(call all-makefiles-under,$(LOCAL_PATH))

Now, there's no problem. The app builds and runs fine. There might be one issue because of not adding constraint-solver in a way like shared jar, in case other apps are also trying to use this jar. This needs to be handled by adding this jar in the framework or external.

I got help from the following blogs: