## Android NDK: APP variable defined to unknown applications: hello-jni 在使用android-ndk-r4b用命令make APP=hello-jni编译hello-jni例子的时候，出现了以下错误信息： ~~~ Android NDK: APP variable defined to unknown applications: hello-jni Android NDK: You might want to use one of the following: build/core/main.mk:81: *** Android NDK: Aborting . Stop. ~~~ 在查阅了OVERVIEW.TXT后，才发现r4b中编译的时候是以下步骤： ~~~ 1/ Place your native sources under $PROJECT/jni/... 2/ Write $PROJECT/jni/Android.mk to describe your sources to the NDK build system 3/ Optional: write $PROJECT/jni/Application.mk to describe your project in more details to the build system. You don't need one to get started though, but this allows you to target more than one CPU or override compiler/linker flags (see docs/APPLICATION-MK.TXT for all details). 4/ Build your native code by running "$NDK/ndk-build" from your project directory, or any of its sub-directories. ~~~ 照着做就编译成功了，如图：  > 本文转自： > [http://mp870601.blog.163.com/blog/static/13675745320107824850564/](http://mp870601.blog.163.com/blog/static/13675745320107824850564/) > linc注：在r5b中也是一样，现在ndk的文章从网上一搜都是以前的，所以照着做会出现很多问题。希望大家还是以帮助文档为主。这样就能以不变应万变。