building hello-jni sample in Android NDK causes error "Default target help does not exist in this project"

Trying to build hello-jni sample in Android NDK. Followed instructions per http://developer.android.com/sdk/ndk/overview.html#samples to create build .xml,

android update project -p . -s

Trying to run under Eclipse Helios SR2. I get this error:

Description Resource Path 开发者_运维问答 Location Type Default target help does not exist in this project build.xml /HelloJni line 2 Ant Buildfile Problem

in build.xml,

<project name="HelloJni" default="help">

any suggestions appreciated.

Suppose your install paths of sdk and ndk are

~/android-sdk-mac_x86/ and ~/android-ndk-r5c

If you don't use Eclipse and use ant

export PATH=${PATH}:~/android-sdk-mac_x86/tools:~/android-ndk-r5c
cd ~/android-ndk-r5c/samples/hello-jni
ndk-build

Assume target 1 is the project target

android update project -t 1 -p ~/android-ndk-r5c/samples/hello-jni

or simply

android update project -t 1 -p .

Debug build

ant debug

Emulator started or device connected

ant install