android and sensor

• Basic Java
• Sensors

Just little notes about Android Development, actually I know little about it.

Basic Java

JNI: Java Native Interface, 属于Java的特性，使得Java与本地其他语言交互；如在Java中调用C++，或者在C++中调用Java.

NDK: Native Development Kit, 是Android的一个工具开发包，快速开发C++的动态库，并自动将共享库和应用打包成APK,即可通过NDK在Android中使用JNI与本地代码C++交互．

Android.mk制定源码编译的配置信息，Application.mk配置编译平台的相关内容;

Sensors

Location: longitude, latitude and altitude

Accelerometer: gravity and linear accelerometer

Gyroscope: measuring rotation speed of the device, mostly required for games like 3D racing

proximity: check whether there is some obstacle in a very close distance to your device.

Orientation: magnetic field force in 3-axis space, z is related to magnetic north pole(0 means the top of your phone points to north pole), x is related to ground(90 means phone is standing vertical), y shows roll(0 means phone is facing to the sky, 180 means the screen is facing the ground).