Android Build.VERSION.SDK_INT

Build.VERSioN.SDK_INT   代表的操作系统的版本号 ，谷歌的解释大致翻译如下

当前在此硬件上运行的软件的SDK版本装置。当设备启动时，此值从不更改，但它可能当硬件制造商提供OTA更新时增加。

常用来判断sdk版本如下

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
}

后面的版本号，可以鼠标放到上面 +ctrl 按键就可以看到如下图

从源码里面看到当前有所的sdk 版本号

public static class VERSION_CODES {
        public static final int BASE = 1;
        public static final int BASE_1_1 = 2;
        public static final int CUPCAKE = 3;
        public static final int CUR_DEVELOPMENT = 10000;
        public static final int DONUT = 4;
        public static final int ECLaiR = 5;
        public static final int ECLAIR_0_1 = 6;
        public static final int ECLAIR_MR1 = 7;
        public static final int FROYO = 8;
        public static final int GINGERBREAD = 9;
        public static final int GINGERBREAD_MR1 = 10;
        public static final int HONEYCOMB = 11;
        public static final int HONEYCOMB_MR1 = 12;
        public static final int HONEYCOMB_MR2 = 13;
        public static final int ICE_CREAM_SANDWICH = 14;
        public static final int ICE_CREAM_SANDWICH_MR1 = 15;
        public static final int JELLY_BEAN = 16;
        public static final int JELLY_BEAN_MR1 = 17;
        public static final int JELLY_BEAN_MR2 = 18;
        public static final int KITKAT = 19;
        public static final int KITKAT_WATCH = 20;
        public static final int LOLLIPOP = 21;
        public static final int LOLLIPOP_MR1 = 22;
        public static final int M = 23;
        public static final int N = 24;
        public static final int N_MR1 = 25;
        public static final int O = 26;
        public static final int O_MR1 = 27;
        public static final int P = 28;
        public VERSION_CODES() {
            throw new RuntimeException("Stub!");
        }
    }