public static final class的“id/layout/string”都知道使用的去向了。
1）但attr和drawable却不知用到哪去了？
2）而且，怪异的是，BMI\res\drawable-hdpi BMI\res\drawable-mdpi BMI\res\drawable-ldpi都有一幅同名的png，但对应的id只有一个icon=0x7f020000。
3）如果说，attr是预留的，是不是意味着android的R的资源形式只有“attr/drawable/id/layout/string”五种了？
- XML code
/* AUTO-GENERATED FILE. DO NOT MODIFY. * * This class was automatically generated by the * aapt tool from the resource data it found. It * should not be modified by hand. */package com.demo.android.bmi;public final class R { public static final class attr { } public static final class drawable { public static final int icon=0x7f020000; } public static final class id { public static final int height=0x7f050001; public static final int submit=0x7f050000; public static final int suggest=0x7f050003; public static final int weight=0x7f050002; } public static final class layout { public static final int main=0x7f030000; } public static final class string { public static final int advice_average=0x7f040001; public static final int advice_heavy=0x7f040002; public static final int advice_light=0x7f040000; public static final int app_name=0x7f040003; public static final int bmi_btn=0x7f040006; public static final int bmi_result=0x7f040007; public static final int height=0x7f040004; public static final int weight=0x7f040005; }}------解决方案--------------------
2）肯定是两个不同目录下的同一名字的Drawable的ID是相同的,因为这个两个目录中的文件是不能同时使用的,是系统根据屏幕的分辨率,自动选择使用哪个目录的.