隐式Intent找不到Activity:android.content.ActivityNotFoundException

Here is what i encountered: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=me.waye.intentdemo.intent.action.WAYE_ACTION cat=[me.waye.intentdemo.intent.category.WAYE_CATEGORY] } 在学习隐式启动Activity的时候遇到这个错误，用的书是李刚的疯狂Android讲义,书上没有提到这个问题,通过看文档发现了答案:

Android treats all implicit intents passed to
startActivity() as if they contained at least one category: "
android.intent.category.DEFAULT" (the
CATEGORY_DEFAULT constant). Therefore, activities that are willing to receive implicit intents must include "
android.intent.category.DEFAULT" in their intent filters. (Filters with "
android.intent.action.MAIN" and "
android.intent.category.LAUNCHER" settings are the exception. They mark activities that begin new tasks and that are represented on the launcher screen. They can include "
android.intent.category.DEFAULT" in the list of categories, but don‘t need to.) See
Using intent matching, later, for more on these filters.)

能接受隐式Intent的Activity必须包含android.intent.category.DEFAULT,但LAUNCHER和MAIN例外，可以不用加，也可以加上但没有这个必要。