隱式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] } 在學習隱式啓動Activity的時候遇到這個錯誤，用的書是李剛的瘋狂Android講義,書上沒有提到這個問題,經過看文檔發現了答案:

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.)

能接受隱式Intent的Activity必須包含android.intent.category.DEFAULT,但LAUNCHER和MAIN例外，能夠不用加，也能夠加上但沒有這個必要。