android开发好的界面点击出现android.content.ActivityNotFoundException 解决方法

当出现的android活动界面因未注册显示如下错误时

android.content.ActivityNotFoundException: Unable to find explicit activity class {com.dt.app/com.dt.app.view.group.HotForumActivity}; have you declared this activity in your AndroidManifest.xml?android.content.Ac