Context.startActivity无法启动Activit

问题描述

采用Application.startActivity()偶现无法启动Activity的现象。

原因分析

首先查询Context.java中startActivity()方法的描述，部分内容如下：

    /**
     * Launch a new activity.  You will not receive any information about when
     * the activity exits.
     *
     * <p>Note that if this method is being called from outside of an
     * {@link android.app.Activity} Context, then the Intent must include
     * the {@link Intent#FLAG_ACTIVITY_NEW_TASK} launch flag.  This is because,
     * without being started from an existing Activity, there is no existing
     * task in which to place the new activity and thus it needs to be placed
     * in its own separate task.
     *
     * <p>This method throws {@link ActivityNotFoundException}
     * if there was no Activity found to run the given Intent.
     *

从以上描述可以看出，如果调用startActivity()方法的Context不是Activity的话，Intent必须要包含FLAGIntent.FLAG_ACTIVITY_NEW_TASK，原因是因为没有Activity启动Activity时可能不存在Activity栈，所以需要添加Intent属性来创建一个Activity栈。

解决办法

为启动的Intent设置intent.flags即可解决此问题。

intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK