Thinking in Google Doc-不同的Apps之间的交互

1.隐式意图

怎么传值我就不细说了，说些一般人不知道的吧。

1）Verify There is an App to Receive the Intent（判断是否有App响应了意图）

you should always include a
verification step before invoking an intent.

    Caution: If you invoke an intent and there is no app
available on the device that     can handle the intent, your app will crash.（没有应用处理意图，应用就会挂掉。）

因为你不能保证每个手机上都有你需要的应用!

PackageManager packageManager = getPackageManager();List activities = packageManager.queryIntentActivities(intent,        PackageManager.MATCH_DEFAULT_ONLY);boolean isIntentSafe = activities.size() > 0;

If isIntentSafe is true, then at least one app will respond to
the intent. If it is

false, then there aren‘t any apps to handle the intent.

2）