Startactivityforresult and Setresult

A few days ago my friend asked me about the interaction between the activity, taking advantage of the time to summarize briefly:

1. Start a new activity (B) from an activity (a)

This is usually used more, directly using intent, in activity (A), as follows:

    New Intent (A.This, B.class);    Intent.putextra ("key", "value");    StartActivity (intent);

Here you can pass eight basic data types (Int,string,long,boolean, etc.), as well as bundles (like the map collection).

The parameters to receive the pass in B are as follows:

    String s = getintent (). Getextras (). getString ("key");

You can also use:

  String s = getintent (). Getextras (). getString ("Key", "");

2. In some cases, while activity (A) starts activity (b), we also want B to return a certain data to a, for example, now there is a list containing the user's personal information in a, click Add user information to start B,

After the completion of B, notify a refresh list, using the following:

Start Acitivty (B): Here we do not use startactivity, but with Startactivityforresult, as follows:

        Public Static Final int requestcode = 1;   // declaring global variables       New Intent (A.This, B.class);       Startactivityforresult (Inten T, Requestcode);

Also re-onactivityresult the method in a:

    /*** Requestcode corresponds to Requestcode in Startactivityforresult * ResultCode returned result status, usually three kinds: correct, error, cancel, this is relatively broad, can be defined by themselves * Data returned is usually in*/@Overrideprotected voidOnactivityresult (intRequestcode,intResultCode, Intent data) {        Super. Onactivityresult (Requestcode, ResultCode, data); if(ResultCode! =RESULT_OK) {            return; }        if(Requestcode = = 1) {String s= Data.getstringextra ("Key"); }    }

In B:

      New Intent ();      Intent.putextra ("key", "value");      Setresult (RESULT_OK, intent); The first parameter corresponds to the ResultCode intent in Onactivityresult  corresponding to the data

Note here: Setresult must be called before finish ().

Startactivityforresult and Setresult