startActivityForResult相关

startActivityForResult(intent, 100);

开启一个Activity，被开启的Activity可以返回数据，只要在被打开的页面处

Intent intent = new Intent();
intent.putExtra("msgId", id);
setResult(0, intent);

intent 就是携带的数据

然后：

data 就是intent 可以获取从另一个页面带回来的数据

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 100 && resultCode == 0) {
        int msgId = data.getIntExtra("msgId", -1);
        for (int i = 0; i < mMsgList.size(); i++) {
            if (mMsgList.get(i).id == msgId) {
                mMsgList.get(i).isread = 1;
            }
        }
        mAdapter.notifyDataSetChanged();
    }
}