小编use*_*832的帖子

在我的应用程序中,我有一个主要活动和几个片段.当用户单击后退按钮时,片段逐个弹出.我想确定当前在后栈中的哪个片段.因此用于通过片段标签名称识别片段.我使用下面的代码段来获取片段标记名称,但它总是返回null值.

FragmentManager fm = MainActivity.this.getSupportFragmentManager();
String fragmentTag = fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 1).getName();

请帮忙.

编辑,

用标签替换片段,

FragmentManager fm = MainActivity.this.getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.activity_main_content_fragment, fragment, text);

我有一个数组列表和一个单独的字符串.我想将它们转换为JSON格式,并期望它低于json格式.

预期格式,

{  
"last_sync_date": "2014-06-30 04:47:45",
"recordset": [
    {
        "contact_group": {
            "guid": "y37845y8y",
            "name": "Family",        
            "description": "Family members",              
            "isDeleted": 0        
        } 
    },
    {
        "contact_group": { 
            "guid": "gt45tergh4",        
            "name": "Office",        
            "description": "Office members",              
            "isDeleted": 0        
        } 
    } 
]
} 

我用这种方式,这是错的,

public void createGroupInServer(Activity activity, String lastSyncDateTime, ArrayList<ContactGroup> groups)
        throws JSONException {

    // create json object to contact group
    JSONObject syncDateTime = new JSONObject();
    syncDateTime.putOpt("last_sync_date", lastSyncDateTime);

    JSONArray jsArray = new JSONArray("recordset");

    for (int i=0; i < groups.size(); i++) {
        JSONObject adsJsonObject = …