我在使用JSON数组时遇到问题，我真的希望有人可以帮助我。
假设我有一个带有JSON数据的课程，我发送了＆＃34;意图putextra＆＃34;另一项活动。
在将其发送到另一个活动之前，如何更改null的值？我做了一些打印来发现空值，它们是不同的，例如：
Monday : null
Tuesday : 08:30 - 18:00
Wednesday : 09:00 - 17:00
**and so on.**
问题是 - ＆gt;我有所有json数据，我将它们解析为对象，但我想在之前＆＃34; intent.putextra＆＃34;并将它们发送到另一个活动找到null并用＆＃34; Closed＆＃34;
替换它们所以它看起来像
Monday : Closed
Tuesday : 08:30 - 18:00
Wednesday : 09:00 - 17:00
修改
public class LocationBased extends ListActivity{
// JSON Node names
private static final String TAG_Location = "location_id";
private static final String TAG_Company = "company_id";
private static final String TAG_NAME = "name";
private static final String TAG_ADDRESS = "address";
private static final String TAG_PLACE = "place";
private static final String TAG_POSTAL = "postal";
private static final String TAG_CITY = "city";
private static final String TAG_MONDAY = "monday";
private static final String TAG_TUESDAY = "tuesday";
private static final String TAG_WEDNESDAY = "wednesday";
private static final String TAG_THURSDAY = "thursday";
private static final String TAG_FRIDAY = "friday";
private static final String TAG_SATURDAY = "saturday";
private static final String TAG_SUNDAY = "sunday";
private static final String TAG_TYPE = "type";
private static final String TAG_LAT = "lat";
private static final String TAG_LNG = "lng";
private static final String TAG_NOCAR = "nocar";
private static final String TAG = "Debug of Project"; //
private String a;
private String b;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
SQLiteDatabase db = openOrCreateDatabase("mydb.db", Context.MODE_PRIVATE, null);
db.execSQL("CREATE TABLE IF NOT EXISTS gps_kordinater (ID INTEGER PRIMARY KEY AUTOINCREMENT, Latitude REAL, Longitude REAL);");
String query = "SELECT Latitude,Longitude FROM gps_kordinater WHERE Id = (SELECT MAX(Id) FROM gps_kordinater)";
Cursor cursor = db.rawQuery(query, null);
if(cursor != null)
{
cursor.moveToFirst();
a = cursor.getString(0);
b = cursor.getString(1);
}
String url = "http://webservice.XXX.XX/webservice/getLocationList.php?lat="+ a +"&lng="+ b +"";
Log.d(TAG, "Leyth URL = Lat : " + a +" Long : " + b);
// now enabled if disabled = ingen support for jb aka 4.0
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
JSONParser jParser = new JSONParser();
JSONArray json = jParser.getJSONFromUrl(url);
try {
for(int i = 0; i < json.length(); i++){
JSONObject c = json.getJSONObject(i);
String location_id = c.getString(TAG_Location);
String company_id = c.getString(TAG_Company);
String name = c.getString(TAG_NAME);
String address = c.getString(TAG_ADDRESS);
String place = c.getString(TAG_PLACE);
String postal = c.getString(TAG_POSTAL);
String city = c.getString(TAG_CITY);
String monday = c.getString(TAG_MONDAY);
String tuesday = c.getString(TAG_TUESDAY);
String wednesday = c.getString(TAG_WEDNESDAY);
String thursday = c.getString(TAG_THURSDAY);
String friday = c.getString(TAG_FRIDAY);
String saturday = c.getString(TAG_SATURDAY);
String sunday = c.getString(TAG_SUNDAY);
String type = c.getString(TAG_TYPE);
String lat = c.getString(TAG_LAT);
String lng = c.getString(TAG_LNG);
String nocar = c.getString(TAG_NOCAR);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_Location, location_id);
map.put(TAG_Company, company_id);
map.put(TAG_NAME, name);
map.put(TAG_ADDRESS, address);
map.put(TAG_PLACE, place);
map.put(TAG_POSTAL, postal);
map.put(TAG_CITY, city);
map.put(TAG_MONDAY, monday);
map.put(TAG_TUESDAY, tuesday);
map.put(TAG_WEDNESDAY, wednesday);
map.put(TAG_THURSDAY, thursday);
map.put(TAG_FRIDAY, friday);
map.put(TAG_SATURDAY, saturday);
map.put(TAG_SUNDAY, sunday);
map.put(TAG_TYPE, type);
map.put(TAG_LAT, lat);
map.put(TAG_LNG, lng);
map.put(TAG_NOCAR, nocar);
// Log.d(TAG, "Leyth Days = Mandag : " + monday +" Onsdag : " + wednesday);
// adding HashList to ArrayList
contactList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(this, contactList,
R.layout.list_item,
new String[] { TAG_LAT, TAG_LNG, TAG_POSTAL }, new int[] {
R.id.name, R.id.email, R.id.mobile });
setListAdapter(adapter);
// selecting single ListView item
ListView lv = getListView();
// Launching new screen on Selecting Single ListItem
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
String cost = ((TextView) view.findViewById(R.id.email)).getText().toString();
String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString();
String mandag = ((TextView) view.findViewById(R.id.mandag)).getText().toString();
String tirsdag = ((TextView) view.findViewById(R.id.tirsdag)).getText().toString();
String onsdag = ((TextView) view.findViewById(R.id.onsdag)).getText().toString();
String torsdag = ((TextView) view.findViewById(R.id.torsdag)).getText().toString();
String fredag = ((TextView) view.findViewById(R.id.fredag)).getText().toString();
String lordag = ((TextView) view.findViewById(R.id.lordag)).getText().toString();
String sondag = ((TextView) view.findViewById(R.id.sondag)).getText().toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(), dk.mitaffald.maps.MainActivity.class);
in.putExtra(TAG_LAT, name);
in.putExtra(TAG_LNG, cost);
in.putExtra(TAG_Company, description);
in.putExtra(TAG_MONDAY, mandag);
in.putExtra(TAG_TUESDAY, tirsdag);
in.putExtra(TAG_WEDNESDAY, onsdag);
in.putExtra(TAG_THURSDAY, torsdag);
in.putExtra(TAG_FRIDAY, fredag);
in.putExtra(TAG_SATURDAY, lordag);
in.putExtra(TAG_SUNDAY, sondag);
startActivity(in);
}
});
}
}
答案 0 :(得分：0)
我过去也遇到过这个问题，但我不知道这是一个很好的解决方案，但它对我有用。希望它对你也有用。
String jsonObject_string ;
try {
if (jsonObject != null) {
// ur stuff when not null
}
} catch (Exception e) {
// TODO: handle exception
// when null it automatic fill value
jsonObject_string = "Closed";
}
答案 1 :(得分：0)
在解析JSON文件/对象之前，为什么不尝试将JSON中的所有null字符串替换为字符串？
可能的其他解决方案可能是循环遍历每个对象，检查它们是否为空。然后将其替换为Closed
编辑：
将JSON对象加载为字符串，然后将所有null替换为Closed，如下所示：
String JSON = JsonObject.toString();
JSON.replace("null", "Closed");
编辑2：
在JSONArray json = jParser.getJSONFromUrl(url);下面添加以下内容：
String s = json.toString(); // converts json object to string
json.replace("null", "Closed"); // replaces null for Closed
JSONArray json = new JSONArray(s); // converts back to json object
答案 2 :(得分：0)
据我所知，您想要用特定字符串替换任何空字符串，请说“已关闭”。
这与JSON没有任何关系，如果这是我的代码，我会在将这些值添加到我的意图之前进行简单的检查。代码看起来像这样：
Intent in = new Intent(getApplicationContext(), dk.mitaffald.maps.MainActivity.class);
in.putExtra(TAG_LAT, name == null ? "Closed" : name);
in.putExtra(TAG_LAT, cost== null ? "Closed" : cost);
in.putExtra(TAG_Company, description == null ? "Closed" : description );
in.putExtra(TAG_MONDAY, mandag == null ? "Closed" : mandag);
....
等等。
name == null？ “封闭”：姓名; 简单地询问name是否为null然后关闭值，否则返回name。
它与：
相同if (name == null){
in.putExtra(TAG_LAT, "Closed");
} else {
in.putExtra(TAG_LAT, name);
}
我希望这就是你要找的东西
答案 3 :(得分：0)
if(c.getString(TAG_MONDAY!=null && c.getString(TAG_MONDAY).length>0 && !(c.getString(TAG_MONDAY).equals("")))
{
String monday=c.getString(TAG_MONDAY);
}
else
{
String monday="Closed";
}