Am new to android. Am creating an android project which parses the JSON data and displays it in a ListView. Am using Eclipse to create the project. I have created a file called userinput.json in the raw folder which is subfolder of res. I have given these JSON data inside the file.
[
{"name":"Company A", "hometown":"NJ"},
{"name":"Company B", "hometown":"PA"},
{"name":"Company C", "hometown":"CT"},
{"name":"Company D", "hometown":"NY"},
{"name":"Company E", "hometown":"NJ"}
]
My requirement is to convert this JSON data declared in the Raw resources into JSON array.
Since I have declared the json data in a file, I have to access it from the resources and hence I use BufferedReader to read the file.
But while trying to convert the StringBuilder object to JSON array, I am returned with null.
This is the code I have written:
BufferedReader jsonReader = new BufferedReader(new InputStreamReader(
this.getResources().openRawResource(R.raw.userinput)));
StringBuilder jsonBuilder = new StringBuilder();
try {
for (String line = null; (line = jsonReader.readLine()) != null;)
{
jsonBuilder.append(line).append("\n");
}
jTokener = new JSONTokener(jsonBuilder.toString());
jsonArray = new JSONArray(jTokener.toString());
}
catch (Exception e)
{
throw new RuntimeException(e);
}
ArrayList<User> newArrayOfUsers = User.JsonData(jsonArray);
In a seperate Java file I have the below two methods to convert my JSON Array into Java Objects:
public User(JSONObject object)
{
try
{
this.name = object.getString(name);
this.hometown = object.getString(hometown);
}
catch(JSONException e)
{
e.printStackTrace();
}
}
public static ArrayList<User> JsonData(JSONArray jsonArray)
{
ArrayList<User> users = new ArrayList<User>();
for(int i = 0; i < jsonArray.length(); i++)
{
try
{
users.add(new User(jsonArray.getJSONObject(i)));
}
catch(JSONException e)
{
e.printStackTrace();
}
}
return users;
}
I am not sure, whether am doing this in correct way, Can anyone please guide me how to get JSON array from the StringBuilder?
this works...
BufferedReader jsonReader = new BufferedReader(new InputStreamReader(
this.getResources().openRawResource(R.raw.userinput)));
StringBuilder jsonBuilder = new StringBuilder();
try {
for (String line = null; (line = jsonReader.readLine()) != null;) {
jsonBuilder.append(line).append("\n");
}
Toast.makeText(this, jsonBuilder.toString(), 1).show();
//JSONTokener jTokener = new JSONTokener(jsonBuilder.toString());
JSONArray jsonArray = new JSONArray(jsonBuilder.toString());
for(int i=0;i<jsonArray.length();i++)
{
JSONObject tmpjsonobject=jsonArray.getJSONObject(i);
Toast.makeText(this, tmpjsonobject.getString("name")+"\n"+tmpjsonobject.getString("hometown"), 1).show();
}
} catch (Exception e) {
throw new RuntimeException(e);
}
and #Salvin is right ...there is no need for JsonTokener .....
You can Java's Scanner class on Android to parse a raw data file and create a JSONArray. Assuming you have a file called my_raw_json.json in your res/raw dir:
Scanner scanner = new Scanner(context.getResources().openRawResource(R.raw.my_raw_json));
String json = scanner.useDelimiter(REGEX_INPUT_BOUNDARY_BEGINNING).next();
JSONArray array = new JSONArray(json);
Related
I want to get a list of JSON objects with JSON from a API. For example affiliate.itunes
but with gson I can't go throw a jsonObject and i have to use java JSONObject and JSONArray class for this mater.
Is it possible to handle this completely with gson lib ?
This is json file that I copied into my android raw folder
and this is my code
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
GsonBuilder builder = new GsonBuilder();
Gson gson = builder.create();
InputStream inputStream = getResources().openRawResource(R.raw.file);
String jsonStr = streamToString(inputStream);
try {
JSONObject jsonObject = new JSONObject(jsonStr);
JSONArray jsonArray = jsonObject.getJSONArray("results");
Type type = new TypeToken<List<BandJsonResult>>(){}.getType();
List<BandJsonResult> jsonResults = gson.fromJson(jsonArray.toString(),type);
for(int i = 0 ; i < jsonResults.size() ; i++){
Log.e("JSON " + i ,jsonResults.get(i).toString());
}
} catch (JSONException e) {
e.printStackTrace();
}
}
private String streamToString(InputStream stream) {
InputStreamReader reader = new InputStreamReader(stream);
BufferedReader bufferedReader = new BufferedReader(reader);
StringBuilder result = new StringBuilder();
String line = "";
try {
while ((line = bufferedReader.readLine()) != null) {
result.append(line);
}
}catch (IOException ex){
ex.printStackTrace();
}
return result.toString();
}
}
Gson uses reflection by default to (de-)serialize classes (unless you provide custom adapters), see also this example in the Gson user guide. Based on the screenshot you could add these two classes:
// You can give these classes any name
class ApiResponse {
// Uses the field names for (de-)serialization by default, but you can also
// specify custom names using #SerializedName
private int resultCount;
private List<BandResult> results;
}
class BandResult {
// You can also use enums and then either name the enum constants the same
// as the values, or annotate the enum constants with #SerializedName
private String wrapperType;
private String kind;
private int artistId;
...
}
And then use them when calling Gson.fromJson:
ApiResponse apiResponse = gson.fromJson(jsonStr, ApiResponse.class);
I want to assign the JSONfile inside the Resources to a instance from JsonObject and parse it.
Please guide how?
MainActivicy:
boolean bool = true;
boolean bool2=true;
String s = "";
input = getResources().openRawResource(R.raw.infojson);
JsonReader reader = new JsonReader(new InputStreamReader(input));
reader.beginObject();
while (bool==true){
String sv ="";
sv=reader.nextName();
s +=sv;
if(sv.equals("id")| sv.equals("num")){
s +=" : " ;
s+=(String.valueOf(reader.nextInt()));
}
if (sv.equals("name")){
s +=" : " ;
s+=reader.nextString();
}
s+="\t";
bool = reader.hasNext();
}
JSON Content:
{
"id":"1","name":"E1","num":1111,
"My":{"id":"2","name":"E2","num":2222}
}
Create a model to parse your json like below:
class ResourseResponse {
private String id;
private String name;
private String num;
//getter-setter
}
Then parse your json from JsonReader and create your model.
JsonReader reader = new JsonReader(new InputStreamReader(input));
Gson gson = new Gson();
if (reader.peek() != JsonToken.BEGIN_OBJECT) {
reader.beginArray();
while (reader.hasNext()) {
ResourseResponse response = gson.fromJson(reader, ResourseResponse.class);
//Add to list
}
reader.endArray();
} else {
ResourseResponse message = gson.fromJson(reader, ResourseResponse.class);
}
If the JSON content is not too big, you can easily create org.json.JSONObject and iterate its keys.
String jsonStr = "{\"id\":\"1\",\"name\":\"E1\",\"num\":1111, \"My\":{\"id\":\"2\",\"name\":\"E2\",\"num\":2222} }"
JSONObject json = new JSONObject(jsonStr);
json.keys().forEachRemaining(x -> {
System.out.println(x.toString());
try {
if (json.get(x.toString()) instanceof JSONObject) {
System.out.println(json.get(x.toString())); / here you can iterate the internal json object
}
} catch (JSONException e) {
e.printStackTrace();
}
});
Output is:
num
name
id
My
{"num":2222,"name":"E2","id":"2"}
Im trying to parse json array data into listview!I searched the whole internet and always was on one point! Json aray must have header something like this
"emp_info":[{"employee name":"Adam","employee no":"101700"},{"employee name":"John","employee no":"101701"},{"employee name":"Paul","employee no":"101702"},{"employee name":"Mark","employee no":"101703"},{"employee name":"Donald","employee no":"101704"},{"employee name":"Brain","employee no":"101705"},{"employee name":"Kevin","employee no":"101706"}]}
Where by my understanding the "emp_info" is the header file by which i must search for rest data inside it in android!My College pretending that i can accept and parse the same data into listview without that header name,but every bit of code where i searched to parse json in android was a single line like this!
JSONObject obj = new JSONObject(jsonString);
JSONArray stations = obj.getJSONArray("emp_inf");
where i just have to put the jsonarray header file as you can see in this piece of code!So please help me is that possible to accept json array without this code?because if i try to remove this code i get nullpointer in my code!Will be very happy if you could at least say yes or no!
Posting Full Codes!
Here is the android class which gets the Json and loads it into List View
private class JsonReadTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://54.148.41.171/server/index/dompy");
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
// e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
#Override
protected void onPostExecute(String result) {
ListDrwaer();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
// passes values for the urls string array
task.execute(new String[] { url });
}
// build hash set for list view
public void ListDrwaer() {
List<Map<String, String>> employeeList = new ArrayList<Map<String, String>>();
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("emp_info");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String name = jsonChildNode.optString("empployee no");
String number = jsonChildNode.optString("etc.");
String outPut = name + "-" + number;
employeeList.add(createEmployee("data", outPut));
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
SimpleAdapter simpleAdapter = new SimpleAdapter(this, employeeList,
android.R.layout.simple_list_item_1,
new String[] { "employee no" }, new int[] { android.R.id.text1 });
listView.setAdapter(simpleAdapter);
}
private HashMap<String, String> createEmployee(String name, String number) {
HashMap<String, String> employeeNameNo = new HashMap<String, String>();
employeeNameNo.put(name, number);
return employeeNameNo;
}
}
And by this json array im successfully able to fetch the json which type is the next!
{"emp_info":[{"employee name":"Adam","employee no":"101700"},{"employee name":"John","employee no":"101701"},{"employee name":"Paul","employee no":"101702"},{"employee name":"Mark","employee no":"101703"},{"employee name":"Donald","employee no":"101704"},{"employee name":"Brain","employee no":"101705"},{"employee name":"Kevin","employee no":"101706"}]}
And here is the json array which my college pretends that i must accept!
{"data":"123"}
And im Saying that its not possible to load this json into list view just because it dont have header file like mine the emp_info,but hes saying its not matter i just MUST accept!We just on same project and i just cant understand is it even possible to do what he says?
String name = jsonChildNode.optString("empployee no");
String number = jsonChildNode.optString("etc.");
How can you get the data by "etc." tag I could not understand it firstly. It should return "" instead of employee number.
I've got a little problem with parsing json into my android app.
This is how my json file looks like:
{
"internalName": "jerry91",
"dataVersion": 0,
"name": "Domin91",
"profileIconId": 578,
"revisionId": 0,
}
As You can see this structure is a little bit weird. I dont know how to read that data in my app. As I noticed those are all Objects not arrays :/
You can always use good old json.org lib. In your Java code :
First read your json file content into String;
Then parse it into JSONObject:
JSONObject myJson = new JSONObject(myJsonString);
// use myJson as needed, for example
String name = myJson.optString("name");
int profileIconId = myJson.optInt("profileIconId");
// etc
UPDATE 2018
After 5 years there is a new "standard" for parsing json on android. It's called moshi and one can consider it GSON 2.0. It's very similar but with design bugs fixed that are the first obstacles when you start using it.
https://github.com/square/moshi
First add it as a mvn dependency like this:
<dependency>
<groupId>com.squareup.moshi</groupId>
<artifactId>moshi-kotlin</artifactId>
<version>1.6.0</version>
</dependency>
After adding it we can use like so (taken from the examples):
String json = ...;
Moshi moshi = new Moshi.Builder().build();
JsonAdapter<BlackjackHand> jsonAdapter = moshi.adapter(BlackjackHand.class);
BlackjackHand blackjackHand = jsonAdapter.fromJson(json);
System.out.println(blackjackHand);
More infos on their GitHub page :)
[old]
I would recommend using Gson.
Here are some links for tutorials:
how to convert java objecto from json format using GSON
Parse JSON file using GSON
Simple GSON example
Converting JSON data to Java object
An alternative to Gson you could use Jackson.
Jackson in 5 minutes
how to convert java object to and from json
This libraries basically parse your JSON to a Java class you specified.
to know if string is JSONArray or JSONObject
JSONArray String is like this
[{
"internalName": "blaaa",
"dataVersion": 0,
"name": "Domin91",
"profileIconId": 578,
"revisionId": 0,
},
{
"internalName": "blooo",
"dataVersion": 0,
"name": "Domin91",
"profileIconId": 578,
"revisionId": 0,
}]
and this String as a JSONOject
{
"internalName": "domin91",
"dataVersion": 0,
"name": "Domin91",
"profileIconId": 578,
"revisionId": 0,
}
but how to call elements from JSONArray and JSONObject ?
JSNOObject info called like this
first fill object with data
JSONObject object = new JSONObject(
"{
\"internalName\": \"domin91\",
\"dataVersion\": 0,
\"name\": \"Domin91\",
\"profileIconId\": 578,
\"revisionId\": 0,
}"
);
now lets call information from object
String myusername = object.getString("internalName");
int dataVersion = object.getInt("dataVersion");
If you want to call information from JSONArray you must know what is the object position number or you have to loop JSONArray to get the information for example
looping array
for ( int i = 0; i < jsonarray.length() ; i++)
{
//this object inside array you can do whatever you want
JSONObject object = jsonarray.getJSONObject(i);
}
if i know the object position inside JSONArray ill call it like this
//0 mean first object inside array
JSONObject object = jsonarray.getJSONObject(0);
This part do in onBackground in AsyncTask
JSONParser jParser = new JSONParser();
JSONObject json = jParser.getJSONFromUrl(url);
try {
result = json.getString("internalName");
data=json.getString("dataVersion");
ect..
} catch (JSONException e) {
e.printStackTrace();
}
JsonParser
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "utf-8"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
I suggest you to use a library like gson as #jmeier wrote on his answer. But if you want to handle json with android's defaults, you can use something like this:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String s = new String("{\"internalName\": \"domin91\",\"dataVersion\": 0,\"name\": \"Domin91\",\"profileIconId\": 578,\"revisionId\": 0,}");
try {
MyObject myObject = new MyObject(s);
Log.d("MY_LOG", myObject.toString());
} catch (JSONException e) {
Log.d("MY_LOG", "ERROR:" + e.getMessage());
}
}
private static class MyObject {
private String internalName;
private int dataVersion;
private String name;
private int profileIconId;
private int revisionId;
public MyObject(String jsonAsString) throws JSONException {
this(new JSONObject(jsonAsString));
}
public MyObject(JSONObject jsonObject) throws JSONException {
this.internalName = (String) jsonObject.get("internalName");
this.dataVersion = (Integer) jsonObject.get("dataVersion");
this.name = (String) jsonObject.get("name");
this.profileIconId = (Integer) jsonObject.get("profileIconId");
this.revisionId = (Integer) jsonObject.get("revisionId");
}
#Override
public String toString() {
return "internalName=" + internalName +
"dataVersion=" + dataVersion +
"name=" + name +
"profileIconId=" + profileIconId +
"revisionId=" + revisionId;
}
}
}
Please checkout ig-json parser or Logan Square for fast and light JSON library.
For comparison, this is the stats from Logan Square developer.
Here you can parse any file from assets folder
fetch file from assets folder
public void loadFromAssets(){
try {
InputStream is = getAssets().open("yourfile.json");
readJsonStream(is);
} catch (IOException e) {
e.printStackTrace();
}
}
Convert JSON to your class object
public void readJsonStream(InputStream in) throws IOException {
Gson gson = new Gson();
JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));
reader.setLenient(true);
int size = in.available();
Log.i("size", size + "");
reader.beginObject();
long starttime=System.currentTimeMillis();
while (reader.hasNext()) {
try {
Yourclass message = gson.fromJson(reader, Yourclass.class);
}
catch (Exception e){
Toast.makeText(this, e.getCause().toString(), Toast.LENGTH_SHORT).show();
}
}
reader.endObject();
long endtime=System.currentTimeMillis();
long diff=endtime-starttime;
int seconds= (int) (diff/1000);
Log.i("elapsed",seconds+"");
reader.close();
}
As the title says. I'd like to just use a JSON. Here is my code for what I'm guessing is my main activity. This grabs all the contents and places them in their respectful variables I'm hoping. Placed at the beginning:
public class WordDetailActivity extends FragmentActivity {
// Reading text file from assets folder
StringBuffer sb = new StringBuffer();
BufferedReader br = null; {
try {
br = new BufferedReader(new InputStreamReader(getAssets().open(
"wordlist.txt")));
String temp;
while ((temp = br.readLine()) != null)
sb.append(temp);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
br.close(); // stop reading
} catch (IOException e) {
e.printStackTrace();
}
}
String myjsonstring = sb.toString();
// Try to parse JSON
try {
// Creating JSONObject from String
JSONObject jsonObjMain = new JSONObject(myjsonstring);
// Creating JSONArray from JSONObject
JSONArray jsonArray = jsonObjMain.getJSONArray("employee");
// JSONArray has four JSONObject
for (int i = 0; i < jsonArray.length(); i++) {
// Creating JSONObject from JSONArray
JSONObject jsonObj = jsonArray.getJSONObject(i);
// Getting data from individual JSONObject
int id = jsonObj.getInt("id");
String word = jsonObj.getString("word");
String dictionary = jsonObj.getString("dictionary");
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}
Now I have another file called WordContent.java that defines these variable again (a non edited version):
public static Map<String, WordItem> ITEM_MAP = new HashMap<String, WordItem>();
static {
// Add 3 sample items.
addItem(new WordItem("1", "This Word", "Blah blah blah"));
}
private static void addItem(WordItem item) {
ITEMS.add(item);
ITEM_MAP.put(item.id, item);
}
/**
* A dummy item representing a piece of content.
*/
public static class WordItem {
public String id;
public String word;
public String dictionary;
public WordItem(String id, String word, String dictionary) {
this.id = id;
this.word = word;
this.dictionary = dictionary;
}
#Override
public String toString() {
return word;
}
}
}
I haven't edited them yet because I have no idea where to go from here. Or rather how to put the contents of my JSON to the WordItem so they show up when I run the program. Another way to look at all of my code that is similar to this is to just create a Master/Detail Flow project in the Eclipse ADT bundle. I hope I'm saying all of this right. Let me know if there are more details I should shed. Very new to Android Dev but any pointer in the right direction is greatly appreciated.
Personally, I would do the JSON parsing in a separate file and probably use an AsyncTask. This is so you can decouple your files/classes as you really do not need an Activity for the parsing.
I tried to reuse as much of your code you posted above. With that being said, something like this should work or put you in the right direction:
public class ParseJsonTask extends AsyncTask<Void, Void, String> {
private Context mCtx;
public ParseJsonTask(Context ctx) {
this.mCtx = ctx;
}
#Override
protected String doInBackground(Void... params) {
// Reading text file from assets folder
StringBuffer sb = new StringBuffer();
BufferedReader br = null;
try {
br = new BufferedReader(new InputStreamReader(mCtx.getAssets().open("wordlist.txt")));
String temp;
while ( (temp = br.readLine()) != null )
sb.append(temp);
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
br.close(); // stop reading
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.tostring();
}
#Override
protected void onPostExecute(Void jsonString) {
WordContent word = new WordContent(); // We use this oject to add the JSON data to WordItem
// Try to parse JSON
try {
// Creating JSONObject from String
JSONObject jsonObjMain = new JSONObject(jsonString);
// Creating JSONArray from JSONObject
JSONArray jsonArray = jsonObjMain.getJSONArray("employee");
// JSONArray has four JSONObject
for (int i = 0; i < jsonArray.length(); i++) {
// Creating JSONObject from JSONArray
JSONObject jsonObj = jsonArray.getJSONObject(i);
// Getting data from individual JSONObject
int id = jsonObj.getInt("id");
String word = jsonObj.getString("word");
String dictionary = jsonObj.getString("dictionary");
// We can use the three variables above...
word.addItem(new WordItem(id, word, dictionary));
// or we can simply do...
// word.addItem(new WordItem(jsonObj.getInt("id"), jsonObj.getString("word"), jsonObj.getString("dictionary")));
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Now whenever you want to parse the JSON file and use the class above you simply do the following:
ParseJsonTask task = new ParseJsonTask(getBaseContext());
task.execute();
Let me know if you have any questions...