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 :
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.
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:
An alternative to Gson you could use Jackson.
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();
}
