java - Android App - Unable to start activity ComponentInfo -

i created app, should receive data thingspeak channel. first used webview widget, want go further , use thingspeak java api handle data myself.

in mainactivity put in code :

channel channel = new channel(1234,"writekey"); try {     entry entry = channel.getlastchannelentry(); } catch (unirestexception e) {     e.printstacktrace(); } catch (thingspeakexception e) {     e.printstacktrace(); }     out.println("entry"); 

but following error:

java.lang.runtimeexception: unable start activity componentinfo{de.babytemp.babytempapp2/de.babytemp.babytempapp2.mainactivity}: java.lang.illegalargumentexception: unknown pattern character 'x' @ android.app.activitythread.performlaunchactivity(activitythread.java:2325) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2387) @ android.app.activitythread.access$800(activitythread.java:151) @ android.app.activitythread$h.handlemessage(activitythread.java:1303) @ android.os.handler.dispatchmessage(handler.java:102) @ android.os.looper.loop(looper.java:135) @ android.app.activitythread.main(activitythread.java:5254) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:903) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:698)                                               caused by: java.lang.illegalargumentexception: unknown pattern character 'x' @ java.text.simpledateformat.validatepatterncharacter(simpledateformat.java:314) @ java.text.simpledateformat.validatepattern(simpledateformat.java:303) @ java.text.simpledateformat.<init>(simpledateformat.java:356) @ com.google.gson.defaultdatetypeadapter.<init>(defaultdatetypeadapter.java:49) @ com.google.gson.gsonbuilder.addtypeadaptersfordate(gsonbuilder.java:555) @ com.google.gson.gsonbuilder.create(gsonbuilder.java:543) @ de.babytemp.babytempapp2.channel.<init>(channel.java:46) @ de.babytemp.babytempapp2.mainactivity.oncreate(mainactivity.java:41) @ android.app.activity.performcreate(activity.java:5990) @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1106) @ android.app.activitythread.performlaunchactivity(activitythread.java:2278) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2387)  @ android.app.activitythread.access$800(activitythread.java:151)  @ android.app.activitythread$h.handlemessage(activitythread.java:1303)  @ android.os.handler.dispatchmessage(handler.java:102)  @ android.os.looper.loop(looper.java:135)  @ android.app.activitythread.main(activitythread.java:5254)  @ java.lang.reflect.method.invoke(native method)  @ java.lang.reflect.method.invoke(method.java:372)  @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:903)  @ com.android.internal.os.zygoteinit.main(zygoteinit.java:698)  

thanks!

package de.babytemp.babytempapp2;  import com.google.gson.gson; import com.google.gson.gsonbuilder; import com.mashape.unirest.http.httpresponse; import com.mashape.unirest.http.jsonnode; import com.mashape.unirest.http.unirest; import com.mashape.unirest.http.exceptions.unirestexception; import com.mashape.unirest.request.getrequest; import java.util.hashmap;  public class channel {  private string apiurl = "http://api.thingspeak.com"; private static final string apiheader = "xxxxxxxxx"; private final integer channelid; private string readapikey; private string writeapikey; private final boolean ispublic; private final hashmap<string, object> fields = new hashmap<>(); private final gson gson = new gsonbuilder().setdateformat("yyyy-mm-dd't'hh:mm:ss").create();  /**  * constructor public, read-only, thingspeak channel. type of  * channel cannot updated.  *  * @param channelid channel id.  */ public channel(integer channelid) {     this.ispublic = true;     this.channelid = channelid; }  /**  * constructor public, writeable, thingspeak channel.  *  * @param channelid channel id.  * @param writekey api key channel. see  * https://thingspeak.com/channels/<channelid>#apikeys  */ public channel(integer channelid, string writekey) {     this.ispublic = true;     this.channelid = channelid;     this.writeapikey = writekey; }  /**  * constructor private, writeable, thingspeak channel.  *  * @param channelid channel id.  * @param writekey write api key. see  * https://thingspeak.com/channels/<channelid>#apikeys.  * @param readkey read api key. see  * https://thingspeak.com/channels/<channelid>#apikeys.  */ public channel(integer channelid, string writekey, string readkey) {     this.channelid = channelid;     this.readapikey = readkey;     this.writeapikey = writekey;     this.ispublic = false; }  /**  * make requests thingspeak api without additional feed  * parameters.  *  * @param url api url.  * @return json string.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ private string thingrequest(string url) throws unirestexception, thingspeakexception {     getrequest request = unirest.get(url);     if (!this.ispublic) {         request.field("key", this.readapikey);     }     httpresponse<jsonnode> response = request.asjson();     if (response.getcode() != 200) {         throw new thingspeakexception("request failed code " + response.getcode());     }     return response.getbody().tostring(); }  /**  * make requests thingspeak api additional feed parameters.  *  * @param url api url.  * @param options optional feed parameters.  * @return json string.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ private string thingrequest(string url, feedparameters options) throws unirestexception, thingspeakexception {     getrequest request = unirest.get(url);     if (!this.ispublic) {         request.field("key", this.readapikey);     }     request.fields(options.fields);     httpresponse<jsonnode> response = request.asjson();     if (response.getcode() != 200) {         throw new thingspeakexception("request failed code " + response.getcode());     }     return response.getbody().tostring(); }  /**  * use server other thingspeak.com. if hosting own  * thingspeak server, set url of server here.  url of public  * thingspeak server http://api.thingspeak.com  *  * @param url eg. http://localhost, http://thingspeak.local:3000, etc.  */ public void seturl(string url) {     this.apiurl = url; }  /**  * update channel new data.  *  * @param entry new data posted.  * @return id of new entry.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public integer update(entry entry) throws unirestexception, thingspeakexception {     httpresponse<string> response = unirest.post(apiurl + "/update")             .header(apiheader, this.writeapikey)             .header("connection", "close")             .fields(entry.getupdatemap())             .asstring();     if (response.getcode() != 200) {         throw new thingspeakexception("request failed code " + response.getcode());     } else if (response.getbody().equals("0")) {         throw new thingspeakexception("update failed.");     }     return integer.parseint(response.getbody()); }  /**  * channel feed default feed options. not include location or status info. fields  * have been named in channel's settings (via web) returned.  *  * @return feed channel.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getchannelfeed() throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/feed.json";     return gson.fromjson(thingrequest(url), feed.class); }  /**  * channel feed additional feed options. fields have been named in  * channel's settings (via web) returned.  *  * @param options additional feed parameters.  * @return feed channel.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getchannelfeed(feedparameters options) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/feed.json";     return gson.fromjson(thingrequest(url, options), feed.class); }  /**  * last entry in channel default feed options.  * faster alternative getting channel feed , calling  * {@link feed#getchannellastentry()}.  *  * @return entry.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public entry getlastchannelentry() throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/feed/last.json";     return gson.fromjson(thingrequest(url), entry.class); }  /**  * last entry in channel additional feed options.  * faster alternative getting channel feed , calling  * {@link feed#getchannellastentry()}  *  * @param options  * @return entry.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public entry getlastchannelentry(feedparameters options) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/feed/last.json";     return gson.fromjson(thingrequest(url, options), entry.class); }  /**  * field feed default feed options.  *  * @param fieldid field include in field (1-8).  * @return feed.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getfieldfeed(integer fieldid) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/field/" + fieldid + ".json";     return gson.fromjson(thingrequest(url), feed.class); }  /**  * field feed additional feed options.  *  * @param fieldid field include in field (1-8).  * @param options optional parameters control format of feed.  * @return feed.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getfieldfeed(integer fieldid, feedparameters options) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/field/" + fieldid + ".json";     return gson.fromjson(thingrequest(url, options), feed.class); }  /**  * last entry in field feed default feed options.   *  * @param fieldid field return (0-8).  * @return last entry specified field.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public entry getlastfieldentry(integer fieldid) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/field/" + fieldid + "/last.json";     return gson.fromjson(thingrequest(url), entry.class); }  /**  * last entry in field feed additional feed options.       *  * @param fieldid field return (0-8).  * @param options supported options: offset, status, , location.  * @return last entry specified field.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public entry getlastfieldentry(integer fieldid, feedparameters options) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/field/" + fieldid + "/last.json";     return gson.fromjson(thingrequest(url, options), entry.class); }  /**  * channel status updates. uses default feed options.  *  * @return status feed.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getstatusfeed() throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/status.json";     return gson.fromjson(thingrequest(url), feed.class); }  /**  * channel status updates.  *  * @param options {@link feedparameters#offset(java.lang.integer)}  * supported.  * @return status feed.  * @throws unirestexception request cannot made.  * @throws thingspeakexception request invalid.  */ public feed getstatusfeed(feedparameters options) throws unirestexception, thingspeakexception {     string url = apiurl + "/channels/" + this.channelid + "/status.json";     return gson.fromjson(thingrequest(url, options), feed.class); } 

}