java - How to access a String array initialized in one method from another method? -

-

i have simple requirement have string array declare @ class level can use anywhere in class.

 string image_url[];//declared outside of methods  //initailzed image_url[] img_url[] public void showjson(string json)     {         parsejson pj =  new parsejson(json);         pj.parsejson();          image_url= parsejson.img_url; toast.maketext(displaymagazine.this, "image loc"+image_url[1], toast.length_short).show();     }

i want use image_url array in following method as:-

 private arraylist preparedata() {           arraylist android_version = new arraylist<>();          (int = 0; < magazine_version_names.length; i++) {             magazineversion magazineversion = new magazineversion();             magazineversion.setmagazine_version_name(magazine_version_names[i]);             magazineversion.setmagazine_image_url(image_url[i]);             android_version.add(magazineversion);         }         return android_version;     }

when run code app crash's null pointer exception @ line:-

magazineversion.setmagazine_image_url(image_url[i]);

this code parsejson:-

public class parsejson {     public static string[] magversion;     public static string[] img_url;     public static string[] download_url;     public static string[] sample_url;     public static string[] status_dl;     public static string[] status_sm;     public static string[] device_id;      public static final string json_array = "result";     public static final string key_magver = "magversion";     public static final string key_imgurl = "img_url";     public static final string key_downloadurl = "download_url";     public static final string key_sampleurl = "sample_url";     public static final string key_status_dl ="status_dl";     public static final string key_device_id ="device_id";      private jsonarray magazines = null;      private string json;      public parsejson(string json){         this.json = json;     }      public void parsejson(){         jsonobject jsonobject=null;         try {             jsonobject = new jsonobject(json);             magazines = jsonobject.getjsonarray(json_array);              magversion = new string[magazines.length()];             img_url = new string[magazines.length()];             download_url = new string[magazines.length()];             sample_url= new string[magazines.length()];             status_dl= new string[magazines.length()];             device_id= new string[magazines.length()];              for(int i=0;i<magazines.length();i++){                 jsonobject jo = magazines.getjsonobject(i);                 magversion[i] = jo.getstring(key_magver);                 img_url[i] = jo.getstring(key_imgurl);                 download_url[i] = jo.getstring(key_downloadurl);                 sample_url[i] = jo.getstring(key_sampleurl);                 status_dl[i] = jo.getstring(key_status_dl);                 device_id[i] = jo.getstring(key_device_id);             }         } catch (jsonexception e) {             e.printstacktrace();         }     }  }

i new programming or suggestion appreciated.thank you.

you array not initialized think that's why giving null pointer exception. try debug why array null. code snippet below execute scenario. 

public class abc {      string image_url[];      public void abc(){         image_url = new string[] {"10","20","30"};     }             public static void main(string[] args) {          abc = new abc();         a.abc();         system.out.println(a.image_url[0]+" "+a.image_url[1]+" "+a.image_url[2]);     } //output - 10 20 30  }

Comments

Post a Comment

Popular posts from this blog

magento2 - Magento 2 admin grid add filter to collection -

-
i created grid in admin xml ui components. need filter collection via url parameter , dont know how achieve that. tried inject requestinterface collection, filter didnt work. di.xml <virtualtype name="slidelistingdataprovider" type="magento\framework\view\element\uicomponent\dataprovider\dataprovider"> <arguments> <argument name="collection" xsi:type="object" shared="false">xxx\xxx\model\resourcemodel\grid\slide\collection</argument> <argument name="filterpool" xsi:type="object" shared="false">slidelistingfilterpool</argument> <!-- define new object filters --> </arguments> </virtualtype> <virtualtype name="slidelistingfilterpool" type="magento\framework\view\element\uicomponent\dataprovider\filterpool"> <arguments> <argument name="applier...
Read more

Android volley - avoid multiple requests of the same kind to the server? -

-
i using volley upload list of images server. happens within service. once image uploaded remove list. problem arises when internet connection breaks. when internet connection breaks , comes again thinking of adding images yet uploaded request queue. this can result in more 1 copy of same image saved on server request same image might have gone through before getting rseponse. how can address scenario? i'm not quite sure why you're using service schedule requests volley automatically runs it's request in seperate thread. nevertheless can listen both request results, successful , unsuccessful adding listeners. you can remove image list schedule request using volley. if succeeds can carry on desired, if fails can add again list. public static request getimageuploadrequest(final string image) { response.listener<t> responselistener = new response.listener<t>() { @override public void onresponse(t response...
Read more

Combining PHP Registration and Login into one class with multiple functions in one PHP file -

-
i'm trying combine registration, activation , login scripts php website backend script front end developer can pass variables different forms to. my question whether appropriate approach this. don't want have lot of php files different pieces of application developing. far have written following 2 functions login, register , activate user front end developer can call: <?php /** * created phpstorm. * user: karl * date: 26/07/2016 * time: 02:25 */ class users { function register_user($email, $password, $user_name) { $server_name = "localhost"; $u_name = "root"; $db_password = "root"; $db_name = "betamath_graspe"; //email notification variable $from_address="info@slack.com"; //registration form $msg_reg_user='username taken. please choose different username'; $msg_reg_email='email registered'; $msg_reg_active=...
Read more