java - Why does a non-empty List throw a Null Pointer Exception? -


i have list array 'details'. 

list<historydetails> details

where historydetails object containing strings.

when check size gives me positive value.

details.size()

but when try access element throws null pointer exception.

details.get(0).getfirstelement();   attempt invoke virtual method 'java.lang.string com.historydetails.getfirstelement()' on null object reference

i invoking element @ next line check size. hence, nothing should reset. wrong?

a list details having many items can have first item null object. before using item check null.

if(details.get(0)!=null){ details.get(0).getfirstelement(); }

-

Comments

Post a Comment

Popular posts from this blog

OpenCV OpenCL: Convert Mat to Bitmap in JNI Layer for Android -

there several posts converting mat bitmap using utils.mattobitmap() function. i'm assuming function can called in java layer after importing utils class. i want transfer data memory address pointed uint32_t* bmpcontent; in code below. jniexport void jnicall java_com_nod_nodcv_nodcvactivity_runfilter( jnienv *env, jclass clazz, jobject outbmp, jbytearray indata, jint width, jint height, jint choice, jint filter) { int outsz = width*height; int insz = outsz + outsz/2; androidbitmapinfo bmpinfo; if (androidbitmap_getinfo(env, outbmp, &bmpinfo) < 0) { throwjavaexception(env,"gaussianblur","error retrieving bitmap meta data"); return; } if (bmpinfo.format != android_bitmap_format_rgba_8888) { throwjavaexception(env,"gaussianblur","expecting rgba_8888 format"); return; } uint32_t* bmpcontent; if (androidbitmap_lockpixels(env, outbmp,(void**)&bmpcontent)
Read more

python - How to remove the Xframe Options header in django? -

i have made page has iframe . inside iframe want show multiple different links article facebook, or news, or youtube video or other possible url. but, due xframe header, unable so. referred following link: https://docs.djangoproject.com/en/1.8/ref/clickjacking/ , django xframeoptionsmiddleware (x-frame-options) - allow iframe client ip but didn't help. my settings.py file's middleware_classes is: middleware_classes = ( 'django.contrib.sessions.middleware.sessionmiddleware', 'django.middleware.common.commonmiddleware', 'django.middleware.csrf.csrfviewmiddleware', 'django.contrib.auth.middleware.authenticationmiddleware', 'django.contrib.auth.middleware.sessionauthenticationmiddleware', 'django.contrib.messages.middleware.messagemiddleware', 'django.middleware.clickjacking.xframeoptionsmiddleware', ) from http://django-secure.readthedocs.org/en/latest/middleware.html , found using
Read more

android - org.xmlpull.v1.XmlPullParserException: expected: START_TAG {http://schemas.xmlsoap.org/soap/envelope/}Envelope -

i trying hit soap api in application login purpose , getting above mentioned error , can 1 tell me going wrong , first time soap apis. here code hit soap :- vector<object> args = new vector<object>(); hashtable<string, object> hashtable = new hashtable<string, object>(); hashtable.put("email", "mss.siddhart28@gmail.com"); hashtable.put("password", "siddharth"); args.add(hashtable); soapserializationenvelope envelope = new soapserializationenvelope( soapenvelope.ver11); envelope.dotnet = true; envelope.xsd = soapserializationenvelope.xsd; envelope.enc = soapserializationenvelope.enc; (new marshalhashtable()).register(envelope); httptransportse androidhttptransport = new httptransportse( "http://tempuri.org/", 15000); androidhttptransport.debug = true; string result = ""; try { soapobject request = new soapobject("http:
Read more