java - Short Circuiting vs Multiple if's -


what differences between this:

if(a && b) {      //code }

and this:

if(a) {      if(b)      {           //code      } }

from know b evaluated in first code block if a true, , second code block same thing.

are there benefits of using 1 on other? code execution time? memory? etc.

they compiled same bytecode. no performance difference.

readability difference. huge generalization, short-circuiting looks better nesting clearer. boils down specific use case. i'd typically short-circuit.

i tried out. here's code:

public class test {      public static void main(string[] args) {         boolean = 1>0;         boolean b = 0>1;          if (a && b)             system.out.println(5);          if (a)             if (b)                 system.out.println(5);     } }

this compiles to:

  0: iconst_1   1: istore_1   2: iconst_0   3: istore_2   4: iload_1   5: ifeq          19   8: iload_2   9: ifeq          19  12: getstatic     #2  15: iconst_5  16: invokevirtual #3  19: iload_1  20: ifeq          34  23: iload_2  24: ifeq          34  27: getstatic     #2  30: iconst_5  31: invokevirtual #3  34: return

note how block repeats twice:

  4: iload_1   5: ifeq          19   8: iload_2   9: ifeq          19  12: getstatic     #2  15: iconst_5  16: invokevirtual #3

same bytecode both times.


-

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

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

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