Java boolean and null strangeness -


could please helpe me in understanding why code generate following output?

please note, f here debug purpose, f[0]=(lastline!=null) equivalent lastline!=null test, not bug.

boolean f[] = new boolean[6]; if (f[0]=(lastline!=null) // есть следующая строка     || (f[1]=isedgetime) // конец сессии      || (f[2]=td.gethour() <10) // или уже утро, после полуночи все свечки хороши     || (f[3]=(td.gethour() == 23 && td.getminute() >=50))     || (f[4]=currserverhour > linehour) // или час сменился     || (f[5]=currserverminutesperiod > linesminutesperiod) ){     answer.append(classcode).append(".")           .append(tickerutils.getroot(ticker))           .append(";").append(minutes).append(";")           .append(line)           .append("\n");     system.out.println(arrays.tostring(f));     if (f[0])         system.out.printf("\"%s\" : %d, currserverminute=%d; %d > %d\n", lastline, (lastline!=null? 1: 0), currserverminute, currserverminutesperiod, linesminutesperiod);     line = lastline; }

output:

[true, false, false, false, false, true] "null" : 0, currserverminute=50; 10 > 9

that can't understand why "lastline" not null, f[0] true , @ same time lastline != null gives me false, null, actually, how be?

if looks assigning f[0] following :

(lastline!=null) // есть следующая строка || (f[1]=isedgetime) // конец сессии  || (f[2]=td.gethour() <10) // или уже утро, после полуночи все свечки хороши || (f[3]=(td.gethour() == 23 && td.getminute() >=50)) || (f[4]=currserverhour > linehour) // или час сменился || (f[5]=currserverminutesperiod > linesminutesperiod)

therefore f[0] can true though lastline null.

try change condition to:

if ((f[0]=(lastline!=null)) // есть следующая строка     || (f[1]=isedgetime) // конец сессии      || (f[2]=td.gethour() <10) // или уже утро, после полуночи все свечки хороши     || (f[3]=(td.gethour() == 23 && td.getminute() >=50))     || (f[4]=currserverhour > linehour) // или час сменился     || (f[5]=currserverminutesperiod > linesminutesperiod) )

if want f[0] contain value of (lastline!=null).

this take care of value of f[0]. however, if f[i] true i, f[i+1] won't evaluated due short circuit evaluation of || condition, you'll have @ 1 true value in f array. i'm not sure if that's want.


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