Java - If statement in foreach not called -


i trying check if string in collection of strings. (the strings in case topics activemq broker) iterate through topic list , compare topics searched 1 (save in variable "compare"). "topic.gettopicname()" definately returns string not why varaible count not set 1 eventhough condition true in 1 case. statement in if clause never executed. overlooking something?

 public arraylist<string> gettopics() throws remoteexception {                try {                   // topics strings broker                  activemqconnectionfactory connectionfactory = new activemqconnectionfactory("tcp://localhost:61616");                 activemqconnection connection;                 connection = (activemqconnection) connectionfactory.createconnection();                 connection.start();                 destinationsource ds = connection.getdestinationsource();                  set<activemqtopic>  topics = ds.gettopics();                 string compare = "physical";                 int count = 0;                   for(activemqtopic topic : topics){                           system.out.println(topic.gettopicname());                         if(compare == topic.gettopicname()) {                              system.out.println("found " + topic.gettopicname());                             count = count + 1;                           }                  }                      if(count == 0){                           system.out.println("no topic found");                      }                      else    system.out.println("topic found");                    } catch (jmsexception e) {                 // todo auto-generated catch block                 e.printstacktrace();             }                    return null;   }

i can't debug code because i'm not sure in activemqconnectionfactory can provide advice.

try adding 

if(compare == topic.gettopicname()) {                          system.out.println("found " + topic.gettopicname());                         count = count + 1;                       }                     else {                         system.out.println("not found " + topic.gettopicname());                     }

the following else statement can see happens when should equal. additionally, think should comparing string using .equals() not == since strings objects.

you can see string comparison using == fail in following code

public static void main(string[] args) {         string compare = "physical";         string somestring = new string("physical");         string[] words = {"test", "cheese", "physical", somestring};          (string s: words) {             if(s == compare) {                 system.out.println(s + " == " + compare);             }             else {                 system.out.println(s + " " + "!= " + compare);             }         }         system.out.println("--------------------------------------------------------");         (string s: words) {             if(s.equals(compare)) {                 system.out.println(s + " == " + compare);             }             else {                 system.out.println(s + " " + "!= " + compare);             }         }     }

prints 

test != physical cheese != physical physical == physical physical != physical -------------------------------------------------------- test != physical cheese != physical physical == physical physical == physical

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