java.lang.ClassCastException: cannot be cast to java.lang.Integer -

-

i wanted create compareto method gives me error. can me ?

     package defaultpackage;      public class huffmanentry implements entry<integer, string> {      private string c;        private integer freq;       public huffmanentry(string c, integer freq){          this.c = c;      this.freq = freq;      }       @override      public int compareto(integer arg0) {     if(getkey()<arg0){         return -1;     }else if(getkey()>arg0){         return 1;     }else{         return 0;        } }        @override       public integer getkey() {       return freq;       }

here's error: 

exception in thread "main" java.lang.classcastexception: defaultpackage.huffmanentry cannot cast java.lang.integer @ defaultpackage.huffmanentry.compareto(huffmanentry.java:1)

there serious problems quality of "evidence" have provided us:

  1. the stacktrace seems exception thrown @ line 1 of huffmanentry.java, , impossible.

  2. the stacktrace seems code attempting cast huffmanentry object integer in compareto, (according source code) cannot happen in method. objects used in method have declared type of integer, , there no explicity typecasts.

  3. the stacktrace shows compareto 1 , method call, , impossible.

(3 impossible things before lunch? nah! don't buy it!)

in short, evidence have shown not real. has been tweaked / mangled, , in ways make impossible interpret.

please provide real (complete , unedited) stacktrace, , source code precisely matches compiled code ran produce stacktrace. compilation errors.

alternatively, provide sscce can run ourselves reproduce facially impossible behaviour / evidence.

looking @ code linked to, think understand general problem ... if not specific one.

basically, mixing generic , non-generic code , (you must be) ignoring resulting compiler warnings unchecked conversions, use of raw types , on. result errors should picked java compile-time type checker not being reported.

for example, in myheap.java, write:

private arraylist<entry> entrylist;

but entry generic interface, meaning arraylist being interpreted arraylist<entry<object, object>> object raw type corresponding unbounded type parameters k , t. there int compareto(k) method in entry interface ... , raw type signature int compareto(object).

now @ 

if (entrylist.get(i*2).compareto(entrylist.get(i*2+1))==-1){

note calling entry.compareto(object) passing entry argument. compiler has said ok .... because thinks using raw types @ point. if had been using generics properly, compiler have realized calling entry<k, v>.compareto(entry<k, v>) generic method signature entry<k, v>.compareto(v) . have been flagged compilation error.

i suspect explains strange exception too. java compiler has added hidden runtime typecasts make sure jvm's core runtime type safety not compromised. seeing exception when 1 of runtime checks fails. , happens because ignored or suppressed compile time checks should have told of programming error.

anyway, bottom line should not ignore compiler warnings misuse of generics, unchecked conversions, etc. @ peril ... , in case, got bitten.


Comments

Post a Comment

Popular posts from this blog

php - Magento - Deleted Base url key -

-
i working on cleaning url: http://mydomain.com/shop/shop/deals i going through settings in configuration tab in admin panel on magento , change secure , unsecure base urls remove first base url "shop" web page read: http://mydomain.com/shop/deals so changed unsecure base urls mydomain.com/shop mydomain.com , secure 12.345.67.89/shop 12.345.67.89. wrong thing do. i cannot reload page or admin console. how access these files through ftp , change correctly there?? when make changes in admin panel changes made in database not in file. have make changes in database. 1.go database , select core_config_data table under table find web/unsecure/base_url , web/secure/base_url . make changes here. don't forget clear cache in var/cache folder
Read more

javascript - Tooltipster plugin not firing jquery function when button or any click even occur -

-
i want use tooltipster plugin click element in body show tooltip , want have close button inside tooltip close it. however use jquery click() function handle won't fired. tried solution in post. worked when tooltip triggered hover event. tooltipster plugin not firing jquery function when link in in tooltip clicked the original solution using hover in jsfiddle trigger: 'hover', instead using click show tooltip trigger: 'click', http://jsfiddle.net/bcqyl/7/ it won't fire click event in jquery block. can captured normal javascript function only. checked should code in tooltipster plugin locked , captured "click()" event inside tips when in click trigger mode. i tried other event onchange event of radio button fired when using code in original solution @evan right. tooltip doesn't exist in dom , can't bind/delegate action (even if go way $(document) after domready). if you're after close button inside of too...
Read more

java - WrongTypeOfReturnValue exception thrown when unit testing using mockito -

-
my test list<person> mylist; @test public void testisvalidperson() { mylist = new arraylist<person>(); mylist.add(new person("tom")); when(persondao.get(person)).thenreturn(mylist); when((persondao.get(person)).isempty()).thenreturn(false);//------exception thrown boolean result = service.isvalid("tom"); assertfalse(result); } method tested: public boolean isvalid(string person){ persondao = new persondao(); person personobj = new person(person); return (persondao.get(person).isempty())?false : true; } exception thrown: org.mockito.exceptions.misusing.wrongtypeofreturnvalue: boolean cannot returned get() get() should return list *** if you're unsure why you're getting above error read on. due nature of syntax above problem might occur because: 1. exception *might* occur in wrongly written multi-threaded tests. please refer mockito faq on limitations of concurrency testing. 2. sp...
Read more