ClassCastException ArrayList Cannot be cast to package.name.ClassNAME can some one Help to fix?

**MelkWeg** · February 6th, 2019, 07:01 PM

hello guys im working on Books Library Sprint .
trying to filter by ISBN number but then when im running Junit Test the Result : ArrayList Cannot be cast to library.PickPeriod(Package Name)

would be greatfull to have some help please !
i know there is something missing after or before the filter..

	public BooksReturnCode pickBook(long isbn, int readerId, LocalDate pickDate) {
		Book book = getBookItem(isbn);
		Reader reader = getReader(readerId);
		if(book == null) return BooksReturnCode.NO_BOOK_ITEM;
		if(!readers.containsKey(readerId)) return BooksReturnCode.NO_READER;
			if(book.getAmount()==book.getAmountInUse())
			return BooksReturnCode.NO_BOOK_EXEMPLARS;
 
		List<PickRecord> pickRecords = readerRecord.getOrDefault(readerId, new ArrayList<>());
		PickRecord record = (PickRecord) pickRecords.stream()
				.filter(d->d.getIsbn()==isbn)
				.collect(Collectors.toList());
 
		if(record!=null&&record.getReturnDate()==null)
			return BooksReturnCode.READER_READS_IT;
 
 
		record = new PickRecord(isbn, readerId, pickDate);
 
		addBookRecord(record);
		addReaderRecord(record);
		addRecords(record);
 
 
		return BooksReturnCode.OK;
	}

**Norm** · February 6th, 2019, 07:18 PM

ArrayList Cannot be cast to library.PickPeriod(Package Name)

An object of type ArrayList can not be cast to the type mentioned in the error message.

What statement was flagged as causing that exception?

**MelkWeg** · February 6th, 2019, 07:30 PM

Originally Posted by Norm

An object of type ArrayList can not be cast to the type mentioned in the error message.

What statement was flagged as causing that exception?

the Casting (PickPeriod) before the start of the stream...
i know for sure the problem is in the Syntax of :

List<PickRecord> pickRecords = readerRecord.getOrDefault(readerId, new ArrayList<>());
PickRecord record = pickRecords.stream()
.filter(d->d.getIsbn()==isbn)
.collect(Collectors.toList());

when im trying to filter , its just making a ERROR in Syntax. and all the code blowing in Red.

**jim829** · February 6th, 2019, 08:02 PM

I don't see a PickPeriod anywhere in there.

Regards,
Jim

**MelkWeg** · February 6th, 2019, 08:32 PM

Originally Posted by jim829

I don't see a PickPeriod anywhere in there.

Regards,
Jim

Sorry its PickRecord which is a Class , i edit the code. can take a look now , in my opinion i just missing something with the Filtering.. i can explain what i should get but the Sprint got alot of Class will be hard to explain with Out seeing the Whole class , i just curios if there is a alternative way for me to search if not with Filter.. Btw if you really up to Help can send you PM

ty for answers Guys!

**Norm** · February 6th, 2019, 08:36 PM

Can you make a small, complete program that compiles and executes to show the problem?
Do not post the whole of your project. Post just a small program for testing.

Sorry its PickRecord

Please don't post things that are not from the program. Post only text from the javac or java programs.
Don't make up error message texts.

  PickRecord record = (PickRecord) pickRecords.stream()
				.filter(d->d.getIsbn()==isbn)
				.collect(Collectors.toList());

What value does the collect method return?
What is the data type to the left of the =?
They need to match.

**MelkWeg** · February 6th, 2019, 08:40 PM

Originally Posted by Norm

Can you make a small, complete program that compiles and executes to show the problem?
Do not post the whole of your project. Post just a small program for testing.

it will be a Problem i dont really have idea how to because all of the Setters/getters etc.. i can post link to mine Project .. and tell you exactly which Class/Lines not working ..if its ok let me know please when youll see whole Class of the Methods youll undrstood what i supposed to do .. i can even Show the UML if its helps . everything which will help to pass mine last JUnit test :\

**Norm** · February 6th, 2019, 08:42 PM

  PickRecord record = (PickRecord) pickRecords.stream()
				.filter(d->d.getIsbn()==isbn)
				.collect(Collectors.toList());

What value/data type does the collect method return?
What is the data type to the left of the =?
They need to match.

**MelkWeg** · February 6th, 2019, 09:02 PM

Originally Posted by Norm

  PickRecord record = (PickRecord) pickRecords.stream()
				.filter(d->d.getIsbn()==isbn)
				.collect(Collectors.toList());

What value/data type does the collect method return?
What is the data type to the left of the =?
They need to match.

d.getIsbn() should be match to the isbn of the Method Parm methodName(long isbn..) . if im getting you right , im kind of new with Streams..
im tryin to return if there is a Reader who reads the book , so no one else could "pick" the Book till the reader will Return it to Library .

Edit : to be more Clearly , i have made List of Records . for readers , so im tryin with that record of Readers to check if some of the Readers Already Reading the BOOK .

**Norm** · February 6th, 2019, 09:14 PM

Look at the API doc for collect. What data type does it return?

**MelkWeg** · February 6th, 2019, 09:20 PM

Originally Posted by Norm

Look at the API doc for collect. What data type does it return?

oh , it will sound Stupid but im sorry i barely get you.. if you think there is a better way to change the method you can give me a Hint ill try to .. , i still think with out seeing mine Project you wouldnt know how to help .. or you can guess cause you seems like a good programer ..

**Norm** · February 6th, 2019, 09:30 PM

All methods are defined as void or as a datatype that they return. What is the definition for the collect method? What does it return?
When assigning the value returned by a method, the datatypes must match.
Datatype var = someMethod();
The someMethod method must be defined to return a value of Datatype.

To see what is being returned, remove the cast and assign the returned value to a variable of type Object. Then print out the class of that variable:

Object obj = .... collect...
System.out.println(obj.getClass());  // show obj's class

I'm done for today. Back tomorrow.

**MelkWeg** · February 6th, 2019, 09:54 PM

Originally Posted by Norm

All methods are defined as void or as a datatype that they return. What is the definition for the collect method? What does it return?
When assigning the value returned by a method, the datatypes must match.
Datatype var = someMethod();
The someMethod method must be defined to return a value of Datatype.

To see what is being returned, remove the cast and assign the returned value to a variable of type Object. Then print out the class of that variable:

Object obj = .... collect...
System.out.println(obj.getClass());  // show obj's class

I'm done for today. Back tomorrow.

java.util.ArrayList .
it is kind what im tryin to return , if there is a Reader who reads it i wanna return Enum COnstant. if there is No Reader who reads it i wanna return Empty ArrayList to avoid Null .
ty for your answering ill be glad to get help tomorrow to find way to fix it

! have a nice day/night

**Norm** · February 7th, 2019, 06:40 AM

java.util.ArrayList .

Ok there is an ArrayList returned. The assignment statement needs to save that to a List variable.
What value do you want from that (possibly empty) list?

**MelkWeg** · February 7th, 2019, 11:06 AM

Originally Posted by Norm

Ok there is an ArrayList returned. The assignment statement needs to save that to a List variable.
What value do you want from that (possibly empty) list?

i have change my Code , JUnit test Passed . but now its not seems like professional Code because there is
yellow color when im running the Coverage.

List<PickRecord> pickRecords =
readerRecord.getOrDefault(readerId, new ArrayList<>());

//1 of 2 branchess missed// if(pickRecords!=null)
//1 of 6 branchess missed// if(pickRecords.stream().anyMatch(p->p.getIsbn()==isbn && p.getReturnDate()==null))
return BooksReturnCode.READER_READS_IT;

can i have your opinion? thank you again .

**Norm** · February 7th, 2019, 11:14 AM

there is yellow color

Sorry, I do not understand what your problem is now.

Is there any message when you move the cursor over the color?

**MelkWeg** · February 7th, 2019, 11:23 AM

Originally Posted by Norm

Sorry, I do not understand what your problem is now.

Is there any message when you move the cursor over the color?

when you running Coverage there is Green Color on the Code.
that means its 100% ok , if there is yellow color it means there is some thing missed as i mentioned
in the Quote i write near to the if statement.
there is missed Branches have no idea what that means to be honest..

and of course if the code got breaking points so it will be Red Color . that means the Test not Passed.

**Norm** · February 7th, 2019, 12:01 PM

there is missed Branches

Sorry, I do not know what is meant by a Branch.

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