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emma roberts

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since May 30, 2018
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Recent posts by emma roberts

i work with eclipse oxygen i write two program one server and other client and i want to execute then with cmd windows i use the version of jdk 1.8 the javac name of program pass successful but when i execute the program with java name of program it generate an error Impossible to found or load the pricipal class someone help me how i solve this problem taking on consideration that i configure the variable path system giving the chemin to directory bin of jdk.
3 weeks ago
i want to create a little chat application like messenger but i have no idea how it's going someone can help me how am i starting
1 month ago
yes i get:
A collection coming up.
60
but i don't undrestand why 'Acollection coming up' is printed once
What will the program print when it is compiled and run?
ithis snippet of code of SCJP book :

select the one correct answer
Select the one correct answer.
(a) A collection coming up.
60
(b) A collection coming up.
A collection coming up.
A collection coming up.
60
(c) The program does not compile.
(d) None of the above.
i compile and execute this code the correct answer is (a) but i don't understand why it print once  A collection coming up.
What will the program print when it is compiled and run?
ithis snippet of code of SCJP book :

select the one correct answer
Select the one correct answer.
(a) A collection coming up.
60
(b) A collection coming up.
A collection coming up.
A collection coming up.
60
(c) The program does not compile.
(d) None of the above.
i compile and execute this code the correct answer is (a) but i don't understand why it print once  A collection coming up.
please i still hava a difficult to undrestand the mean of (c) and (d) and why they are wrong
i have the snippet of code od SCJP book
Which code, when inserted at (1), will provide a correct implementation of the
hashCode() method in the following program?

Select the two correct answers.
(a) return 31337;
(b) return accumulated / count;
(c) return (count << 16) ^ accumulated;
(d) return ~accumulated;
(e) return count == 0 ? 0 : average();
the correct answer is (a) and (e)
(b) is incorrect because of count if it is null it will genearte arithmetic Exception
but i don't now the mean of (c) and (d) and why are false
is this syntax has amean in java

return (count << 16) ^ accumulated;
I want to say that can i override the equals method but i pass as argument a name of class extends of object  instead of object
please why i can't override an equals method with a class how is a subclass of class object?
sorry but i also stay don't undrestand
i have the following snippet of code of the certification bokk SCJP

Select the three correct answers.
(a) return a == o.a || b == o.b;
(b) return false;
(c) return a >= o.a;
(d) return a == o.a;
(e) return a == o.a && b == o.b;
the correct answer is b+d+e
i don't undrestand why these answers are correct and why a+c are not
iI have the snippet of following code

Which method header can be inserted at (1) so that the program compiles and runs
without errors?
Select the one correct answer.
(a) static <E extends CharSequence> Collection<? extends CharSequence>
delete4LetterWords(Collection<E> words)
(b) static <E extends CharSequence> List<E>
delete4LetterWords(Collection<E> words)
(c) static <E extends CharSequence> Collection<E>
delete4LetterWords(Collection<? extends CharSequence> words)
(d) static <E extends CharSequence> List<E>
delete4LetterWords(Collection<? extends CharSequence> words)
(e) static <E extends CharSequence> Collection<E>
delete4LetterWords(Collection<E> words)
(f) public <E super CharSequence> Collection<E>
delete4LetterWords(Collection<E> words)
the correct answer is (e)
please someone how telle me why the ather suggestion are not true i found a  confusion betwenn them to specify the correct answer