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Loop through the list of objects to get attribute.  RSS feed

 
Greenhorn
Posts: 25
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I have a class Student


and another class with list.


I am trying to loop through the List to find student == my Entered student number.



How can i list through the list??
 
Marshal
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Well, you can use a for-each loop for this purpose like below:



But this is not a good practice, because you can use Map classes instead of those List classes, so you can get the student quickly and in a smart-way without having a loop.

Devaka.
 
Kris Danielewski
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hmm

I have problem , it repeats enterMarkC for every Student in the list, check for student numbber work...
Currently I am trying to set the attribute of Student class (courseworkMark) by user input.
Looking forward for help with it.
 
Kris Danielewski
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Really need help with it , thanks...
 
Ranch Hand
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I would guess that what number equals after the statement "number = sc.next()" and what is returned by "if(s.getStudentNo().contains(number))" are not behaving the way you would like them to. Add some print statements to double check your input value and expected results. Also, I would add a break in your loop once you find the correct Student.

If this is for a class and you are allowed to go further I would definately use Devaka's suggestion to use a Map to make this much much easier. Each Student has a unique number... so you could skip the loop and find the correct Student in one statement using a Map.

HTH GL
 
Rancher
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Kris,

I'll third Brian and Devaka's suggestion to use one of the Map classes instead of a List. Lists are useful when ordering matters, like in a queue. Maps are much better when it comes to searching.

John.
 
It is sorta covered in the JavaRanch Style Guide.
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