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Sorting ArrayList Values inside a TreeMap

Dinesh Kumar Durairaj
Greenhorn

Joined: Dec 10, 2008
Posts: 5

I have a TreeMap<String, ArrayList<SampleVO>>

i need to sort by attributes in VO. How do i do that?

Here is the VO



Start from scratch and keep on scratching..
Seetharaman Venkatasamy
Ranch Hand

Joined: Jan 28, 2008
Posts: 5575

Welcome to Javaranch Dinesh

well, how do you sort ArrayList<SampleVO> ?
Dinesh Kumar Durairaj
Greenhorn

Joined: Dec 10, 2008
Posts: 5

Thanks for Welcoming me
seetharaman venkatasamy wrote:Welcome to Javaranch Dinesh

well, how do you sort ArrayList<SampleVO> ?


I need to sort the VOs in the ArrayList by some attribute of VO like id or name. or is it not possible ? :|

If input is
mapkey1,arrlistvo1->arrlistvo1(somevo1,somevo2...)->somevo1("xyz",1),somevo2("abc",2)

The result of sorting VO by name should be

mapkey1,arrlistvo1->arrlistvo1(somevo2,somevo1...)->somevo2("abc",2),somevo1("xyz",1)

The result of sorting VO by id should be

mapkey1,arrlistvo1->arrlistvo1(somevo1,somevo2...)->somevo1("xyz",1),somevo2("abc",2)

Marco Ehrentreich
best scout
Bartender

Joined: Mar 07, 2007
Posts: 1282

Hi Dinesh,

the general solution to your original problem is that you would define a Comparator for the TreeMap which is used to compare any two elements (=ArrayList<SampleVO>) of the TreeMap and decides which one should be before or after the other. But nevertheless YOU as a developer have to define what makes your ArrayLists comparable and defines the order when compared with another ArrayList.

Marco
Dinesh Kumar Durairaj
Greenhorn

Joined: Dec 10, 2008
Posts: 5

Thanks for the response, Marco

I implemented Comparator interface on the VO and override compareTo method based on your suggestion.

TreeMap values were sorted based on the keyname.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Sorting ArrayList Values inside a TreeMap