Finding max value of Array

Question

I have two classes, DataClass and MY GUI Class.

This is in my GUI Class

 final ArrayList<DataClass> MarksData = new ArrayList<DataClass>();

I store 4 elements at a time [Mark1,Mark2,Mark3,Mark4]

How can I find all the maximum mark for Mark1

I tried Object obj = Collections.min() but doesn't work since it's an arrayList of type DataClass.

Any help is appreciated :)

• Bhavik Shah: how do you determine what is the maximum mark?
• Rohit Jain: What are Mark1, Mark2, and so on...? Show us the source code of DataClass.
• Hussain Akhtar Wahid 'Ghouri': simply traverse the list , take a temp variable storing the first array value , compare the two adjacent , if higher value is found replace it to temp var , in the end the temp var returns the max value , this is simple sorting algo
• Moe: @RohitJain Here is my dataClass pastebin.com/jfsuydQG
• Rohit Jain: @JamesHunter.. That link is not accessible in my office. You should post your code here. Try to extract relevant part and post taht.

Answer 1

The best way to do this would probably be to use Collections.max(), but to do this you need to implement Comparable<DataClass> on the DataClass class.

This interface lets you define a compareTo(DataClass o) method where you can write the logic in that method to determine if it's less or greater than the other mark, and then Collections.max() will take care of finding the maximum for you.

As noted in the comment, you can also write a custom comparator and use the variant of Collections.max() which takes that custom comparator - but the logic you write to compare the marks is the same.

Note that if you want to find the minimum mark instead, go for Collections.min(). All other details remain the same.

• Subir Kumar Sao: Or you can also write a Comparator. and use max(Collection coll, Comparator comp)
• Peter Lawrey: The question says "maximum mark" but it appears the OP wants the minimum which could be the "best mark"
• Michael Berry: @PeterLawrey Good point, missed that. Added a note about min() at the end.

Answer 2

To use Collections.min() you must either make DataClass implements Comparable<DataClass> or you must provide a custom Comparator<DataClass>