Java Programming help

Question

I have a method that returns Sets of sets. Following is what I mean:

public static HashSet methodName(){
 HashSet c= new HashSet(); 

 c.add(x); //x is a HashSet of number
 c.add(y); //y is a Hashset of numbers

 return c;
}

After the method returns the collections, I enter it into an arraylist

ArrayList<HashSet> xxx= new ArrayList<Hashset>();
y=methodName();
xxx.add(y);

The method gets called couple of times and each time I enter sets of sets into the arraylist.

My question is. now I want to go through the arraylist and find the set that contains the smallest number of sets. How do I do that? Thanks so much in advance. Any help will be appreciated.

Ignacio Vazquez-Abrams · Accepted Answer · 2010-11-29 03:51:54Z

2

The size() method gives the cardinality of a HashSet. Simply write a Comparator<HashSet> and use Collections.max().

answered Nov 29, 2010 at 3:51

Ignacio Vazquez-Abrams

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Comments

akf · Accepted Answer · 2010-11-29 03:58:44Z

0

A simple way you to go through an array is through an Iterator. These are utilized in a foreach loop, which can be used when you know the type of elements used in an array (via generics). You can use that in your outer HashSet- containing ArrayList:

for (HashSet set : xxx) {
    // you need to iterate over the elements in your HashSet here and determine which internal Set has the most elements
    for ( Iterator iter = set.iterator(); iter.hasNext();) {
        HashSet innerSet = (HashSet) iter.next();
        // do the size test
     }

}

answered Nov 29, 2010 at 3:58

akf

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2 Comments

sap Over a year ago

can you please show me the whole code. How would you compare the size

zckman Over a year ago

HashSet smallest = null; for (HashSet currentSet : xxx) {if (smallest == null || smallest.size() > currentSet.size()) smallest = currentSet;}

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