Re: How to check variables for uniqueness ?

Patricia Shanahan <>
Thu, 21 Dec 2006 11:30:33 GMT
John Ersatznom wrote:

Andrew Thompson wrote:

Patricia Shanahan wrote:

Andrew Thompson wrote: wrote:

I have eight variables : var1, var2... var 8. All types String.
How to check that each variables has unique values ?

One way would be to create a Map, iterate the
var's and if not present in the map, add the value
as a key, else return false.


Any particular reason for Map, rather than Set?

You mean besides, 'lack of enough consultation
of the relevant docs.'? ;-)

Note that the result of a Set add call is true if, and only if, the
value is not already in the Set.

A Set sounds the go - it is just right for this task.

HashSet<String> foo = new HashSet<String>();
if (foo.size() < 8)

If you actually need to identify the specific duplicate pairs, you need
to compare them one by one -- 1 with all the others, 2 with all the
higher-numbered ones, and so on up to 7 and 8, using equals().

To save repititious writing, I'm going to assume the strings are in an
array. The equivalent of your code would be:

HashSet<String> foo = new HashSet<String>();
for(String v:vars){
if (foo.size() < vars.length)

You can simplify finding specific duplicates by checking the foo.add

HashSet<String> foo = new HashSet<String>();
for(int i=0; i<vars.length; i++){
     for(int j=0; j<i; j++){

A true result from foo.add means the string was actually added to the
set, so it has no duplicate with a lower index.


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