Is there a class in Java which keeps duplicates but not order of data?

user_12153632 0
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I am dealing with anagrams so I'm concerned only with the characters present in the string but not their order. I searched for a suitable Collection class but in vain.

Can you please suggest any class that could help me to keep duplicates but ignores order?

anagram collections java
3 Answers

You can use a Map<Character,Integer> to count the number of occurrences of each character of a String. If the Maps generated for two Strings are equal, you'll know that the corresponding Strings are anagrams.

For example (here I used Map<Integer,Long> instead of Map<Character,Integer> since it was more convenient):

String one = "animal";
String two = "manila";
Map<Integer,Long> mapOne = one.chars ().boxed().collect(Collectors.groupingBy(Function.identity(),Collectors.counting()));
Map<Integer,Long> mapTwo = two.chars ().boxed().collect(Collectors.groupingBy(Function.identity(),Collectors.counting()));
System.out.println ("Is anagram? " + mapOne.equals(mapTwo));

Output:

Is anagram? true
user_12215710

You can use Google guava's HashMultiSet. The equals() method does exactly that:

Compares the specified object with this multiset for equality. Returns true if the given object is also a multiset and contains equal elements with equal counts, regardless of order. This implementation returns true if object is a multiset of the same size and if, for each element, the two multisets have the same count.

user_13641490

Instead of an ordered data structure, one can also dynamically sort the data.

As Unicode symbols, code points, are better than UTF-16 chars, I'll use Unicode ints instead:

int[] canonical(String s) {
    return s.codePoints().sorted().toArray();
}

boolean isAnagram(String s, String t) {
    return Arrays.equals(canonical(s), canonical(t));
}

boolean isAnagram(int[] s, String t) {
    return Arrays.equals(s, canonical(t));
}
user_9848230
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