How to find all the subsets of an array in java? [duplicate]

问题

This question already has answers here:

Obtaining a powerset of a set in Java (25 answers)

Closed 4 years ago.

I need to find all the subsets of an array using java.For e.g. if we have a set {1,2,3} then i should get {},{1},{2},{3},{1,2},{2,3},{1.3},{1,2,3}

回答1:

You can do this to avoid needing to recurse the solutions.

public static <T> void printCombinations(T[] arr) {
    for(long i = 0, max = 1L << arr.length; i < max; i++) {
        Set<T> ts = new HashSet<>();
        for(int j = 0; j < arr.length; j++) {
            if ((i >> j) != 0)
                ts.add(list.get(j));
        }
        System.out.println(ts);
    }
}

来源：https://stackoverflow.com/questions/29919846/how-to-find-all-the-subsets-of-an-array-in-java