# Finding all subsets of a given set in Java

**Problem:** Find all the subsets of a given set.

Input:S = {a, b, c, d}Output:{}, {a} , {b}, {c}, {d}, {a,b}, {a,c}, {a,d}, {b,c}, {b,d}, {c,d}, {a,b,c}, {a,b,d}, {a,c,d}, {b,c,d}, {a,b,c,d}

The total number of subsets of any given set is equal to 2^ (no. of elements in the set). If we carefully notice it is nothing but binary numbers from 0 to 15 which can be shown as below:

0000 | {} |

0001 | {a} |

0010 | {b} |

0011 | {a, b} |

0100 | {c} |

0101 | {a, c} |

0110 | {b, c} |

0111 | {a, b, c} |

1000 | {d} |

1001 | {a, d} |

1010 | {b, d} |

1011 | {a, b, d} |

1100 | {c, d} |

1101 | {a, c, d} |

1110 | {b, c, d} |

1111 | {a, b, c, d} |

Starting from right, 1 at ith position shows that the ith element of the set is present as 0 shows that the element is absent. Therefore, what we have to do is just generate the binary numbers from 0 to 2^n – 1, where n is the length of the set or the numbers of elements in the set.

`// A Java program to print all subsets of a set ` `import` `java.io.IOException; ` ` ` `class` `Main ` `{ ` ` ` `// Print all subsets of given set[] ` ` ` `static` `void` `printSubsets(` `char` `set[]) ` ` ` `{ ` ` ` `int` `n = set.length; ` ` ` ` ` `// Run a loop for printing all 2^n ` ` ` `// subsets one by one ` ` ` `for` `(` `int` `i = ` `0` `; i < (` `1` `<<n); i++) ` ` ` `{ ` ` ` `System.out.print(` `"{ "` `); ` ` ` ` ` `// Print current subset ` ` ` `for` `(` `int` `j = ` `0` `; j < n; j++) ` ` ` ` ` `// (1<<j) is a number with jth bit 1 ` ` ` `// so when we 'and' them with the ` ` ` `// subset number we get which numbers ` ` ` `// are present in the subset and which ` ` ` `// are not ` ` ` `if` `((i & (` `1` `<< j)) > ` `0` `) ` ` ` `System.out.print(set[j] + ` `" "` `); ` ` ` ` ` `System.out.println(` `"}"` `); ` ` ` `} ` ` ` `} ` ` ` ` ` `// Driver code ` ` ` `public` `static` `void` `main(String[] args) ` ` ` `{ ` ` ` `char` `set[] = {` `'a'` `, ` `'b'` `, ` `'c'` `}; ` ` ` `printSubsets(set); ` ` ` `} ` `} ` |

*chevron_right*

*filter_none*

Output:

{ } { a } { b } { a b } { c } { a c } { b c } { a b c }

**Related Post:**

Finding all subsets of a Set in C/C++

This article is contributed by **Nikhil Tekwani.** If you like GeeksforGeeks and would like to contribute, you can also write an article and mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

## Recommended Posts:

- Partition an array of non-negative integers into two subsets such that average of both the subsets is equal
- Divide array in two Subsets such that sum of square of sum of both subsets is maximum
- Sum of subsets of all the subsets of an array | O(3^N)
- Sum of subsets of all the subsets of an array | O(N)
- Sum of subsets of all the subsets of an array | O(2^N)
- Sum of XOR of all possible subsets
- Subsets having Sum between A and B
- Sum of bitwise AND of all possible subsets of given set
- Number of subsets with a given AND value
- Sum of the products of all possible Subsets
- Number of subsets with a given OR value
- Sum of average of all subsets
- Sum of the sums of all possible subsets
- Sum of bitwise OR of all possible subsets of given set
- Number of subsets with zero sum