Java Program to Compute all the permutations of the string

To understand this example, you should have the knowledge of the following Java programming topics:

Permutation of the string means all the possible new strings that can be formed by interchanging the position of the characters of the string. For example, string ABC has permutations [ABC, ACB, BAC, BCA, CAB, CBA].

Example: Java program to get all the permutation of a string

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

class Main {
  public static Set<String> getPermutation(String str) {

    // create a set to avoid duplicate permutation
    Set<String> permutations = new HashSet<String>();

    // check if string is null
    if (str == null) {
      return null;
    } else if (str.length() == 0) {
      // terminating condition for recursion
      return permutations;

    // get the first character
    char first = str.charAt(0);

    // get the remaining substring
    String sub = str.substring(1);

    // make recursive call to getPermutation()
    Set<String> words = getPermutation(sub);

    // access each element from words
    for (String strNew : words) {
      for (int i = 0;i<=strNew.length();i++){

        // insert the permutation to the set
        permutations.add(strNew.substring(0, i) + first + strNew.substring(i));
    return permutations;

  public static void main(String[] args) {

    // create an object of scanner class
    Scanner input = new Scanner(;

    // take input from users
    System.out.print("Enter the string: ");
    String data = input.nextLine();
    System.out.println("Permutations of " + data + ": \n" + getPermutation(data));


Enter the string: ABC
Permutations of ABC: 

In Java, we have used the recursion to compute all the permutations of a string. Here, we store the permutation in a set Collection. So, there will be no duplicate permutation.

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