# 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(System.in);

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

Output

```Enter the string: ABC
Permutations of ABC:
[ACB, BCA, ABC, CBA, BAC, CAB]```

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.