Below program prints the possible permutations in given String using Java:

public class StringPermutations {
 
	public static void main(String[] args) {
		String str = "ABC";
		int len = str.length();
		permute(str, 0, len - 1);
	}
 
	private static void permute(String str, int left, int right) {
		if (left == right) {
			System.out.println(str);
		} else {
			for (int i = left; i <= right; i++) {
				str = swap(str, left, i);
				permute(str, left + 1, right);
				str = swap(str, left, i);
			}
		}
	}
 
	private static String swap(String str, int i, int j) {
		char[] arr = str.toCharArray();
		char temp = arr[i];
		arr[i] = arr[j];
		arr[j] = temp;
		return String.valueOf(arr);
	}
 
}