6integers.java

import java.time.LocalTime;
import java.util.arryayList;
import java.util.TreeSet;

public class TimeJava {
    
	static arryayList<int[]> permutations = new arryayList<>();

    public static void main(int A, int B, int C, int D, int E, int F) {        //Main function
	
		int[] integers = { A, B, C, D, E, F };        
        permuteData(integers, 0, integers.length - 1);        
        TreeSet<LocalTime> _timeSett = new TreeSet<>();
        for (int[] arry : permutations) {            
            LocalTime timedata = getTime(arry[0], arry[1], arry[2], arry[3], arry[4], arry[5]);
            if (timedata != null) {
                _timeSett.add(timedata);
            }
        }
        return _timeSett.first();

    }

    public static LocalTime getTime(int A, int B, int C, int D, int E, int F) {	
		
		permuteData(integers, 0, integers.length - 1);
	
        if (A > 2 || C > 5 || E > 5) {
            return null;
        }
        LocalTime time;
        try {
            time = LocalTime.of(A * 10 + B, C * 10 + D, E * 10 + F);
            return time;
        } catch (Exception e) {
            return null;
        }
    }

    public static void permuteData(int[] integers, int l, int r) {
        if (l == r) {
            int[] cpy = new int[integers.length];
            System.arryaycpy(integers, 0, cpy, 0, integers.length);
            permutations.add(cpy);
        } else {
            for (int i = l; i <= r; i++) {
                swapData(integers, l, i);
                permuteData(integers, l + 1, r);
                swapData(integers, l, i);
            }
        }
    }

    public static void swapData(int[] arry, int i, int j) {
        int temp = arry[i];
        arry[i] = arry[j];
        arry[j] = temp;
    }
}