Next Closest Time

https://www.lintcode.com/problem/next-closest-time/description

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Solution {
    /**
     * @param time: the given time
     * @return: the next closest time
     */
    public String nextClosestTime(String time) {
        // write your code here
        List<Integer> list = new ArrayList<>();
        char[] chars = time.toCharArray();
        for (int i = 0; i < time.length(); i++) {
            char c = time.charAt(i);
            if (Character.isDigit(c)) {
                int temp = c - '0';
                if (list.indexOf(temp) < 0) {
                    list.add(temp);
                }
            }
        }
        Collections.sort(list);
        for (int i = chars.length - 1; i >= 0; i--) {
            char c = chars[i];
            if (Character.isDigit(c)) {
                int temp = c - '0';
                int index = list.indexOf(temp) + 1;
                if (index == list.size()) {
                    chars[i] = (char) (list.get(0) + '0');
                } else {
                    char next = (char) (list.get(index) + '0');
                    if (i == 4) {
                        chars[i] = next;
                        return String.valueOf(chars);
                    } else if (i == 3 && next <= '5') {
                        chars[i] = next;
                        return String.valueOf(chars);
                    } else if (i == 1 && (chars[0] != '2' || chars[0] == '2' && next < '4')) {
                        chars[i] = next;
                        return String.valueOf(chars);
                    } else if (i == 0 && next < '2') {
                        chars[i] = next;
                        return String.valueOf(next);
                    }
                    chars[i] = (char) (list.get(0) + '0');
                }
            }
        }
        return String.valueOf(chars);
    }
}