Чигооо?

for (int i = 0; i < 10; i++){
...
}

package com.javarush.task.task07.task0712;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.Collections;
/*
Самые-самые
*/

public class Solution {
    public static void main(String[] args) throws IOException {
        //напишите тут ваш код
        Scanner some = new Scanner(System.in);
        ArrayList<String> list = new ArrayList<>(10);
        for (int i = 0; i < 10; i++){
            list.add(some.nextLine());
        }
        ArrayList<Integer> themost = new ArrayList<Integer>();
        for (int i = 0; i < list.size(); i++){
            themost.add(list.get(i).length());
        }
        Collections.sort(themost);
        int thesmallest = themost.get(0);
        int thegreatest = themost.get(themost.size()-1);
        for (int i = 0; i < list.size(); i++){
            if (list.get(i).length() == thesmallest){
                System.out.println(list.get(i));
                break;}
            else if (list.get(i).length() == thegreatest){
                System.out.println(list.get(i));
                break;
            }
            else{}
        }
    }
}