Preview:
import java.util.*;

class Solution {
    public static void main(String[] args) {
        String str = "sinstriiintng";

        int[] counts = new int[26];

        for (int i = 0; i < str.length(); i++)
            counts[str.charAt(i) - 'a']++;

        for (int i = 0; i < 26; i++)
            if (counts[i] > 1)
                System.out.println((char)(i + 'a') + " - " + counts[i]);
    }
}
downloadDownload PNG downloadDownload JPEG downloadDownload SVG

Tip: You can change the style, width & colours of the snippet with the inspect tool before clicking Download!

Click to optimize width for Twitter