Find the first non-repeating character within the string

Programming

package com.westudio.java;

import java.util.*;

/**
 * Created with IntelliJ IDEA.
 * User: tonyhe
 * Date: 14-5-28
 * Time: 上午10:56
 * To change this template use File | Settings | File Templates.
 */
public class Programming {

    public static char getFirstNonRepeatedChar(String str) {

        Map<Character, Integer> counts = new LinkedHashMap<Character, Integer>(str.length());

        for (char c : str.toCharArray()) {
            counts.put(c, counts.containsKey(c) ? counts.get(c) + 1 : 1);
        }

        for (Map.Entry<Character, Integer> entry : counts.entrySet()) {
            if (entry.getValue() == 1) {
                return entry.getKey();
            }
        }

        throw new RuntimeException("can't find any non repeated character");
    }

    public static char firstNonRepeatedChar(String str) {

        Set<Character> repeating = new HashSet<Character>();
        List<Character> noRepeating = new ArrayList<Character>();

        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);

            if (repeating.contains(c)) {
                continue;
            }

            if (noRepeating.contains(c)) {
                noRepeating.remove(noRepeating.indexOf(c));
                repeating.add(c);
            } else {
                noRepeating.add(c);
            }
        }

        return noRepeating.get(0);
    }

    public static char firstNonRepeatingChar(String str) {

        HashMap<Character, Integer> counts = new HashMap<Character, Integer>();

        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            if (counts.containsKey(c)) {
                counts.put(c, counts.get(c) + 1);
            } else {
                counts.put(c, 1);
            }
        }

        for (int j = 0; j < str.length(); j++) {
            char c = str.charAt(j);
            if (counts.get(c) == 1) {
                return c;
            }
        }

        throw new RuntimeException("can't find any non repeated character");
    }

    public static void main(String[] args) {
        System.out.println(Programming.getFirstNonRepeatedChar("hello"));
        System.out.println(Programming.firstNonRepeatedChar("Swiss"));
        System.out.println(Programming.firstNonRepeatingChar("aabcdcdbe"));
    }
}