Programming and Algorithm : Find first Non repeated character in a string

possible solution to find non-repeated character in a string


package findFirstRepeatedCharInString;

import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

public class findFirstNonRepeatedCharInString {

/*=================================Solution1=========================*/
public static char firstNonRepeatingCharacterInString1(String str) {
boolean found;
char[] chars = str.toCharArray();
for (int i = 0; i < chars.length; i++) {
found = false;
for (int j = 0; j < chars.length; j++) {
found = (i != j) && (chars[i] == chars[j]);
if (found) {
break;
}
}
if (!found) {
return chars[i];
}
}
return '-';
}

/*===================================solution2========================*/
public static char firstNonRepeatingCharacterInString2(String str) {
Set<Character> chSet = new LinkedHashSet<Character>();
char[] charArray = str.toCharArray();
for (int i = 0; i < charArray.length; i++) {
if (!chSet.add(charArray[i])) {
chSet.remove(charArray[i]);
}
}
if (chSet.isEmpty())
return '-';
else
return (Character) (chSet.toArray())[0];
}

/*=============================================================*/

/*============================solution 3===============================*/
/* To find first non repeating character in a string
     * eg: if string is 'total' then 'o' is the answer
     * eg: if string is 'tweetwer' then 'r' is the answer
     * time complexity :
     * space complexity;
     */
    public static char firstNonRepeatingCharacterInString3(String s) {
        if (s == null)
            return '-';
        Map<String, Integer> inputMap = new HashMap<String, Integer>();
        for(int i=0; i < s.length(); i++) {
            String key = s.substring(i, i+1);
            if (inputMap.get(key) == null) {
                inputMap.put(key, new Integer(0));
            }
            else {
            int it = inputMap.get(key)+1;
                inputMap.put(key, it);
            }
        }
        //Now start from the start of the string and find the character which has count 1
        // first in order from left to right
        boolean found = false;
        String nonRepeatingStr = null;
        for(int i=0; i < s.length(); i++) {
            String key = s.substring(i, i+1);
            if(inputMap.get(key) == 0) {
            nonRepeatingStr = key;
            found= true;
                break;
            }
        }
        if(found){
        return nonRepeatingStr.toCharArray()[0];
        }
        return '-';
    }
 
 

/*==============================================================*/

public static void main(String[] args) {
System.out.println(firstNonRepeatingCharacterInString1("abcxafabc"));
System.out.println(firstNonRepeatingCharacterInString2("abcxafabc"));
System.out.println(firstNonRepeatingCharacterInString3("abcxafabc"));

System.out.println("====================================");
System.out.println(firstNonRepeatingCharacterInString1("tweetwer"));
System.out.println(firstNonRepeatingCharacterInString2("tweetwer"));
System.out.println(firstNonRepeatingCharacterInString3("tweetwer"));

System.out.println("====================================");
System.out.println(firstNonRepeatingCharacterInString1("total"));
System.out.println(firstNonRepeatingCharacterInString2("total"));
System.out.println(firstNonRepeatingCharacterInString3("total"));


}

}