Java program to find First Non Repeated Occurrence using lambda expressions

This following program illustrate 4 different ways to find solution to the above problem. we will get back to find solution using  lambda expressions through fourth function.
Remember to set compiler path as java 8.

  NonRepeated.find("abhishek") will get it through indexOf and lastindexOf build in functions.
  NonRepeated.findsec("learnNShare") NonRepeated.findsec("learnNShare") are same only      difference is we are using HashMap and LinkedHashMap  respectively which in our case is not  making any difference.

  Finally findfourth("letseethistimel", System.out::print); makes use of lambda expressions to arrive at  solutions without making  use of second loop or build in functions.

  For now the complexity of each function is left to user to find. I will work on same and update this     post in near future.

/**
 *
 */
package com.abhishek.string;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.function.*;
import java.util.stream.Collectors;
import static java.util.function.Function.identity;
/**
 * @author Abhishek
 *
 */

/*
 * Java program to find First Non Repeated Occurrence using lambda expressions
 *
package com.abhishek.string;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.function.*;
import java.util.stream.Collectors;
import static java.util.function.Function.identity;
public class NonRepeated {

public NonRepeated() {

}

public static void main(String[] args) {

try {

//Hard coding input to illustrate various methods
char ch = NonRepeated.find("abhishek");
Character ch1 = NonRepeated.findsec("learnNShare");
Character ch2 = NonRepeated.findthird("learnNShare");
System.out.print(ch+" "+ch1+" "+ch2+" ");

//using java 8 feature lambda expression
findfourth("letseethistimel", System.out::print);
} catch (Exception e) {

e.printStackTrace();
}

}
public static char find(String pstr){
for( char ch: pstr.toCharArray()){
if(pstr.indexOf(ch)==pstr.lastIndexOf(ch)){
return ch;
}
}
return '/';
}
public static Character findsec(String pstr){
int len = pstr.length();
Character ch ;
HashMap<Character,Integer> chmap = new HashMap<Character,Integer>();
for(int i=0;i<len;i++){
ch = pstr.charAt(i);
if(chmap.containsKey(ch))
chmap.put(ch, chmap.get(ch)+1);
else
chmap.put(ch, 1);

}
for(int i=0;i<len;i++){
ch = pstr.charAt(i);
if(chmap.get(ch)==1)
return ch;
}
return null;
}
public static Character findthird(String pstr){
int len = pstr.length();
Character ch = 'a';
LinkedHashMap<Character,Integer> chmap = new LinkedHashMap<Character,Integer>();
for(int i=0;i<len;i++){
ch = pstr.charAt(i);
if(chmap.containsKey(ch))
chmap.put(ch, chmap.get(ch)+1);
else
chmap.put(ch, 1);

}
for(int i=0;i<len;i++){
ch = pstr.charAt(i);
if(chmap.get(ch)==1)
return ch;
}
return ch;
}
public static void findfourth(String pstr, Consumer<Character> callback) {
pstr.chars()
.mapToObj(in -> Character.valueOf((char) in))
.collect(Collectors.groupingBy(identity(), LinkedHashMap::new, Collectors.counting()))
.entrySet().stream()
.filter(entry -> entry.getValue() == 1L)
.map(entry -> entry.getKey())
.findFirst().map(cnt -> { callback.accept(cnt); return cnt; } );
}
}

Output will be
a l l h