Java Concept Of The Day

Given a string, your code must find out the first repeated as well as non-repeated character in that string. For example, if “JavaConceptOfTheDay” is the given string, then ‘J’ is a first non-repeated character and ‘a’ is a first repeated character.  Have a look at the below image.
repeated and non-repeated character

How To Find First Repeated And Non-Repeated Character In A String?

Step 1 : Define one HashMap called charCountMap with Character as key and Integer as value. This map will hold the characters and their count in the given string.
Step 2 : Convert inputString to char array called strArray.
Step 3 : Iterate through all chars of strArray and update their occurrences in charCountMap.
Step 4 : Iterate through all chars of strArray and check their count in charCountMap. Any first occurring character with 1 as it’s count will be the first non-repeated character in inputString.
Step 5 : Iterate through all chars of strArray and check their count in charCountMap. Any first occurring character with >1 as it’s count will be the first repeated character in inputString.
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
import java.util.HashMap;
import java.util.Scanner;
  
public class MainClass
{   
    static void firstRepeatedNonRepeatedChar(String inputString)
    {
       
         
        HashMap<Character, Integer> charCountMap = new HashMap<Character, Integer>();
         
      
         
        char[] strArray = inputString.toCharArray();
         
        
         
        for (char c : strArray)
        {
            if(charCountMap.containsKey(c))
            {
                //If char is present in charCountMap, incrementing it's count by 1
                 
                charCountMap.put(c, charCountMap.get(c)+1);
            }
            else
            {
               
                 
                charCountMap.put(c, 1);
            }
        }
         
        
        for (char c : strArray)
        {
            if (charCountMap.get(c) == 1)
            {
                System.out.println("First Non-Repeated Character In '"+inputString+"' is '"+c+"'");
                 
                break;
            }
        }
         
        for (char c : strArray)
        {
            if (charCountMap.get(c) > 1)
            {
                System.out.println("First Repeated Character In '"+inputString+"' is '"+c+"'");
                 
                break;
            }
        }
    }
     
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
         
        System.out.println("Enter the string :");
         
        String input = sc.next();
         
        firstRepeatedNonRepeatedChar(input);
    }
}
Output :
Enter the string :
JavaConceptOfTheDay
First Non-Repeated Character In ‘JavaConceptOfTheDay’ is ‘J’
First Repeated Character In ‘JavaConceptOfTheDay’ is ‘a’

Comments

Post a Comment

Popular posts from this blog

References and Resources java  1.  Java General Java mother site @  http://java.sun.com  (or  http://www.oracle.com/technetwork/java/index.html ). Java Developers' sites, in particular,  http://java.net . JDK  (aka  Java SE ) Java SE  mother site @  http://java.sun.com/javase  (or  http://www.oracle.com/technetwork/java/javase/overview/index.html ). JDK 7  API  Documentation Online @  http://download.oracle.com/javase/7/docs/api/index.html . JDK 7 Documentation Online @  http://download.oracle.com/javase/7/docs/ . Ken Arnold, James Gosling and David Holmes, "The Java Programming Language", 4th ed, 2005. (The defacto standard for Java Language, but does not seem to have been updated to cover the latest features?!) James Gosling, Bill Joy, Guy Steele and Gilad Bracha, "The Java Language Specification", 3rd ed, 2005. (The defacto standard for JVM, but does not seem to have been updated?!)...
Read more

What is string immutability?

Image
What is string immutability? Here are a set of diagrams to illustrate Java String's  immutability . 1. Declare a string String s = "abcd" ; s stores the reference of the string object. The arrow below should be interpreted as "store reference of". 2. Assign one string variable to another string variable String s2 = s ; s2 stores the same reference value, since it is the same string object. 3. Concat string s = s. concat ( "ef" ) ; s now stores the reference of newly created string object. Summary Once a string is created in  memory (heap), it can not be changed. We should note that all methods of String do not change the string itself, but rather return a new String. If we need a string that can be modified, we will need StringBuffer or StringBuilder. Otherwise, there would be a lot of time wasted for Garbage Collection, since each time a new String is created.  Here  is an example of StringBuilder u...
Read more
Java Question ..............? Q1. What is a cookie ? Ans. A cookie is a small piece of text stored on a user's computer by the browser for a specific domain. Commonly used for authentication, storing site preferences, and server session identification. Q2. Can we reduce the visibility of the overridden method ? Q3. What are different types of inner classes ? Ans. Simple Inner Class, Local Inner Class, Anonymous Inner Class , Static Nested Inner Class. Q4. Difference between TreeMap and HashMap ? Ans. They are different the way they are stored in memory. TreeMap stores the Keys in order whereas HashMap stores the key value pairs randomly. Q5. What is the difference between List, Set and Map ? Ans. List - Members are stored in sequence in memory and can be accessed through index. Set - There is no relevance of sequence and index. Sets doesn't contain duplicates whereas multiset can have duplicates. Map - Contains Key , Value pairs. Q6. Difference between Public...
Read more