find how many numberof times a character from a String is repeated in java

Question

I have a String of say, length is 5000. I want to find out the number of times the letter 'R' (Case Sensitive) is used. Below are the two passable solution...

Convert to char array, loop it to perform a condition to check and increment a counter.
Use Substring() with the character 'R' to get an array which could fetch a array. So, the total length of the array +1 will be number of times, the 'R' character in the string(This is not a better solution)

Help me out with the efficient solution on the cards for this. Thanks.

loop the String then test if it is `R` using the setCharAt(i) method of the String class — 0xDEADBEEF, Apr 07 '17 at 12:37
http://stackoverflow.com/questions/275944/java-how-do-i-count-the-number-of-occurrences-of-a-char-in-a-string --refer link should provide plenty of ways — Nandula, Apr 07 '17 at 12:46

score 6 · Answer 1 · answered Apr 07 '17 at 12:42

6

try this one

String text = "ABCabcRRRRRrrr";
int count = text.length() - text.replace("R", "").length();

answered Apr 07 '17 at 12:42

Pardeep

945
10
18

score 2 · Answer 2 · answered Apr 07 '17 at 12:41

2

If you're using java >= 8 you can use the Streams:

public static void main(String args[]) {
    String str= "abcderfgtretRetRotpabcderfgtretRetRotp"
    System.out.println(str.chars().filter(c -> c == 'R').count());
}

answered Apr 07 '17 at 12:41

Romain

301
2
7

Great. Thanks! Need to investigate on the internal logic. – Vijay L Marcelin Apr 07 '17 at 13:46

score 0 · Answer 3 · answered Apr 07 '17 at 12:40

0

String str = //the actual string
for(int i=0;i<str.length();++i)
{
    if(str.charAt(i)=='R')
    {
        capitalRCount++;
    }
}

answered Apr 07 '17 at 12:40

0xDEADBEEF

590
1
5
16

This is traditional way to check... any other trendy way with minimal processing time?? – Vijay L Marcelin Apr 07 '17 at 13:44
@VijayLMarcelin well I prepare logic because it exercise your mind plus when you know logic you can just do it with your logic instead of using many classes to adapt to.. – 0xDEADBEEF Apr 07 '17 at 13:52
Logics are always welcome... is there any api specific to resolve it further with quicker processing time. – Vijay L Marcelin Apr 07 '17 at 13:53

find how many numberof times a character from a String is repeated in java

3 Answers3