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# Java program to count the occurrences of each character

Write a Java program which prints number of occurrences of each characters and also it should not print repeatedly occurrences of duplicate characters as given in the example:
Examples:

```Input : geeksforgeeks
Output :
Number of Occurrence of g is:2
Number of Occurrence of e is:4
Number of Occurrence of k is:2
Number of Occurrence of s is:2
Number of Occurrence of f is:1
Number of Occurrence of o is:1
Number of Occurrence of r is:1```

Approach:

The idea is to create a count array of size 256. Traverse input string and for every character increment its count.

## JAVA

 `// Java program for the above approach``class` `NoOfOccurrenceOfCharacters {``    ``static` `final` `int` `MAX_CHAR = ``256``;` `    ``static` `void` `getOccurringChar(String str)``    ``{``        ` `        ``// Create an array of size 256``        ``// i.e. ASCII_SIZE``        ``int` `count[] = ``new` `int``[MAX_CHAR];` `        ``int` `len = str.length();` `        ``// Initialize count array index``        ``for` `(``int` `i = ``0``; i < len; i++)``            ``count[str.charAt(i)]++;` `        ``// Create an array of given String size``        ``char` `ch[] = ``new` `char``[str.length()];``        ``for` `(``int` `i = ``0``; i < len; i++) {``            ``ch[i] = str.charAt(i);``            ``int` `find = ``0``;``            ``for` `(``int` `j = ``0``; j <= i; j++) {` `                ``// If any matches found``                ``if` `(str.charAt(i) == ch[j])``                    ``find++;``            ``}` `            ``if` `(find == ``1``)``                ``System.out.println(``                    ``"Number of Occurrence of "``                    ``+ str.charAt(i)``                    ``+ ``" is:"` `+ count[str.charAt(i)]);``        ``}``    ``}``  ` `    ``// Driver Code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``String str = ``"geeksforgeeks"``;``        ``getOccurringChar(str);``    ``}``}`

Output

```Number of Occurrence of g is:2
Number of Occurrence of e is:4
Number of Occurrence of k is:2
Number of Occurrence of s is:2
Number of Occurrence of f is:1
Number of Occurrence of o is:1
Number of Occurrence of r is:1
```

Time complexity: O(n2)

Auxiliary Space: O(256)

Example: Count total number of character in the string.

## Java

 `/*package whatever //do not write package name here */` `import` `java.io.*;``import` `java.util.Scanner;``class` `Program {``    ``public` `static` `void` `main(String[] args)``    ``{``        ``Scanner in = ``new` `Scanner(System.in);``        ``String str=``"GeeksForGeeks"``; ``        ``System.out.println(``            ``"Total number of character in string is "``            ``+str.length());``    ``}``}`

Output

```Total number of character in string is 13
```

### Counting occurrence of letter in string using HashMap

In this approach we will use HashMap as well as ArrayList to count exact occurrence of letter in given String.

## Java

 `import` `java.io.*;``import` `java.util.*;` `class` `GFG {``    ``public` `static` `void` `main(String[] args)``    ``{``        ``String str = ``"GeeksForGeeks"``;``        ``ArrayList al = ``new` `ArrayList<>();``        ``for` `(``int` `i = ``0``; i < str.length(); i++) {``            ``al.add(str.charAt(i));``        ``}``        ``HashMap hm = ``new` `HashMap<>();``        ``for` `(``int` `i = ``0``; i < str.length(); i++) {``            ``hm.putIfAbsent(al.get(i),``                           ``Collections.frequency(al,al.get(i)));``        ``}` `        ``for` `(Map.Entry e : hm.entrySet()) {``            ``System.out.println(``                ``"Character is :"``+e.getKey()+ ``" and its count is string is "``+ e.getValue());``        ``}``    ``}``}`

Output

```Character is :r and its count is string is 1
Character is :s and its count is string is 2
Character is :e and its count is string is 4
Character is :F and its count is string is 1
Character is :G and its count is string is 2
Character is :k and its count is string is 2
Character is :o and its count is string is 1
```

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