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Print characters and their frequencies in order of occurrence using a LinkedHashMap in Java
  • Last Updated : 27 Jan, 2021

Given a string str containing only lowercase characters. The task is to print the characters along with their frequencies in the order of their occurrence in the given string.
Examples: 

Input: str = “geeksforgeeks” 
Output: g2 e4 k2 s2 f1 o1 r1
Input: str = “helloworld” 
Output: h1 e1 l3 o2 w1 r1 d1

Approach: Traverse the given string character by character and store the frequencies of all the strings in a LinkedHashMap which maintains the order of the elements in which they are stored. Now, iterate over the elements of the LinkedhashMap and print the contents.
Below is the implementation of the above approach:  

Java

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// Java implementation of the approach
import java.util.LinkedHashMap;
 
public class GFG {
 
    // Function to print the characters and their
    // frequencies in the order of their occurrence
    static void printCharWithFreq(String str, int n)
    {
 
        // LinkedHashMap preserves the order in
        // which the input is supplied
        LinkedHashMap<Character, Integer> lhm
            = new LinkedHashMap<Character, Integer>();
 
        // For every character of the input string
        for (int i = 0; i < n; i++) {
 
            // Using java 8 getorDefault method
            char c = str.charAt(i);
            lhm.put(c, lhm.getOrDefault(c, 0) + 1);
        }
 
        // Iterate using java 8 forEach method
        lhm.forEach(
            (k, v) -> System.out.print(k + " " + v));
    }
 
    // Driver code
    public static void main(String[] args)
    {
        String str = "geeksforgeeks";
        int n = str.length();
 
        printCharWithFreq(str, n);
    }
}

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Output: 

g2 e4 k2 s2 f1 o1 r1

 

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