Here is a java example that reads a string from the command prompt and find the frequency of the character e in the input string.

import java.io.*;

class FindFrequencyOFCharacter 
{
    public static void main(String[] args) 
    {
        try{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        System.out.print("Enter String: ");
        String st=br.readLine();
        int count=0;
        char ch[]=st.toCharArray();
        for(int i=0;i<ch.length;i++){
            if(ch[i]=='e'){
                count++;
            }
        }
        System.out.println("Frequency of character e is: "+count);
        }
        catch(Exception e){}
    }
}