Program to count the frequency of a given letter in a string

/* Program to count the frequency of a given letter in a string. */

import java.io.DataInputStream;     // to load DataInputStream class        

class P22
{
    public static void main(String args[ ])
    {
        String str = new String();
        char ch='a';
        int len,count=0;
        DataInputStream in = new DataInputStream(System.in);

        try
        {
            System.out.print("Enter String : ");
            str = in.readLine();
            System.out.print("Enter a character to br searched in string : ");
            ch = (char)in.read();
            System.out.println(" String is : "+str);
           
        }
        catch(Exception e) {  System.out.println("I/O Error");   }

        len = str.length();
        for(int i =0;i<=len-1;i++)
            if(ch==str.charAt(i))
                count++;

        System.out.println(" Frequency of character '"+ch+"' in string is "+count);
    }
}