Write a class of static methods that accomplish the followin

Write a class of static methods that accomplish the following tasks. In all cases do not look for built-in methods that accomplish the task, use loops as well as String and Character methods to get the tasks done. reverse (String s):String take a String as an argument and return the String reversed. Eg. \"Hello\" would be returned as \"olleH\". binary ToDecimal(String s):int take a String as an argument and return the decimal equivalent as an integer. If any of the characters are neither zero nor one return null. Eg. \"1000\" would return 8. \"10001\" would return 17. \"111111\" would return 63. \"111112\" would return -1. \"100001.1\" would return -1. initials (String s):String take a String as an argument and return a properly \"initialized\" and capitalized name. If the String does not contain exactly three names return null. Eg. \"James tiBeriUs kiRK\" would return \"J T. Kirk\". \"jean luc picard\" would return \"J. L. Picard\". \"AaroN LANGille\" would return null. mostFrequent (String s):char take a String and return the Character that occurs most frequently. In the event of a tie, return the last character that was checked in the tie. replace Substring(String s1, String s2, String s3):String take three Strings as arguments. The first String is the user\'s \"text\". The second String is a pattern to look for. Make all Strings lowercase in the method to facilitate search and replace. The third String is a pattern to replace the second String with. Eg: \"the dog jumped over the fence\" as the first String, \"the\" as the second and \"that\" as the third. Returned String is \"that dog jumped over that fence\". Write a tester class that shows off all of your methods. Be sure that errors (input that results in null) are handled properly.

Solution

package com.tt.tester;

public class StringTools {

   public static String reverse(String name) {

       StringBuilder builder = new StringBuilder();
       builder.append(name);
       builder = builder.reverse();

       String reverseString = builder.toString();

       return reverseString;
   }

   public static int binaryToDecimal(String s) {
       int bin = Integer.parseInt(s);

       int dec = 0;
       int power = 0;

       while (true) {

           if (bin == 0) {

               break;

           } else {

               int tmp = bin % 10;
               dec += tmp * Math.pow(2, power);
               bin = bin / 10;
               power++;

           }
       }
       return dec;

   }

   public static String[] initials(String s) {
       int count = 0;

       String[] sstring = s.split(\"\\\\s+\");
       for (String s1 : sstring) {
           count++;

       }
       if (count == 3) {
           return sstring;
       } else
           return null;
   }

   public static String mostFrequent(String s) {
       char[] charray = s.toCharArray();
       int maximumCount = 1;
       char maximumChar = charray[0];
       for (int i = 0, k = 0; i < s.length() - 1; i = k) {
           int counts = 1;
           while (++k < s.length() && charray[i] == charray[k]) {
               counts++;
           }
           if (counts > maximumCount) {
               maximumCount = counts;
               maximumChar = charray[i];
           }
       }
       return (maximumChar + \" = \" + maximumCount);
   }

}

package com.tt.tester;

public class StringTester {

   public static void main(String[] args) {

       StringTools tools = new StringTools();
       String r = tools.reverse(\"mark\");
       System.out.println(\"the reverse of a string is \" + r);
       int r1 = tools.binaryToDecimal(\"10011\");
       System.out.println(\"the decimal is \" + r1);

       String[] s = tools.initials(\"ramu ramum ramesh\");
       if (s != null) {
           for (String string : s) {
               System.out.println(\"the string are \" + string);
           }
       }

       String s2 = tools.mostFrequent(\"ramusramusr\");
       System.out.println(s2.toString());

   }

}

output

the reverse of a string is kram
the decimal is 19
the string are ramu
the string are ramum
the string are ramesh
r = 1