Question

USING JAVA

Consider the following methods:
StringBuilder has a method append(). If we run:
StringBuilder s = new StringBuilder();
s.append("abc");
The text in the StringBuilder is now "abc"
Character has static methods toUpperCase() and toLowerCase(), which convert characters to upper or lower case. If we run Character x = Character.toUpperCase('c');, x is 'C'.
Character also has a static isAlphabetic() method, which returns true if a character is an alphabetic character, otherwise returns false.
You will also need String's charAt() method, which returns the character at a given index in the String. For example, "Godzilla".charAt(1) returns 'o'.

Write an application as follows:
public static String getNonAlpha() takes a String as a parameter, builds a StringBuilder consisting of only the nonalphabetic characters in the String, and returns a String based on the StringBuilder (eg, sb.toString())
public static String getUpper() takes a String, builds a StringBuilder of the upper case versions of all the alphabetic characters in the String, and returns a String based on the StringBuilder.
Write JUnit tests to verify that the above methods are correct

Answer 1

import static org.junit.Assert.assertEquals;

public class StringOperations {
   public static void main(String[] args) {
//       Write JUnit tests to verify that the above methods are correct
       assertEquals("@324!", getNonAlpha("Test@324!"));
       assertEquals("TEST@324", getUpper("Test@324"));
   }
//   public static String getNonAlpha() takes a String as a parameter,
//   builds a StringBuilder consisting of only the nonalphabetic characters in the String,
//   and returns a String based on the StringBuilder (eg, sb.toString())
   public static String getNonAlpha(String str) {
       StringBuilder sb = new StringBuilder();
       for(int i=0;i<str.length();i++)
           if(!Character.isAlphabetic(str.charAt(i))) sb.append(str.charAt(i));
       return sb.toString();
   }
//   public static String getUpper() takes a String, builds a StringBuilder of the upper case
//   versions of all the alphabetic characters in the String, and returns a String based on the StringBuilder.
   public static String getUpper(String str) {
       StringBuilder sb = new StringBuilder();
       for(int i=0;i<str.length();i++)
           sb.append(Character.toUpperCase(str.charAt(i)));
       return sb.toString();
   }
}