(This program project comes from Chapter 11: Exceptions and Input/Output Operati

Question

(This program project comes from Chapter 11: Exceptions and Input/Output Operations in the book Java Illuminated)

Design a class that checks if a String is made of tokens of the same data type (for this, you may only consider four data types: boolean, int, double , or char ). This class has two instance variables: the String of data and its delimiter. Other than the constructor, you should include a method, checkTokens, that takes one parameter, representing the data type expected (for example, 0 could represent boolean , 1 could represent int , 2 could represent double , and 3 could represent char ). The method returns true if all the tokens in the String are of the specified data type; otherwise, it returns false.

Explanation / Answer

import java.util.Scanner;

public class StrToken {

   private String data;
   private String delimeter;

   public StrToken(String data, String delimeter) {
       this.data = data;
       this.delimeter = delimeter;
   }

   public boolean checkTokens(int type) {
       String dataToken[] = data.split(delimeter);
       // boolean
       if (type == 0) {
           for (String st : dataToken) {
               {
                   if (!("true".equalsIgnoreCase(st) || "false"
                           .equalsIgnoreCase(st))) {
                       return false;
                   }
               }
           }
       } else if (type == 1) {
           for (String st : dataToken) {
               try {
                   Integer.parseInt(st);
               } catch (Exception e) {
                   return false;
               }
           }
       } else if (type == 2) {
           for (String st : dataToken) {
               try {
                   Double.parseDouble(st);
                   if (!st.contains(".")) {
                       return false;
                   }
               } catch (Exception e) {
                   return false;
               }

           }
       } else if (type == 3) {
           for (String st : dataToken) {
               if (st.length() > 1) {
                   return false;
               }

               if (!Character.isLetter(st.charAt(0))) {
                   return false;
               }
           }
       }

       return true;
   }

   public static void main(String[] args) {
       StrToken s = new StrToken("121.3,322.3", ",");
       System.out.println(s.checkTokens(2));
   }
}

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