Question

You will need to think about problem solving. There are several multi-step activities.

Design, compile and run a single Java program, StringEx.java, to accomplish all of the following tasks. Add one part at a time and test before trying the next one. The program can just include a main method, or it is neater to split things into separate methods (all static void, with names like showLength, sentenceType, lastFirst1, lastFirst), and have main call all the ones you have written so far (or for testing purposes, just the one you are working on, with the other function calls commented out). Use the UI class for user input. You can copy the file into your project.

1. Read a string from the keyboard and print the length of the string, with a label.

2. Read a sentence (string) from a line of input, and print whether it represents a declarative sentence (i.e. ending in a period), interrogatory sentence (ending in a question mark), or an exclamation (ending in exclamation point) or is not a sentence (anything else).

   It makes sense to only make small changes at once and build up to final code. First you might just code it to check if a sentence is declarative or not. Then remember you can test further cases with else if (...).

3. Read a whole name from a single line of user input. Do not ask for first and last names to be entered on separate lines! Assume first and last names are separated by a space (no middle name). Print last name first followed by a comma and a space, followed by the first name. For example, if the input is "Marcel Proust", the output is "Proust, Marcel".

4. Improve the previous part, so it also allows a single name without spaces, like "Socrates", and prints the original without change. If there are two parts of the name, it should work as in the original version.

UI Class:

import java.util.Scanner;

/**
 * Aid user keyboard input with prompts and error catching.
 *  
 * @version 2017.09.24
 */
public class UI 
{
   private static Scanner in = new Scanner(System.in);

   /** Return the Scanner reading the keyboard.
    *  There should be ONLY ONE in a program.
    */
   public static Scanner getKeyboardScanner()
   {
      return in;
   }


   /** Prompt the user for a line and return the line entered.
    *  @param prompt
    *      The prompt for the user to enter the input line.
    *  @return
    *      The line entered by the user.
    */
   public static String promptLine(String prompt) {
      System.out.print(prompt);
      return in.nextLine();
   }


   /** Prompt for a character.
    *  @param prompt
    *      The prompt for the user to enter a character
    *  @return
    *     The first character of the line entered or a blank if the line
    *     is empty.
    */
   public static char promptChar(String prompt)
   {
      String line = promptLine(prompt);
      if (line.length() == 0)
         return ' ';
      return line.charAt(0);
   }

   /** Print a question and return a response.
    *  Repeat until a valid answer is given.
    * @param question
    *    The yes/no question for the user to answer.
    * @return
    *    True if the answer is yes, or False if it is no.
    */
   public static boolean agree(String question)
   {
      String yesStr = "yYtT", noStr = "nNfF", 
             legalStr = yesStr + noStr;

      char ans = promptChar(question);
      while (legalStr.indexOf(ans) == -1)
      {
         System.out.println("Respond 'y or 'n':");
         ans = promptChar(question);

      }
      return yesStr.indexOf(ans) >= 0;
   }

   /** Prompt and read an int.
    * Repeat until there is a legal value to return.
    * Read through the end of the line
    *  @param prompt
    *      The prompt for the user to enter a value.
    *  @return
    *      The value entered by the user.
    */
   public static int promptInt(String prompt)
   {
      System.out.print(prompt);
      while (! in.hasNextInt())
      {
         in.next();  // dump the bad token
         in.nextLine(); // dump through the newline
         System.out.println("!! Bad int format!!");
         System.out.print(prompt);
      }
      int val = in.nextInt();
      String rest = in.nextLine().trim(); //clear line
      if (rest.length() > 0)
          System.out.println("Skipping rest of input line.");
      return val;
   }

   /** Prompt and read a double.
    * Repeat until there is a legal value to return.
    *  @param prompt
    *      The prompt for the user to enter a value.
    *  @return
    *      The value entered by the user.
    */
   public static double promptDouble(String prompt)
   {
      System.out.print(prompt);
      while (! in.hasNextDouble())
      {
         in.next();  // dump the bad token
         in.nextLine(); // dump through the newline
         System.out.println("!! Bad double format!!");
         System.out.print(prompt);
      }
      double val = in.nextDouble();
      String rest = in.nextLine().trim(); //clear line
      if (rest.length() > 0)
          System.out.println("Skipping rest of input line.");
      return val;
   }

   /** Prompt and read a line of integers.
    * Repeat until there is a legal line to process.
    *  @param prompt
    *      The prompt for the user to enter data.
    *  @return
    *      The int values entered by the user.
    */
   public static int[] promptIntArray(String prompt)
   {
      while (true) { // exit via return statement
         String line = promptLine(prompt);
         String[] tokens = line.trim().split("\\s+");
         int n = tokens.length;
         int[] nums = new int[n];
         Scanner lineScan = new Scanner(line);
         int i = 0;
         while (i < n && lineScan.hasNextInt() )
         {
            nums[i] = lineScan.nextInt();
            i++;
         }
         if (i == n)
            return nums;
         System.out.format(
           "Bad input %s. Start your line over.\n", tokens[i]);
      }
   }

   /** Prompt and read a line of numbers.
    * Repeat until there is a legal line to process.
    *  @param prompt
    *      The prompt for the user to enter data.
    *  @return
    *      The double values entered by the user.
    */
   public static double[] promptDoubleArray(String prompt)
   {
      while (true) { // exit via return statement
         String line = promptLine(prompt);
         String[] tokens = line.trim().split("\\s+");
         int n = tokens.length;
         double[] nums = new double[n];
         Scanner lineScan = new Scanner(line);
         int i = 0;
         while (i < n && lineScan.hasNextDouble() )
         {
            nums[i] = lineScan.nextDouble();
            i++;
         }
         if (i == n)
            return nums;
         System.out.format(
           "Bad input %s. Start the line over.\n", tokens[i]);
      }
   }
}

Answer 1

/**
*
*/
package com.HomeworkLib;

import java.util.StringTokenizer;

/**
* @author vinoth.sivakumar
*
*/
public class StringEx {

   /**
   * @param args
   */
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       UI ui = new UI();
      
       //Read a string from the keyboard and print the length of the string, with a label.
       String inputString = ui.promptLine("Enter a String: ");
      
       System.out.println("Length of the String \"" +inputString +"\" is " + inputString.length());
      
       //Read a sentence (string) from a line of input
      
       inputString = ui.promptLine("Enter a sentence: ");      
       if(inputString.endsWith("."))
           System.out.println("The sentence entered is declarative ");
       else if (inputString.endsWith("?"))
           System.out.println("The sentence entered is interrogatory");
       else if(inputString.endsWith("!"))
           System.out.println("The sentence entered is exclamation ");
       else
           System.out.println("ITs not a sentence");
      
       //Read a whole name from a single line of user input
      
       String name = ui.promptLine("Enter Name: ");
      
       StringTokenizer st = new StringTokenizer(name, " ");
       if(st.countTokens() == 2) {
           String fname = st.nextToken();
           String lname = st.nextToken();
          
           System.out.println(lname+", " + fname);          
       }else {
           System.out.println(name);
       }
      
      
      
      
   }

}

----------------

Output 1

Enter a String: StringToFindLength
Length of the String "StringToFindLength" is 18
Enter a sentence: This sentence is to test type of sentence.
The sentence entered is declarative
Enter Name: Vinoth Sivakumar
Sivakumar, Vinoth
------------

Enter a String: ABCDFEGHIJ
Length of the String "ABCDFEGHIJ" is 10
Enter a sentence: WHERE ARE YOU FROM?
The sentence entered is interrogatory
Enter Name: OBAMA
OBAMA