Question

Objectives

By the end of this program, the student will have demonstrated the ability to

• Write static methods
• Use methods in a different class
• Write a sentinel-controlled loop
• Write nested if/else statements
• Manipulate Strings by character position

StringUtils

You are to complete the class StringUtils, which is in the attached zip file. Add the following public static methods:

copy

Write a method String copy(String currentString, int startPosition, int onePastLastPosition). This method returns a substring of currentString, including startPosition, but ending before onePastLastPosition. For example, copy(“abcd”, 1, 3) returns the String “bc”

cut

Write a method String cut(String currentString, int startPosition, int onePastLastPosition). This method returns a String constructed by starting with currentString, and removes the letters starting with startPosition and stopping before onePastLastPosition. For example, cut(“abcd”, 1, 3) returns the String “ad”

paste

Write a method String paste(String currentString, int insertBefore, String stringToInsert). This method returns the String constructed by inserting stringToInsert into currentString before position insertBefore. For example, paste(“ad”, 1, “bc”) returns the String “abcd”

StringMangle

You are to write a class StringMangle that has only a main method. This program allows a user to enter a String that we’ll call currentString. It maintains another String that we’ll call clipboard. The program asks the user to enter currentString. It then uses a sentinel-controlled loop to ask the user to enter one of four commands:

• c – copies part of currentString into clipboard using the copy method above. It asks the user for the starting and one-past the ending positions in currentString.
• x – assigns a new value to currentString using the cut method above. It asks the user for the starting and one-past the ending positions in currentString.
• v – assigns a new value to currentString using the paste method above to insert the clipboard into currentString. It asks the user for the starting position in currentString.
• q – quits the program.

Notes

• You may assume that the user enters valid input
• Use Scanner’s next() method to read the currentString from the user. This means that we won’t have spaces in the currentString.
• Use StringUtils.genGauge to output currentString to the user. It puts character positions (mod 10) underneath the currentString’s characters to help the user enter data. For example, System.out.println(StringUtils.genGauge(currentString));
• Write this program in baby steps. There are many ways to approach writing this program, but whichever order you use, write something and test it immediately. For example, if you decide to write the methods first, write one method and test it. Then write another and test it. And so on. When writing your main method, if you write the loop first, start by implementing the ‘q’ command and test it, then move to another command and test it. It’s better to have something that works, though it’s incomplete, than to have something complete that has nothing working.

Grading Elements

• All class and method names are correct
• All method signatures are correct
• All methods are in the correct class
• All methods return the proper value
• All methods are public static
• The main method uses a sentinel-controlled loop
• The main method prompts the user for commands c, x, v, q
• The main method handles each command appropriately
• The main method displays the currentString and clipboard before asking the user for a command
• The program terminates when the user enters ‘q’
• The main method uses StringUtils.genGauge to output the currentString

Sample Execution

Enter a string

fghdeabc

The current string is

fghdeabc

01234567

Enter c to copy, x to cut, v to paste, q to quit

C

Enter the starting position

5

Enter one past the ending position

8

The current string is

fghdeabc

01234567

The clipboard is

abc and it has length of 3

Enter c to copy, x to cut, v to paste, q to quit

v

Enter the position the paste should come before

0

The current string is

abcfghdeabc

01234567890

The clipboard is

abc and it has length of 3

Enter c to copy, x to cut, v to paste, q to quit

c

Enter the starting position

6

Enter one past the ending position

8

The current string is

abcfghdeabc

01234567890

The clipboard is

de and it has length of 2

Enter c to copy, x to cut, v to paste, q to quit

v

Enter the position the paste should come before

3

The current string is

abcdefghdeabc

0123456789012

The clipboard is

de and it has length of 2

Enter c to copy, x to cut, v to paste, q to quit

x

Enter the starting position

8

Enter one past the ending position

13

The current string is

abcdefgh

01234567

The clipboard is

de and it has length of 2

Enter c to copy, x to cut, v to paste, q to quit

q

START UP CODE:

public class StringUtils {
        
        public static String genGauge(String sb) {
                String strAndGauge = sb + "\n";
                for (int i = 0; i < sb.length(); i++) {
                        strAndGauge += (i % 10);
                }
                return strAndGauge;
        }

}

Answer 1

Explanation::

• Code in JAVA is given below
• Please read comments for better understanding of the code
• OUTPUT is given at the end of the code

Code in JAVA::

StringUtils.java CODE:

public class StringUtils {
   public static String genGauge(String sb) {
       String strAndGauge = sb + "\n";
       for (int i = 0; i < sb.length(); i++) {
           strAndGauge += (i % 10);
       }
       return strAndGauge;
   }
   public static String copy(String currentString, int startPosition, int onePastLastPosition) {
       String answer="";
       for(int i=startPosition ; i<onePastLastPosition;i++) {
           answer=answer+currentString.charAt(i);
       }
       return answer;
   }
   public static String cut(String currentString, int startPosition, int onePastLastPosition) {
       String answer="";
       for(int i=0;i<currentString.length();i++) {
           if(i<startPosition || i>=onePastLastPosition) {
               answer=answer+currentString.charAt(i);
           }
       }
       return answer;
   }
   public static String paste(String currentString, int insertBefore, String stringToInsert) {
       String answer="";
       for(int i=0;i<currentString.length();i++) {
           if(i==insertBefore) {
               for(int j=0;j<stringToInsert.length();j++) {
                   answer=answer+stringToInsert.charAt(j);
               }
           }
           answer=answer+currentString.charAt(i);
       }
       return answer;
   }
}

StringMangle.java CODE:

import java.util.Scanner;

public class StringMangle {

   public static void main(String[] args) {
       /**
       * Scanner class object named sc is declared and it is used to take input
       * from the user
       * */
       Scanner sc=new Scanner(System.in);
      
       /**
       * A String named currentString is declared below
       * And also another String named clipboard is also declared
       * */
       String currentString,clipboard="";
      
       /**
       * Prompting user to enter the string and it is stored in currentString
       * */
       System.out.println("Enter a string");
       currentString=sc.next();
       /**
       * Printing once the currentString
       * */
       System.out.println("The current string is");
       System.out.println(StringUtils.genGauge(currentString));
       /**
       * Three integer named startPosition, onePastLastPosition and insertBefore
       * are declared below
       * */
       int startPosition, onePastLastPosition, insertBefore;
       /***
       * Following while loop runs until user do not enter 'q' to end the loop
       */
       while(true) {
           /**
           * Prompting user to enter the choice of user
           * */
           System.out.println("Enter c to copy, x to cut, v to paste, q to quit");
           char ch=sc.next().charAt(0);
          
           /**
           * Converting the ch char to lower case
           * */
           ch=Character.toLowerCase(ch);
           if(ch=='q') {
               /**
               * If user choice is q then we break the loop
               * */
               break;
           }else if(ch=='c' || ch=='x') {
               /**
               * Prompting user to enter the starting position
               * and then one past the ending position
               * */
               System.out.println("Enter the starting position");
               startPosition=sc.nextInt();
              
               System.out.println("Enter one past the ending position");
               onePastLastPosition=sc.nextInt();
               if(ch=='c') {
                   /**
                   * Calling the copy method and passing the parameters
                   * Returned value is stored in clipboard
                   * */
                   clipboard=StringUtils.copy(currentString, startPosition, onePastLastPosition);
               }else {
                   currentString=StringUtils.cut(currentString, startPosition, onePastLastPosition);
               }
           }else if(ch=='v') {
               /**
               * Prompting user to enter the position the paste should come before
               * */
               System.out.println("Enter the position the paste should come before");
               insertBefore=sc.nextInt();
               /**
               * Calling paste method and storing the returned value in currentString
               * */
               currentString=StringUtils.paste(currentString, insertBefore, clipboard);
           }
           /**
           * Printing currentString and clipboard
           **/
           System.out.println("The current string is");
           System.out.println(StringUtils.genGauge(currentString));
           System.out.println("The clipboard is");
           System.out.println(clipboard+" and is has length of "+clipboard.length());
       }/*While ends here*/
   }
}

OUTPUT::
Enter a string
fghdeabc
The current string is
fghdeabc
01234567
Enter c to copy, x to cut, v to paste, q to quit
C
Enter the starting position
5
Enter one past the ending position
8
The current string is
fghdeabc
01234567
The clipboard is
abc and is has length of 3
Enter c to copy, x to cut, v to paste, q to quit
v
Enter the position the paste should come before
0
The current string is
abcfghdeabc
01234567890
The clipboard is
abc and is has length of 3
Enter c to copy, x to cut, v to paste, q to quit
c
Enter the starting position
6
Enter one past the ending position
8
The current string is
abcfghdeabc
01234567890
The clipboard is
de and is has length of 2
Enter c to copy, x to cut, v to paste, q to quit
v
Enter the position the paste should come before
3
The current string is
abcdefghdeabc
0123456789012
The clipboard is
de and is has length of 2
Enter c to copy, x to cut, v to paste, q to quit
x
Enter the starting position
8
Enter one past the ending position
13
The current string is
abcdefgh
01234567
The clipboard is
de and is has length of 2
Enter c to copy, x to cut, v to paste, q to quit
q

Please provide the feedback!!

Thank You!!