CODEWITHSUNDEEP
javaloops
dappers
dappers

Reputation: 23

How do I get this code to loop based off the user's input?

My code here checks whether or not the word that the user inputs is a palindrome or not. It executes properly its just that if the user tries to loop it by pressing "1". The program ends. How do I fix this?

int answer =0;

 String original, backwards = "";
  Scanner input = new Scanner(System.in);

  System.out.println("A palindrome is a word that is the same forwards as it is backwards. Enter     a word to check if it is a palindrome or not.");
  original = input.nextLine();

  int length = original.length();
 do {
  for ( int i = length - 1; i >= 0; i-- )
     backwards = backwards + original.charAt(i);

  if (original.equals(backwards))
     System.out.println("The entered phrase is a palindrome.");
  else
     System.out.println("The entered phrase is not a palindrome.");

}
  while (answer ==1);
  System.out.println("If you would like to check another word press 1. If you wish to exit, press     2.");
  answer = input.nextInt();
  if (answer ==1){
      System.out.println("Enter another word");
    }
 else if (answer == 2){
 System.out.println("Have a nice day");
 }
  }
 }

Here is a sample output of the program:

A palindrome is a word that is the same forwards as it is backwards. Enter a word to check if it is a palindrome or not.

racecar

The entered phrase is a palindrome.

If you would like to check another word press 1. If you wish to exit, press 2.

1

Enter another word

Upvotes: 1

Views: 205

Answers (5)

Munyari
Munyari

Reputation: 85

A do while loop works the same way as a regular while loop, except the first conditional check is omitted. If the condition in your while was met, then execution of the code in the do block would be continued. However, the while condition is never met, can you see why? Even if this condition was met, that's not the code you wanted executed next. The code below while is not a part of the do-while loop. You need to move the while to come after both of your conditional blocks at the end. The Java docs on while loops should be a useful read.

Upvotes: 0

Ensar Hatipoglu
Ensar Hatipoglu

Reputation: 193

You need to put the check if user want to enter another work in the while loop. But in the mean time, be careful to reset all variables to their original value, so it might be best to set them in the while loop as well. Something like this:

import java.util.Scanner;

public class Palidrome {
    public static void main(String[] args) {
        int answer = 0;

        Scanner input = new Scanner(System.in);
        String original;

        System.out
            .println("A palindrome is a word that is the same forwards as it is backwards. Enter     a word to check if it is a palindrome or not.");


        while( true ) {
            original = input.nextLine();
            String backwards = "";
            int length = original.length(); 

            for (int i = length - 1; i >= 0; i--)
                backwards = backwards + original.charAt(i);

            if (original.equals(backwards))
                System.out.println("The entered phrase " + original + " is a palindrome.");
            else
                System.out.println("The entered phrase " + original + " is not a palindrome.");

            System.out.println("If you wish to exit, press     2");
            answer = input.nextInt();

            if(answer == 2) {
                System.out.println("Have a nice day");
                break;
            }
            input.nextLine();
            System.out.println("Enter another word");
        }
        input.close();
    }
}

Upvotes: 0

BDRSuite
BDRSuite

Reputation: 1612

make the palindrome check as a method and then call the method if the user input is 1.

In your code , it does not do anything if the user inout is equal to 1.

i just used your scanner objects as it is. You can declare them in your class to use it in all the methods.

    public void palindrome(String S){

    int answer =0;

     String original, backwards = "";
      Scanner input = new Scanner(System.in);

      System.out.println("A palindrome is a word that is the same forwards as it is backwards. Enter     a word to check if it is a palindrome or not.");
      original = input.nextLine();

      int length = original.length();
     do {
      for ( int i = length - 1; i >= 0; i-- )
         backwards = backwards + original.charAt(i);

      if (original.equals(backwards))
         System.out.println("The entered phrase is a palindrome.");
      else
         System.out.println("The entered phrase is not a palindrome.");

    }
      while (answer ==1);


System.out.println("If you would like to check another word press 1. If you wish to exit, press     2.");
 int option= input.nextInt();
  if (option==1){
      System.out.println("Enter another word");
     String word= input.readLine();
      palindrome(word);
    }

Upvotes: 0

RealSkeptic
RealSkeptic

Reputation: 34618

Your loop finishes before the user gets to choose if he wants to enter 1 or 2. It is a do...while loop, so it ends at the while. So it executes only once - because as soon as a palindrome is checked, the next thing is to check whether the answer is 1. But the user has not entered either 1 or 2 at this point.

So you should move the } while ( answer == 1 ) part to the line after the closing of the if...else... that checks what the user answer was.

Also, if the answer was 1, you should ask for another input. The only place you ask for input is before the loop starts. If the user answered 1 you should run original = input.nextLine(); again. Be careful - you may need to run two input.nextLine(), as the scanner will think the rest of the line after the 1 or 2 is what you meant.

Upvotes: 2

Conanap
Conanap

Reputation: 179

Your scanner is asking for nextLine, but you're asking for an int. nextLine means it will take what is typed in the nextLine as a string.

Simple fix is replace 1 and 2 with characters a and b.

Complicated way is to parse string into integer.

Upvotes: 0

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