How to reverse a string using a while loop in java?

Question

I have a task, and I need to make the code take in a user inputted word, put it in capital letters, reverse and it output it. This is my code so far, but I really have no clue how I do it.

import java.util.Scanner;

public class WordSizeChecker {

    public static void main(String[] args) {
        Scanner kb = new Scanner (System.in);
        System.out.print("Please enter a word: ");
        String oword = kb.nextLine();
        String word = oword.toUpperCase();
        int length = word.length();
        int i = 0;
        while (i < length)
        {
            System.out.println(word.substring(i,length));
            length--;
        }

    }

}

Output:

Please enter a word: chess
CHESS
CHES
CHE
CH
C

Work it out on paper, as what you would do with a word like CHESS to reverse it. And turn that in a true algorithm. — Joop Eggen
– Joop Eggen, Commented Feb 6, 2016 at 23:30

thorshammer · Accepted Answer · 2016-02-07 00:19:29Z

2

new StringBuilder(oword).reverse().toString().toUpperCase();

or with a loop

oword = oword.toUpperCase();
for(int i = oword.length() - 1; i >= 0; i--)
{
    System.out.print(oword.charAt(i));
}
System.out.println();

edited Feb 7, 2016 at 0:19

answered Feb 6, 2016 at 23:31

thorshammer

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7 Comments

Gavriel Over a year ago

while this is a very nice answer, this doesn't use an explicit while loop as the homework requested :)

thorshammer Over a year ago

Overread that, you are right :) I recommend to use the charAt() function then.

HazirBot Over a year ago

Ahaha. Works for sure but i think its missing the excercise's point

thorshammer Over a year ago

I would have failed that exercise. What a shame :D Adapted the solution for the exercise as well.

Andreas Over a year ago

StringBuilder doesn't have a toUpperCase() method, so move it last.

|

Gavriel · Accepted Answer · 2016-02-06 23:35:50Z

0

public static void main(String[] args) {
    Scanner kb = new Scanner (System.in);
    System.out.print("Please enter a word: ");
    String oword = kb.nextLine();
    String word = oword.toUpperCase();
    int length = word.length();

    StringBuilder sb = new StringBuilder();
    // start from the end of the input string
    int i = length - 1;
    while (i >= 0) {
      // add the "next" character to the output
      sb.append(word.charAt(i));
      // step 1 character back
      i--;
    }
    System.out.println(sb.toString());
}

answered Feb 6, 2016 at 23:35

Gavriel

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6 Comments

Ingo Over a year ago

Try this with the String "𝖞𝖔𝖚 𝖓𝖊𝖊𝖉 𝖙𝖔 𝖈𝖔𝖓𝖘𝖎𝖉𝖊𝖗 𝖘𝖚𝖗𝖗𝖔𝖌𝖆𝖙𝖊 𝖈𝖍𝖆𝖗𝖆𝖈𝖙𝖊𝖗𝖘 𝖓𝖔𝖜𝖆𝖉𝖆𝖞𝖘"

Clashsoft Over a year ago

@Ingo in that case, you'd use StringBuilder#reverse(), though I doubt this is a requirement of his task.

Ingo Over a year ago

It is, as there are no restrictions of what the user may type.

Gavriel Over a year ago

What's the problem with unicode characters? It works.

Ingo Over a year ago

Not with the example string from above.

|

user5616935 · Accepted Answer · 2016-02-07 01:08:12Z

0

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

  System.out.println("Enter a string to reverse");
  original = in.nextLine();

  int length = original.length();

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

  System.out.println("Reverse of entered string is: "+reverse);

answered Feb 7, 2016 at 1:08

user5616935

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