Printing reverse of any String without using any predefined function?

Question

How to print the reverse of the String java is object orientated language without using any predefined function like reverse()?

I also think "any predefine function" is very vague... if you don't use **any** predefined functions, you're going to struggle to do *anything*. — Marc Gravell, Apr 10 '10 at 10:23
Furtunately Java only has Methods, it doesn't have functions. ;) — Peter Lawrey, Jul 24 '10 at 13:23
possible duplicate of [Whats the best way to recursively reverse a string in Java?](http://stackoverflow.com/questions/859562/whats-the-best-way-to-recursively-reverse-a-string-in-java) — , Sep 27 '11 at 15:15
refer http://learnjava-soa.blogspot.in/2016/02/write-java-program-without-using.html — madhu, Feb 15 '16 at 07:18

score 58 · Answer 1 · answered Apr 10 '10 at 12:52

58

This is the simplest solution:

System.out.print("egaugnal detatneiro tcejbo si avaj");

answered Apr 10 '10 at 12:52

Adriaan Koster

15,870
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9

This is what happens when people don't ask questions properly. – Cruncher Nov 18 '13 at 21:35
2

I think StackOverflow should implement smileys :) – subhashis Jan 31 '15 at 03:33

score 50 · Accepted Answer · edited Jul 30 '11 at 08:04

50

You can do it either recursively or iteratively (looping).

Iteratively:

 static String reverseMe(String s) {
   StringBuilder sb = new StringBuilder();
   for(int i = s.length() - 1; i >= 0; --i)
     sb.append(s.charAt(i));
   return sb.toString();
 }

Recursively:

 static String reverseMe(String s) {
   if(s.length() == 0)
     return "";
   return s.charAt(s.length() - 1) + reverseMe(s.substring(0,s.length()-1));
 }

edited Jul 30 '11 at 08:04

Community

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1

answered Apr 10 '10 at 10:17

Itay Maman

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10

-1 for just posting a copy and paste solution for such an obvious homework assignment. – Bart Kiers Apr 10 '10 at 12:57
18

To downvoters: please read the guidelines: http://meta.stackexchange.com/questions/10811/how-to-ask-and-answer-homework-questions : "Don't downvote others who answer homework questions in good faith, even if they break these guidelines." – polygenelubricants Apr 10 '10 at 15:17
2

@polygenelubricants looks like most agree that this is an obvious homework question and the guidelines talk about non obvious ones. – josefx Jul 24 '10 at 13:55
2

for homework questions, it may be a good practice to include a bit of explanation so that it does not turn into Ctrl-C, Ctrl-V – CyprUS May 04 '12 at 12:23
charAt() and length() are String functions. – subhashis Jan 31 '15 at 03:32
As per given question,we should not use any type of predefined function. – pathe.kiran Jul 06 '17 at 16:51

score 8 · Answer 3 · answered Apr 10 '10 at 10:18

Well, printing itself would suggest a predefined function...

Presumably, though, you could obtain the characters and concatenate them manually in reverse (i.e. loop over it backwards). Of course, you could say concatenation is a predefined function... so maybe the char array itself. But again... why?

Is the source allowed to contain "egaugnal detatneiro tcejbo si avaj" ;-p

Also - note that string reversal is actually pretty complex if you consider unicode combining characters, surrogate pairs, etc. You should note the caveat that most string reversal mechanisms will only deal with the more common cases, but may struggle with i18n.

score 7 · Answer 4 · edited Sep 10 '15 at 15:00

7

String reverse(String s) {
  int legnth = s.length();
  char[] arrayCh = s.toCharArray();
  for(int i=0; i< length/2; i++) {
      char ch = s.charAt(i);
      arrayCh[i] = arrayCh[legnth-1-i];
      arrayCh[legnth-1-i] = ch;
  } 
 return new String(arrayCh);
}

edited Sep 10 '15 at 15:00

Lucky

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answered May 04 '12 at 11:12

Vijay Nalawade

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score 6 · Answer 5 · answered Apr 10 '10 at 10:20

6

How about a simple traverse from the end of the string to the beg:

void printRev(String str) {
 for(int i=str.length()-1;i>=0;i--)
  System.out.print(str.charAt(i));
}

answered Apr 10 '10 at 10:20

codaddict

445,704
82
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score 3 · Answer 6 · edited Feb 15 '13 at 19:17

3

public class StringReverse {

    public static void main(String[] args) {
        String s= (args[0]);
        for (int i =s.length()-1; i >= 0; i--) {            
               System.out.print(s.charAt(i));    
        }
    } 
}

Prints the reversed string of the input.

edited Feb 15 '13 at 19:17

Bo Persson

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answered Feb 15 '13 at 19:00

Tmf07

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score 3 · Answer 7 · edited Sep 10 '15 at 15:00

3

First of all: Why reinvent the wheel?

That being said: Loop from the length of the string to 0 and concatenate into another string.

edited Sep 10 '15 at 15:00

Lucky

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answered Apr 10 '10 at 10:16

Paulo Santos

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score 3 · Answer 8 · edited Sep 10 '15 at 14:58

3

String a="Siva";

for(int i=0;i<=a.length()-1;i++){
    System.out.print(a.charAt(i));
}

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

edited Sep 10 '15 at 14:58

Lucky

16,787
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answered May 18 '11 at 06:05

user1138509

85
1
8

score 1 · Answer 9 · answered Jul 28 '12 at 20:46

public class StringReverse {
    public static void main(String ar[]){
        System.out.println(reverseMe("SRINIVAS"));
    }
    static String reverseMe(String s){
        StringBuffer sb=new StringBuffer();
        for(int i=s.length()-1;i>=0;--i){
            sb.append(s.charAt(i));
        }
        return sb.toString();
    }
}

score 1 · Answer 10 · edited Aug 02 '12 at 18:39

1

private void rev() {
    String st="hello";
    String b="";

    for(int i=st.length()-1;i>=0;i--){
        b=b+st.charAt(i);
    }

    System.out.println("reverse:::"+b);
}

edited Aug 02 '12 at 18:39

nhahtdh

55,989
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answered Aug 02 '12 at 14:58

praveen

11
1

score 1 · Answer 11 · edited Aug 16 '13 at 06:23

1

Try this:

public  class Test {

    public static void main(String[] args) {
        String s = "welcome";   
    for( int i=0, j = (s.length())-1; i <= j; j-- ) {   
      char c=s.charAt(j);
      System.out.print(c);
    }
    }
}

edited Aug 16 '13 at 06:23

Anshu Dwibhashi

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answered Aug 16 '13 at 06:05

hussinbasha

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1

score 1 · Answer 12 · answered Aug 16 '13 at 06:38

1

What is suprising is that most of the answers are wrong! When Unicode is used. Seems like no one understands that java uses UTF-16 under the hood for Text encoding.

Here is my simple answer.

static String reverseMe(String s) {
   StringBuilder sb = new StringBuilder();

   int count = s.codePointCount(0,s.length());
   for(int i = count - 1; i >= 0; --i)
     sb.append(Character.toChars(s.codePointAt(i)));

   return sb.toString();
 }

answered Aug 16 '13 at 06:38

Chad

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Similar solution using `java.text.BreakIterator`: http://stackoverflow.com/a/20279110/9636 – Heath Borders Nov 29 '13 at 05:45
Thanks Heath Borders. I didn't really go in Precomposed character (I don't think most people know what they're). In the above it no doubt will break reversing a string that used them. – Chad Dec 02 '13 at 05:38

score 1 · Answer 13 · answered Jul 23 '14 at 04:14

1

this is the best solution for this

public class String_rev {
public static void main(String[] args) {
    String str="Karan Rajput";
    int ln=str.length();
    for (int i = ln; i > 0; i--) {
        System.out.print(str.charAt(i-1));
    }
}

}

answered Jul 23 '14 at 04:14

Karan

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So many methods were already provided that does this method. I don't see how this can benefit when it is simply a derivative of the other posts. – rayryeng Jul 23 '14 at 04:46

score 1 · Answer 14 · answered Apr 10 '10 at 15:23

Here's a recursive solution that just prints the string in reverse order. It should be educational if you're trying to learn recursion. I've also made it "wrong" by actually having 2 print statements; one of them should be commented out. Try to figure out which mentally, or just run experiments. Either way, learn from it.

static void printReverse(String s) {
    if (!s.isEmpty()) {
        System.out.print(s.substring(0, 1));
        printReverse(s.substring(1));
        System.out.print(s.substring(0, 1));
    }
}

Bonus points if you answer these questions:

What is its stack requirement? Is it prone to stack overflow?
Is it a tail recursion?

score 1 · Answer 15 · edited Sep 17 '11 at 14:00

final String s = "123456789";
final char[] word = s.toCharArray();
final int l = s.length() - 2;
final int ll = s.length() - 1;
for (int i = 0; i < l; i++) {
    char x = word[i];
    word[i] = word[ll - i];
    word[ll - i] = x;
}
System.out.println(s);
System.out.println(new String(word));

You can do it either recursively or iteratively (looping).

Iteratively:

static String reverseMe(String s) {
    StringBuilder sb = new StringBuilder();
    for (int i = s.length() - 1; i >= 0; --i)
        sb.append(s.charAt(i));
    return sb.toString();
}

Recursively:

static String reverseMe(String s) {
    if (s.length() == 0)
        return "";
    return s.charAt(s.length() - 1) + reverseMe(s.substring(1));
}

Integer i = new Integer(15);
test(i);
System.out.println(i);
test(i);
System.out.println(i); 
public static void test (Integer i) {
    i = (Integer)i + 10;
}

return s.charAt(s.length() - 1) + reverseMe(s.substring(1)); is wrong instead it should be return s.charAt(s.length() - 1) + reverseMe(s.substring(0,s.length())); — Atul Singh Rathore, Sep 20 '20 at 20:56

score 0 · Answer 16 · edited Apr 13 '12 at 12:19

0

public class ReverseString {

public static void main(String [] args) {

    String s = "reverse string" ;
    String b = "";

            for (int i = 0; i < s.length(); i++ ){
                 b= b + s.substring(s.length()-1-i, s.length()-i);

                 }

             System.out.println(b);
}

edited Apr 13 '12 at 12:19

antyrat

27,479
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answered Apr 13 '12 at 11:27

neeraj bhadouria

1

easiest way to do it without using any specific method. – neeraj bhadouria Apr 13 '12 at 11:28
1

Welcome to stackoverflow. That is very similar to previous suggestions. Given the age of this thread, it is best not to resurrect it unless the response contributes something significantly different than previous answers. – Leigh Apr 14 '12 at 06:58

score 0 · Answer 17 · edited Apr 10 '13 at 16:37

import java.util.*;
public class Restring {

public static void main(String[] args) {
  String input,output;
  Scanner kbd=new Scanner(System.in);
  System.out.println("Please Enter a String");
  input=kbd.nextLine();
  int n=input.length();

  char tmp[]=new char[n];
  char nxt[]=new char[n];

  tmp=input.toCharArray();
  int m=0;
  for(int i=n-1;i>=0;i--)
  {
      nxt[m]=tmp[i];
      m++;
  }

  System.out.print("Reversed String is   ");
  for(int i=0;i<n;i++)
  {
      System.out.print(nxt[i]);
  }

}

score 0 · Answer 18 · edited Apr 10 '13 at 16:37

0

public String reverse(String arg)
{
    String tmp = null;
    if (arg.length() == 1)
    {
        return arg;
    }

    else
    {

        String lastChar = arg.substring(arg.length()-1,arg.length());

        String remainingString = arg.substring(0, arg.length() -1);

        tmp = lastChar + reverse(remainingString);
        return tmp;


    }
}

edited Apr 10 '13 at 16:37

Bo Persson

90,663
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answered Feb 28 '13 at 09:57

Ambreen

11
1

srk · Answer 19 · 2013-09-21T03:11:38.727

0

String x = "stack overflow";
String reversed = "";
for(int i = x.length()-1 ; i>=0; i--){
    reversed = reversed+ x.charAt(i);
}
System.out.println("reversed string is : "+ reversed);

edited Sep 21 '13 at 03:11

answered Apr 05 '13 at 13:53

srk

4,857
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score 0 · Answer 20 · edited Apr 10 '13 at 16:35

public static void main(String[] args) {


    String str = "hello world here I am";

    StringTokenizer strToken = new StringTokenizer(str);
    int token = strToken.countTokens();
    String str1 [] = new String[token];

    char chr[] = new char[str.length()];
    int counter = 0;

    for(int j=0; j < str.length(); j++) {

        if(str.charAt(j) != ' ') {
            chr[j] = str.charAt(j);
        }else {
            str1[counter++] = new String(chr).trim();
            chr = new char[str.length()];
        }
    }
    str1[counter++] = new String(chr).trim();

    for(int i=str1.length-1; i >= 0 ; i--) {
        System.out.println(str1[i]);
    }
}

O/P is: am I here world hello

score 0 · Answer 21 · answered Jul 09 '13 at 06:02

 public class ReverseWithoutStringAPI {

public static void main(String[] args) {

      String st="hello";

        StringBuffer b=new StringBuffer();

        for(int i=st.length()-1;i>=0;i--){

            b.append(st.charAt(i)); }

        System.out.println("reverse:::"+b);
}
}

score 0 · Answer 22 · answered Apr 29 '14 at 14:13

Here you go:

public static void main (String[] args) {
    System.out.println(reverserString("Akshay"));
}

private static String reverserString(String src) {
    char[] sArr = src.toCharArray();
    char[] dArr = new char[sArr.length];
    for(int i=sArr.length; i>0; i--) {
        dArr[sArr.length-i] = sArr[i-1];
    }

    return new String(dArr);
}

score 0 · Answer 23 · answered Jun 18 '14 at 12:01

public class MyStack {
   private int maxSize;
   private char[] stackArray;
   private int top;
   public MyStack(int s) {
      maxSize = s;
      stackArray = new char[maxSize];
      top = -1;
   }
   public void push(char j) {
      stackArray[++top] = j;
   }
   public char pop() {
      return stackArray[top--];
   }
   public char peek() {
      return stackArray[top];
   }
   public boolean isEmpty() {
      return (top == -1);
   }
   public boolean isFull() {
      return (top == maxSize - 1);
   }
   public static void main(String[] args) {
      MyStack theStack = new MyStack(10);
      String s="abcd";
      for(int i=0;i<s.length();i++)
      theStack.push(s.charAt(i));
      for(int i=0;i<s.length();i++)
      System.out.println(theStack.pop());

    }

score 0 · Answer 24 · edited Oct 03 '17 at 07:02

0

Code will be as below:

public class RemoveString {

public static void main(String[] args) {

Scanner scanner=new Scanner(System.in);

String s=scanner.next();

String st="";

for(int i=s.length()-1;i>=0;i--){

st=st+s.charAt(i);


}

System.out.println(st);

}

}

edited Oct 03 '17 at 07:02

Shubham Jain

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answered Jun 25 '14 at 17:07

BONDbATIF

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subhashis · Answer 25 · 2015-01-31T04:16:54.883

0

public class ReverseString {

public static void main(String[] args) {

    reverseString("HELLO");
}

public static String reverseString(String s){
    char []arr=s.toCharArray();
    for(int i= (arr.length)-1;i>=0;i--){
        System.out.print(arr[i]);
    }
    String str=String.copyValueOf(arr);
    return str;
}

edited Jan 31 '15 at 04:16

answered Jan 31 '15 at 03:43

subhashis

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score 0 · Answer 26 · edited Oct 03 '17 at 07:01

0

Code will be as below:

   public class A{
       public static void main(String args[]){

      String str="hello";
      for(int i=str.length()-1;i>=0;i--){
        String str1=str.charAt(i);
        system.out.print(str1);
      }

   }
}

edited Oct 03 '17 at 07:01

Shubham Jain

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answered Feb 16 '15 at 14:11

shaik sajid

1

You might want to describe what makes this answer correct. – rfornal Feb 16 '15 at 14:32

score 0 · Answer 27 · edited Apr 27 '15 at 13:24

package com.ofs;

public class ReverseWordsInString{
public static void main(String[] args) {

    String str = "welcome to the new world and how are you feeling ?";

    // Get the Java runtime
    Runtime runtime = Runtime.getRuntime();
    // Run the garbage collector
    runtime.gc();
    // Calculate the used memory
    long firstUsageMemory = runtime.totalMemory() - runtime.freeMemory();
    System.out.println("Used memory in bytes: " + firstUsageMemory);
    System.out.println(str);
    str = new StringBuffer(str).reverse().toString();
    int count = 0;
    int preValue = 0;
    int lastspaceIndexVal = str.lastIndexOf(" ");
    int strLen = str.length();
    for (int i = 0; i < strLen - 1; i++) {
        if (Character.isWhitespace(str.charAt(i))) {
            if (i - preValue == 1 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 2 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 3 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 4 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 5 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.substring(i - 2, i - 1) + str.charAt(i - 3)
                        + str.charAt(i - 3) + str.charAt(i - 5)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 6 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.charAt(i - 6) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 7 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.charAt(i - 6) + str.charAt(i - 7)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 8 && count == 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.charAt(i - 6) + str.charAt(i - 7)
                        + str.charAt(i - 8) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 2 && count != 0) {
                str = str.substring(0, preValue) + str.charAt(i - 1)
                        + str.substring(i, strLen);
                preValue = i;
            } else if (i - preValue == 3 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.substring(i, strLen);
                preValue = i;
            } else if (i - preValue == 4 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.substring(i, strLen);
                preValue = i;
            } else if (i - preValue == 5 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 6 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 7 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.charAt(i - 6) + str.substring(i, strLen);
                preValue = i;
                count++;
            } else if (i - preValue == 8 && count != 0) {
                str = str.substring(0, preValue + 1) + str.charAt(i - 1)
                        + str.charAt(i - 2) + str.charAt(i - 3)
                        + str.charAt(i - 4) + str.charAt(i - 5)
                        + str.charAt(i - 6) + str.charAt(i - 7)
                        + str.substring(i, strLen);
                preValue = i;
                count++;
            }
            if (lastspaceIndexVal == preValue) {
                if (strLen - lastspaceIndexVal == 2 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1);
                    preValue = i;
                } else if (strLen - lastspaceIndexVal == 3 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2);
                    preValue = i;
                } else if (strLen - lastspaceIndexVal == 4 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2)
                            + str.charAt(strLen - 3);
                    preValue = i;
                    count++;
                } else if (strLen - lastspaceIndexVal == 5 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2)
                            + str.charAt(strLen - 3)
                            + str.charAt(strLen - 4);
                    preValue = i;
                } else if (strLen - lastspaceIndexVal == 6 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2)
                            + str.charAt(strLen - 3)
                            + str.charAt(strLen - 4)
                            + str.charAt(strLen - 5);
                    preValue = i;
                    count++;
                } else if (strLen - lastspaceIndexVal == 7 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2)
                            + str.charAt(strLen - 3)
                            + str.charAt(strLen - 4)
                            + str.charAt(strLen - 5)
                            + str.charAt(strLen - 6);
                    preValue = i;
                } else if (strLen - lastspaceIndexVal == 8 && count != 0) {
                    str = str.substring(0, preValue + 1)
                            + str.charAt(strLen - 1)
                            + str.charAt(strLen - 2)
                            + str.charAt(strLen - 3)
                            + str.charAt(strLen - 4)
                            + str.charAt(strLen - 5)
                            + str.charAt(strLen - 6)
                            + str.charAt(strLen - 7);
                    preValue = i;
                }
            }
        }
    }
    runtime.gc();
    // Calculate the used memory
    long SecondaryUsageMemory = runtime.totalMemory()
            - runtime.freeMemory();
    System.out.println("Used memory in bytes: " + SecondaryUsageMemory);
    System.out.println(str);
}
}

score 0 · Answer 28 · answered May 15 '15 at 03:36

ReverseString.java

public class ReverseString {
    public static void main(String[] args) {
        String str = "Ranga Reddy";
        String revStr = reverseStr(str);
        System.out.println(revStr);     
    }

    // Way1 - Recursive
    public static String reverseStr(String str) {
        char arrStr[] = reverseString(0, str.toCharArray());
        return new String(arrStr);
    }

    private static char[] reverseString(int charIndex, char[] arr) {     
        if (charIndex > arr.length - (charIndex+1)) {
          return arr;
        }

        int startIndex = charIndex;
        int endIndex = arr.length - (charIndex+1);

        char temp = arr[startIndex];        
        arr[startIndex] = arr[endIndex];
        arr[endIndex] = temp;      
        charIndex++;       
        return reverseString(charIndex++, arr);
    }

    // Way2
    private static String strReverse(String str) {
        char ch[] = new char[str.length()];
        for (int i = str.length() - 1, j = 0; i >= 0; i--) {
            ch[j++] = str.charAt(i);
        }
        return new String(ch);
    }
}

score 0 · Answer 29 · answered Jun 23 '15 at 09:45

It is very simple using while loop

public class Test {
public static void main(String[] args) {
    String name = "subha chandra";
    int len = name.length();
    while(len > 0){
        len--;
        char c = name.charAt(len);
        System.out.print(c); // use String.valueOf(c) to convert char to String
    }
}    
}

Manash Ranjan Dakua · Answer 30 · 2015-10-01T16:21:05.137

import java.util.Scanner;
public class StringReverse {
    public static void main(String[] args) {
        //Read user Data From Console
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter Your String:");
        //Take an String so that it can Store the string data 
        String s1 = sc.nextLine();
        //split the string and keep in an array
        String[] s2 = s1.split(" ");
        String s3 = " ";
        //reverse  the string and placed in an String s3
        for (int i = 0; i < s2.length; i++) {
            for (int j= s2[i].length()-1;j>=0;j--) {
                s3 += s2[i].charAt(j);
            }//for
            s3 += " ";
        }//for

        System.out.println("After Reverse: "+s3);

    }//main
}//StringReverse

DistributedAI · Answer 31 · 2015-12-10T13:22:45.653

0

It can be done this way also

char c[]=str.toCharArray();
  int i=c.lenght-1;
public void printReverseString(char[] c, int i){
       if(i==-1) return;
       System.out.println(c[i]);
       printReverseString(c,--i);
   }

edited Dec 10 '15 at 13:22

answered Dec 10 '15 at 13:13

DistributedAI

193
1
9

score 0 · Answer 32 · answered May 28 '18 at 12:42

You can simply try like this take a string iterate over it using for loop till second last character of string and then simply reverse your loop like following:

public class StringReverse {
    public static void main(String ar[]){
        System.out.println(reverseMe("iniana"));
    }
    static String reverseMe(String s){
       String reverse = "";
       for(int i = s.length()-1; i>=0; i--){
           resverse = reverse + s.charAt(i);
       }
       return reverse;
    }
}

score 0 · Answer 33 · edited Apr 10 '13 at 16:36

I had this a while back, and having answered with the obvious StringBuffer.reverse() answer, they then asked 'Can you reverse a char array without using those API methods and achieve the result without spooling into a new char array?'

At the time I recognised that I only needed to iterate over half the length of the char array, but made a bit of a hash of explaining the actual code that needed to go into it (it was a verbal question). Anyway, I tried it when I got home and came up with this:

public class StringReverse {

public static void main(String[] args){

    String a = "String";

    char[] aChar = a.toCharArray();

    for (int i = (aChar.length-1)/2 ; i >= 0 ; i--){
        int posA = i;
        int posB = (aChar.length-1-i);
        char tmpA = aChar[posA];
        char tmpB = aChar[posB];
        System.out.println("Setting " + posA + " to " + tmpB);
        System.out.println("Setting " + posB + " to " + tmpA);

        aChar[posA] = tmpB;
        aChar[posB] = tmpA;
    }

    System.out.println(aChar);
}

}

You can obviously achieve this with less code, but I think the temporary assignments in the method make it more clear what the code is doing.

Outputs something like:

Setting 2 to i
Setting 3 to r
Setting 1 to n
Setting 4 to t
Setting 0 to g
Setting 5 to S

gnirtS

More of an interview question than a homework question, I'd say.

score -1 · Answer 34 · edited Mar 31 '15 at 14:10

public class Match {
 void comp(String s1, String s2) {
    char[] charArray1 = s1.toCharArray();
    char[] charArray2 = s2.toCharArray();

    int length1 = charArray1.length;        

    int length2 = charArray2.length;       
    int flag = 0;

    if (length1 == length2) {
        for (int i = 0; i <= length1 - 1; i++) {
            if (charArray1[i] == charArray2[i]) {
                System.out.println("index are matched:" + " " + charArray1[i] + " " + "in index-" + i);

            } else {
                flag = 1;
                System.out.println("index are not matched:" + " " + charArray1[i] + " " + "in index-" + i);
                System.out.println("index are not matched:" + " " + charArray2[i] + " " + "in index-" + i);                    
            }
        }
    } else {
        System.out.println("Your string are not matched by length");
    }
    if (flag == 0) {
        System.out.println("Your string  matched with other String");
    } else {
        System.out.println("Your string are not matched");
    }
}
public static void main(String[] args) {
    java.util.Scanner sc = new java.util.Scanner(System.in);
    System.out.println("Enter the 1st String:");
    String s1 = sc.nextLine();
    System.out.println("Enter the 2nd string");
    String s2 = sc.nextLine();
    Match m = new Match();
    m.comp(s1, s2);
}
}

While this answer is probably correct and useful, it is preferred if you [include some explanation along with it](http://meta.stackexchange.com/q/114762/159034) to explain how it helps to solve the problem. This becomes especially useful in the future, if there is a change (possibly unrelated) that causes it to stop working and users need to understand how it once worked. — Kevin Brown-Silva, Aug 22 '15 at 17:56

Printing reverse of any String without using any predefined function?

34 Answers34

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