How to swap String characters in Java

Question

How can I swap two characters in a String  For example   abcde  will become  bacde

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This has been answered a few times but here s one more just for fun  -   public class Tmp       public static void main String   args            System out println swapChars  abcde   0  1              private static String swapChars String str  int lIdx  int rIdx            StringBuilder sb   new StringBuilder str           char l   sb charAt lIdx   r   sb charAt rIdx           sb setCharAt lIdx  r           sb setCharAt rIdx  l           return sb toString

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The following line of code will swap the first two characters in str    return str charAt 1    str charAt 0    str substring 2

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String replaceAll   or replaceFirst    String s    abcde  replaceAll  ab    ba     Link to the JavaDocs String API

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static String  string swap String str  int x  int y         if  x  lt  0    x  gt   str length      y  lt  0    y  gt   str length        return  Invalid index        char arr     str toCharArray        char tmp   arr x       arr x    arr y       arr y    tmp       return new String arr

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Here is java sample code for swapping java chars recursively   You can get full sample code at http   java2novice com java-interview-programs string-reverse-recursive   public String reverseString String str        if str length      1           return str        else           reverse    str charAt str length  -1                   reverseString str substring 0 str length  -1            return reverse

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StringBuilder sb   new StringBuilder  quot abcde quot    sb setCharAt 0   b    sb setCharAt 1   a    String newString   sb toString

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Here s a solution with a StringBuilder  It supports padding resulting strings with uneven string length with a padding character  As you ve guessed this method is made for hexadecimal-nibble-swapping          Swaps every character at position i with the character at position i   1 in the given    string      public static String swapCharacters final String value  final boolean padding       if   value    null              return null           final StringBuilder stringBuilder   new StringBuilder       int posA   0     int posB   1     final char padChar    F          swap characters    while   posA  lt  value length    amp  amp  posB  lt  value length                stringBuilder append  value charAt  posB     append  value charAt  posA            posA    2        posB    2              if resulting string is still smaller than original string we missed the last       character    if   stringBuilder length    lt  value length                stringBuilder append  value charAt  posA                  add the padding character for uneven strings    if   padding  amp  amp  value length     2    0              stringBuilder append  padChar             return stringBuilder toString

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public static String shuffle String s        List lt String gt  letters   Arrays asList s split           Collections shuffle letters       StringBuilder t   new StringBuilder s length         for  String k   letters            t append k             return t toString

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this is a very basic way of how to order a string alpha-wise  this does not use anything fancy and is great for school use  package string sorter   public class String Sorter                    param args the command line arguments             public static void main String   args             String word    quot jihgfedcba quot           for  int endOfString   word length    endOfString  gt  0  endOfString--                 int largestWord   word charAt 0               int location   0              for  int index   0  index  lt  endOfString  index                       if  word charAt index   gt  largestWord                         largestWord   word charAt index                       location   index                                               if  location  lt  endOfString - 1                     String newString   word substring 0  location    word charAt endOfString - 1    word substring location   1  endOfString - 1    word charAt location                   word   newString                            System out println word                      System out println word

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Since String objects are immutable  going to a char   via toCharArray  swapping the characters  then making a new String from char   via the String char    constructor would work   The following example swaps the first and second characters   String originalString    abcde    char   c   originalString toCharArray        Replace with a  swap  function  if desired  char temp   c 0   c 0    c 1   c 1    temp   String swappedString   new String c    System out println originalString   System out println swappedString     Result   abcde bacde

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In  a string  you cant  Strings are immutable  You can easily create a second string with    String second   first replaceFirst             2 1

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I think this should help   import java util     public class StringSwap   public static void main String ar         Scanner in   new Scanner System in       String s   in next        System out println new StringBuffer s substring 0 2   reverse   toString   concat s substring 2

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s   s substring 0  firstChar               s charAt secondChar               s substring firstChar   1  secondChar               s charAt firstChar               s substring secondChar 1

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String toCharArray   will give you an array of characters representing this string   You can change this without changing the original string  swap any characters you require   and then create a new string using String char      Note that strings are immutable  so you have to create a new string object

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import java io    class swaping        public static void main String args                     String name  premkumarg            int len name length             char   c   name toCharArray             for int i 0 i lt len-1 i i 2                          char temp  c i                c i  c i 1                c i 1  temp                       System out println  Swapping string is               System out println c

[java] How to swap String characters in Java?

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