Sorting an Array of int using BubbleSort

Question

Why is my printed out Array not sorted in the below code   public class BubbleSort       public void sortArray int   x     go through the array and sort from smallest to highest       for int i 1  i lt x length  i               int temp 0           if x i-1   gt  x i                 temp   x i-1               x i-1    x i               x i    temp                              public void printArray int   x          for int i 0  i lt x length  i            System out print x i                   public static void main String   args             TestBubbleSort       BubbleSort b   new BubbleSort          int   num    5 4 3 2 1         b sortArray num         b printArray num

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public class SortingArray   public static void main String   args     int   a  3 7 9 5 1 4 0 2 8 6   int temp 0   boolean isSwapped true    System out println   before sorting the array       for int i 0 i lt a length i          System out print a i      System out println       do    isSwapped false   for int i 0 i lt a length-1 i            if a i  gt a i 1                   temp a i            a i  a i 1            a i 1  temp                 while isSwapped     System out println  after sorting the array           for int array a                  System out print array

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public static void BubbleSort int   array           boolean swapped           do               swapped   false              for  int i   0  i  lt  array length - 1  i                      if  array i   gt  array i   1                         int temp   array i                       array i    array i   1                       array i   1    temp                      swapped   true                                           while  swapped

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java code      public void bubbleSort int   arr           boolean isSwapped   true       for int i   arr length - 1  isSwapped  i--            isSwapped   false           for int j   0  j  lt  i  j                  if arr j   gt  arr j 1                    int temp   arr j                   arr j    arr j 1                   arr j 1    temp                  isSwapped   true

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Bubble sort algorithm is a simplest way of sorting array elements Most of another algorithms are more efficient than bubble sort algorithm  Worst case and average case time complexity is  n 2  Let s consider how to implement bubble sort algorithm   class buble sort    public static void main String a          int   num  7 9 2 4 5 6 3       int i j tmp       for i 0 i lt num length i             for j 0 j lt num length-i j                 if j   num length-1                    break                            else                  if num j  gt num j 1                        tmp num j                       num j  num j 1                       num j 1  tmp                                                       for i 0 i lt num length i             System out print num i

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Standard Bubble Sort implementation in Java     Time complexity  O n 2  public static int   bubbleSort int   arr         if  arr    null    arr length  lt   1            return arr             for  int i   0  i  lt  arr length  i              for  int j   1  j  lt  arr length - i  j                  if  arr j - 1   gt  arr j                     arr j    arr j    arr j - 1                   arr j - 1    arr j  - arr j - 1                   arr j    arr j  - arr j - 1                                      return arr

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I use this method for bubble sorting  public static int   bubbleSort  int   a        int n   a length      int j   0      boolean swap   true      while  swap            swap   false          for  int j   1  j  lt  n  j                  if  a j-1   gt  a j                     j   a j-1                   a j-1    a j                   a j    j                  swap   true                                  n   n - 1            return a     end bubbleSort

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This isn t the bubble sort algorithm  you need to repeat until you have nothing to swap    public void sortArray int   x     go through the array and sort from smallest to highest   for             boolean s   false        for int i 1  i lt x length  i               int temp 0           if x i-1   gt  x i                 temp   x i-1               x i-1    x i               x i    temp              s   true                           if   s  return

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public class Bubblesort     public static int arr       public static void main String args          System out println  Enter number of element you have in array for performing bubblesort         int numbofele   Integer parseInt args 0         System out println  numer of element entered is     n    numbofele        arr  new int numbofele        System out println  Enter Elements of array         System out println  The given array is          for int i 0 j 1 i lt numbofele i   j            arr i  Integer parseInt args j           System out println arr i                boolean swapped   false       System out println  The sorted array is         for int k 0 k lt numbofele-1 k             for int l 0 l 1 lt numbofele-k l              if arr l  gt arr l 1               int temp   arr l             arr l   arr l 1             arr l 1  temp            swapped true                                 if  swapped                for int m 0 m lt numbofele m             System out println arr m                  return                        for int m 0 m lt numbofele m             System out println arr m

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Really not getting the bubble sort  which can be called a sinking sort more appropriately since it s actually sinking the bigger heavier to the bottom as the majority of the answers presented  One of the most typicals will be  private static void sortZero Comparable   arr        boolean moreSinkingRequired   true      while  moreSinkingRequired            moreSinkingRequired   false          for  int j   0  j  lt  arr length - 1    j                if  less arr  j   1  j                      exch arr  j  j   1                   moreSinkingRequired   true                                    By the way  you have to traverse once more than actually required to stop earlier    But as I see it bubbling as  private static void sortOne Comparable   arr        for  int i   0  i  lt  arr length - 1    i            for  int j   arr length - 1  j  gt  i  --j       start from the bottom             if  less arr  j  j - 1                     exch arr  j - 1  j                                     You have to know this method is actually better since it s tracking the end point for comparison by j  gt  i with  0  i-1  already sorted    We also can add earlier termination but it then becomes verbose as  private static void sortTwo Comparable   arr        boolean moreBubbleRequired   true      for  int i   0  i  lt  arr length - 1  amp  amp  moreBubbleRequired    i            moreBubbleRequired   false          for  int j   arr length - 1  j  gt  i  --j                if  less arr  j  j - 1                     exch arr  j - 1  j                   moreBubbleRequired   true                                      The utils used to make the process terse are  public static boolean less Comparable   arr  int i  int j        return less arr i   arr j       public static boolean less Comparable a  Comparable b        return a compareTo b   lt  0     public static void exch Comparable   arr  int i  int j        Comparable t   arr i       arr i    arr j       arr j    t

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Your sort logic is wrong   This is the pseudo-code for bubble sort   for i   1 n      swapped   false     for j   n i 1           if a j   lt  a j-1                swap a j j-1              swapped   true       invariant  a 1  i  in final position     break if not swapped end   See this sorting web site for good tutorial on all the various sorting methods

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Here is an example of bubbleSort  and Time Complexity is O n     int   bubbleSort int   numbers            if numbers    null    numbers length    1                return numbers                     boolean isSorted   false           while  isSorted                isSorted   true              for int i   0  i  lt  numbers length - 1  i                      if numbers i   gt  numbers i   1                         int hold   numbers i   1                       numbers i   1    numbers i                       numbers i    hold                      isSorted   false                                                     return numbers

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Here we go  static String arrayToString int   array        StringBuilder stringBuilder   new StringBuilder        for  int i   0  i  lt  array length  i            stringBuilder append array i   append                 return stringBuilder deleteCharAt stringBuilder length  -1  toString           public static void main String    args       int   unsorted    9 2 1 4 0       System out println  Sorting an array of Length   unsorted length       enhancedBubbleSort unsorted         dumbBubbleSort unsorted         bubbleSort unsorted         enhancedBubbleSort unsorted         enhancedBubbleSortBetterStructured unsorted       System out println  Sorted Array    arrayToString unsorted               this is the dumbest BubbleSort   static int   dumbBubbleSort int   array       for  int i   0  i lt array length-1   i            for  int j   0  j  lt  array length - 1  j              if  array j   gt  array j   1                  Just swap           int temp   array j             array j    array j   1             array j   1    temp                          System out println  After    i 1    pass    arrayToString array              return array           this  -i  in array length - 1-i brings some improvement       Then for making our bestcase scenario better   o n    we will introduce isswapped flag  that s enhanced bubble sort    static int   bubbleSort int   array       for  int i   0  i lt array length-1   i            for  int j   0  j  lt  array length - 1-i  j              if  array j   gt  array j   1               int temp   array j             array j    array j   1             array j   1    temp                          System out println  After    i 1    pass    arrayToString array              return array         static int   enhancedBubbleSort int   array       int i 0      while  true          boolean swapped   false        for  int j   0  j  lt  array length - 1  j              if  array j   gt  array j   1               int temp   array j             array j    array j   1             array j   1    temp            swapped  true                          i          System out println  After    i    pass    arrayToString array          if  swapped              Last iteration  of outer loop  didnot result in any swaps  so stopping here         break                    return array         static int   enhancedBubbleSortBetterStructured int   array       int i 0      boolean swapped   true      while  swapped          swapped   false        for  int j   0  j  lt  array length - 1  j              if  array j   gt  array j   1               int temp   array j             array j    array j   1             array j   1    temp            swapped   true                          i          System out println  After    i    pass    arrayToString array              return array

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Bubble sort nested loops should be written like this   int n   intArray length  int temp   0   for int i 0  i  lt  n  i        for int j 1  j  lt   n-i   j                                    if intArray j-1   gt  intArray j                  swap the elements              temp   intArray j-1               intArray j-1    intArray j               intArray j    temp

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You need two loops to implement the Bubble Sort    Sample code    public static void bubbleSort int   numArray         int n   numArray length      int temp   0       for  int i   0  i  lt  n  i              for  int j   1  j  lt   n - i   j                   if  numArray j - 1   gt  numArray j                     temp   numArray j - 1                   numArray j - 1    numArray j                   numArray j    temp

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You re only making one pass through your array  Bubble sort requires you to keep looping until you find that you are no longer doing any swapping  hence the running time of O n 2    Try this   public void sortArray int   x        boolean swapped   true      while  swapped           swapped   false         for int i 1  i lt x length  i                 int temp 0             if x i-1   gt  x i                    temp   x i-1                   x i-1    x i                   x i    temp                  swapped   true                                    Once swapped    false at the end of a loop  you have made a whole pass without finding any instances where x i-1   gt  x i  and  hence  you know the array is sorted  Only then can you terminate the algorithm   You can also replace the outer while loop with a for loop of n 1 iterations  which will guarantee that the array is in order  however  the while loop has the advantage of early termination in a better-than-worst-case scenario

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public class BubbleSort        public void sorter int   arr  int x  int y                int temp   arr x               arr x    arr y               arr y    temp              public void sorter1 String   arr  int x  int y            String temp   arr x           arr x    arr y           arr y    temp              public void sertedArr int   a  String   b           for int j   0  j  lt  a length - 1  j                 for int i   0  i  lt  a length - 1  i                     if a i   gt  a i   1                        sorter a  i  i   1                       sorter1 b  i  i   1                                                     for int i   0  i  lt  a length  i                 System out print a i                      System out println            for int i   0  i  lt  b length  i                 System out print b i                                    public static void main String   args           int   array    3  7  4  9  5  6           String   name     t    a    b    m    2    3            BubbleSort bso   new BubbleSort                bso sertedArr array  name

[java] Sorting an Array of int using BubbleSort

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