java Arrays sort 2d array

Question

I am looking to sort the following array based on the values of    0  double     myArr   new double mySize  2    so for example  myArr contents is  1      5 13     1 55 12     100 6 12 1    85  I want it to get to  1      5 12     100 6 12 1    85 13     1 55  I am looking to do this without having to implement my own sort

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for decreasing order for integer array of 2 dimension you can use  Arrays sort contests   a  b  - gt  Integer compare b 0  a 0      decreasing order  Arrays sort contests   a  b  - gt  Integer compare a 0  b 0     decreasing order

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Although this is an old thread  here are two examples for solving the problem in Java8   sorting by the first column     0      double     myArr   new double mySize  2          java util Arrays sort myArr  java util Comparator comparingDouble a - gt  a 0       sorting by the first two columns     0      1     double     myArr   new double mySize  2          java util Arrays sort myArr  java util Comparator  lt double   gt comparingDouble a - gt  a 0   thenComparingDouble a - gt  a 1

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Use Overloaded Arrays Sort T   a  Comparator c  which takes Comparator as the second argument   double     array     1  5    13  1 55    12  100 6    12 1   85      java util Arrays sort array  new java util Comparator lt double   gt          public int compare double   a  double   b            return Double compare a 0   b 0                JAVA-8  Instead of that big comparator  we can use lambda function as following-   Arrays sort array  Comparator comparingDouble o - gt  o 0

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Java 8 is now very common nowadays   Arrays sort myArr  double   a double   b - gt                     here multiple lines of code can be placed                 return a 0 -b 0

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import java util     public class Arrays2       public static void main String   args                int small  row   0  col   0  z          int     array   new int 5  5            Random rand   new Random            for int i   0  i  lt  array length  i                          for int j   0  j  lt  array i  length  j                                  array i  j    rand nextInt 100                   System out print array i  j                                    System out println                       System out println   n              for int k   0  k  lt  array length  k                          for int p   0  p  lt  array k  length  p                                  small   array k  p                   for int i   k  i  lt  array length  i                                          if i    k                          z   p   1                      else                         z   0                      for  z  lt  array i  length  z                                                  if array i  z   lt   small                                                        small   array i  z                               row   i                              col   z                                                                                array row  col    array k  p               array k  p    small              System out print array k  p                                    System out println                        Good Luck

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For a general solution you can use the Column Comparator  The code to use the class would be   Arrays sort myArr  new ColumnComparator 0

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To sort in descending order you can flip the two parameters int     array         1  5        13  1        12  100        12  85      Arrays sort array   b  a  - gt  Integer compare a 0   b 0      Output  13  5 12  100 12  85 1  5

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The simplest way   Arrays sort myArr   a  b  - gt  a 0  - b 0

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You need to implement a Comparator lt Double   gt  like so   public static void main String   args  throws IOException       final Double     doubles   new Double      5 0  4 0    1 0  1 0    4 0  6 0        final Comparator lt Double   gt  arrayComparator   new Comparator lt Double   gt               Override         public int compare Double   o1  Double   o2                return o1 0  compareTo o2 0                         Arrays sort doubles  arrayComparator       for  final Double   arr   doubles            System out println Arrays toString arr              Output    1 0  1 0   4 0  6 0   5 0  4 0

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Simplified Java 8  IntelliJ suggests to simplify the top answer to the   Arrays sort queries  Comparator comparingDouble a - gt  a 0

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It is really simple  there are just some syntax you have to keep in mind  Arrays sort contests   a  b  - gt  Integer compare a 0  b 0      increasing order     ---1 Arrays sort contests   b  a  - gt  Integer compare b 0  a 0      increasing order     ---2 Arrays sort contests   a  b  - gt  Integer compare b 0  a 0      decreasing order     ---3 Arrays sort contests   b  a  - gt  Integer compare a 0  b 0      decreasing order     ---4 If you notice carefully  then it s the change in the order of  a  and  b  that affects the result  For line 1  the set is of  a b  and Integer compare a 0  b 0    so it is increasing order  Now if we change the order of a and b in any one of them  suppose the set of  a b  and Integer compare b 0  a 0   as in line 3  we get decreasing order

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Welcome Java 8   Arrays sort myArr   a  b  - gt  Double compare a 0   b 0

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much simpler code  import java util Arrays  int     array   new int      Arrays sort array    a   b  - gt  a 1  - b 1

[java] java Arrays.sort 2d array

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