how to create dynamic two dimensional array in java

Question

I want to create a two dimensional array dynamically   I know the number of columns  But the number of rows are being changed dynamically  I tried the array list  but it stores the value in single dimension only  What can I do

User · Answer

Here is a simple example  this method will return a 2 dimensional tType array  public tType     allocate Class lt tType gt  c int row int column           tType      matrix    tType      Array newInstance c row           for  int i   0  i  lt  column  i                  matrix i     tType    Array newInstance c column                     return matrix           say you want a 2 dimensional String array  then call this function as  String      stringArray   allocate String class 3 3     This will give you a two dimensional String array with 3 rows and 3 columns  Note that in Class lt tType gt  c -  c cannot be primitive type like say  int or char or double  It must be non-primitive like  String or Double or Integer and so on

User · Answer

How about making a custom class containing an array  and use the array of your custom class

User · Answer

List lt Integer gt    array    array   new List lt Integer gt  10     this the second case in  TofuBeer s answer is incorrect  because can t create arrays with generics  u can use  List lt List lt Integer gt  gt  array   new ArrayList lt  gt

User · Answer

Try to make Treemap  lt  Integer  Treemap lt Integer  obj gt   gt   In java  Treemap is sorted map  And the number of item in row and col wont screw the 2D-index you want to set  Then you can get a col-row table like structure

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Scanner sc new Scanner System in    int p       new int n      for int i 0   i lt n   i          int m   sc nextInt            Taking input from user in JAVA      p i  new int m            Allocating memory block of  m  int size block       for int j 0   j lt m   j                   p i  j  sc nextInt        Initializing 2D array block

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simple you want to inialize a 2d array and assign a size of array then  a example is      public static void main String args              char arr          arr is 2d array name     arr   new char 3  3                 this is a way to inialize a 2d array in java

User · Answer

There are no multi-dimensional arrays in Java  there are  however  arrays of arrays   Just make an array of however large you want  then for each element make another array however large you want that one to be   int array       array   new int 10      array 0    new int 9   array 1    new int 8   array 2    new int 7   array 3    new int 6   array 4    new int 5   array 5    new int 4   array 6    new int 3   array 7    new int 2   array 8    new int 1   array 9    new int 0     Alternatively   List lt Integer gt    array   array   new List lt Integer gt  10       of you can do  new ArrayList lt Integer gt  the desired size    for all of the following array 0    new ArrayList lt Integer gt     array 1    new ArrayList lt Integer gt     array 2    new ArrayList lt Integer gt     array 3    new ArrayList lt Integer gt     array 4    new ArrayList lt Integer gt     array 5    new ArrayList lt Integer gt     array 6    new ArrayList lt Integer gt     array 7    new ArrayList lt Integer gt     array 8    new ArrayList lt Integer gt     array 9    new ArrayList lt Integer gt

User · Answer

One more example for 2 dimension String array   public void arrayExam         List lt String   gt  A   new ArrayList lt String   gt         A add new String     Jack   good         A add new String     Mary   better         A add new String     Kate   best         for  String   row   A            Log i TAG row 0     - gt     row 1              Output   17467 08-02 19 24 40 518  8456  8456 I MyExam    Jack- gt good 17468 08-02 19 24 40 518  8456  8456 I MyExam    Mary- gt better 17469 08-02 19 24 40 518  8456  8456 I MyExam    Kate- gt best

User · Answer

Since the number of columns is a constant  you can just have an List of int         import java util                   List lt int   gt  rowList   new ArrayList lt int   gt          rowList add new int     1  2  3         rowList add new int     4  5  6         rowList add new int     7  8          for  int   row   rowList            System out println  Row       Arrays toString row             prints           Row    1  2  3           Row    4  5  6           Row    7  8       System out println rowList get 1  1       prints  5    Since it s backed by a List  the number of rows can grow and shrink dynamically  Each row is backed by an int    which is static  but you said that the number of columns is fixed  so this is not a problem

[java] how to create dynamic two dimensional array in java?

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