Two dimensional array list

Question

I ve heard of using a two dimensional array like this    String     strArr    But is there any way of doing this with a list   Maybe something like this   ArrayList lt String gt  lt String gt  strList    And using something like this to add to it   strList add  hey    hey      Any way of doing something like this  Any help appreciated   It would be good if there is because i am currently putting strings into two differrent ArrayList s in pairs

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You can create a list   ArrayList lt String   gt  outerArr   new ArrayList lt String   gt        and add other lists to it like so   String   myString1    hey   hey   hey   hey      outerArr  add myString1   String   myString2    you   you   you   you    outerArr  add myString2     Now you can use the double loop below to show everything inside all lists  for int i 0 i lt outerArr size   i         String   myString  new String 4       myString outerArr get i      for int j 0 j lt myString length j           System out print myString j             System out print   n

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A 2d array is simply an array of arrays  The analog for lists is simply a List of Lists   ArrayList lt ArrayList lt String gt  gt  myList   new ArrayList lt ArrayList lt String gt  gt       I ll admit  it s not a pretty solution  especially if you go for a 3 or more dimensional structure

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I know that s an old question with good answers  but I believe I can add my 2 cents   The simplest and most flexible way which works for me is just using an almost  Plain and Old Java Object  class2D to create each  row  of your array   The below example has some explanations and is executable  you can copy and paste it  but remember to check the package name    package my2darraylist   import java util ArrayList  import java util List  import javax swing JPanel   public class My2DArrayList       public static void main String   args                   This is your  2D  ArrayList                     List lt Box gt  boxes   new ArrayList lt  gt                 Add your stuff                    Box stuff   new Box            stuff setAString   This is my stuff            stuff addString  My Stuff 01            stuff addInteger  1            boxes add  stuff                Add other stuff                    Box otherStuff   new Box            otherStuff setAString   This is my other stuff            otherStuff addString  My Other Stuff 01            otherStuff addInteger  1            otherStuff addString  My Other Stuff 02            otherStuff addInteger  2            boxes add  otherStuff                List the whole thing         for   Box box   boxes                        System out println  box getAString                  System out println  box getMyStrings   size                  System out println  box getMyIntegers   size                          class Box          Each attribute is a  Column  in you array                private String aString      private List lt String gt  myStrings   new ArrayList lt  gt          private List lt Integer gt  myIntegers   new ArrayList lt  gt            Use your imagination               private JPanel jpanel       public void addString  String s                 myStrings add  s               public void addInteger  int i                 myIntegers add  i                  Getters  amp  Setters      public String getAString                 return aString             public void setAString String aString                this aString   aString             public List lt String gt  getMyStrings                 return myStrings             public void setMyStrings List lt String gt  myStrings                this myStrings   myStrings             public List lt Integer gt  getMyIntegers                 return myIntegers             public void setMyIntegers List lt Integer gt  myIntegers                this myIntegers   myIntegers             public JPanel getJpanel                 return jpanel             public void setJpanel JPanel jpanel                this jpanel   jpanel            UPDATE - To answer the question from  Mohammed Akhtar Zuberi  I ve created the simplified version of the program  to make it easier to show the results   import java util ArrayList   public class My2DArrayListSimplified        public static void main String   args                ArrayList lt Row gt  rows   new ArrayList lt  gt             Row row             Insert the columns for each row                        First Name  Last Name  Age         row   new Row  John         Doe       30           rows add row           row   new Row  Jane         Doe       29           rows add row           row   new Row  Mary         Doe        1           rows add row               Show the Array                    System out println  First t Last tAge            System out println  ----------------------            for  Row printRow   rows                        System out println                      printRow getFirstName       t                         printRow getLastName       t                        printRow getAge                          class Row           REMEMBER  each attribute is a column            private final String firstName      private final String lastName      private final int age       public Row String firstName  String lastName  int age                this firstName   firstName          this lastName   lastName          this age   age             public String getFirstName                 return firstName             public String getLastName                 return lastName             public int getAge                 return age             The code above produces the following result  I ran it on NetBeans    run  First    Last   Age ---------------------- John     Doe    30 Jane     Doe    29 Mary     Doe    1 BUILD SUCCESSFUL  total time  0 seconds

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You would use  List lt List lt String gt  gt  listOfLists   new ArrayList lt List lt String gt  gt       And then when you needed to add a new  row   you d add the list   listOfLists add new ArrayList lt String gt        I ve used this mostly when I wanted to hold references to several lists of Point in a GUI so I could draw multiple curves  It works well   For example   import java awt BasicStroke  import java awt Color  import java awt Dimension  import java awt Graphics  import java awt Graphics2D  import java awt Point  import java awt RenderingHints  import java awt Stroke  import java awt event MouseAdapter  import java awt event MouseEvent  import java util ArrayList  import java util List  import javax swing      SuppressWarnings  serial   public class DrawStuff extends JPanel      private static final int PREF W   400     private static final int PREF H   PREF W     private static final Color POINTS COLOR   Color red     private static final Color CURRENT POINTS COLOR   Color blue     private static final Stroke STROKE   new BasicStroke 4f      private List lt List lt Point gt  gt  pointsList   new ArrayList lt List lt Point gt  gt        private List lt Point gt  currentPointList   null      public DrawStuff           MyMouseAdapter myMouseAdapter   new MyMouseAdapter          addMouseListener myMouseAdapter         addMouseMotionListener myMouseAdapter             Override    public Dimension getPreferredSize           return new Dimension PREF W  PREF H             Override    protected void paintComponent Graphics g          super paintComponent g         Graphics2D g2    Graphics2D  g        g2 setRenderingHint RenderingHints KEY ANTIALIASING               RenderingHints VALUE ANTIALIAS ON         g2 setStroke STROKE         g setColor POINTS COLOR         for  List lt Point gt  pointList   pointsList             if  pointList size    gt  1                Point p1   pointList get 0               for  int i   1  i  lt  pointList size    i                     Point p2   pointList get i                  int x1   p1 x                 int y1   p1 y                 int x2   p2 x                 int y2   p2 y                 g drawLine x1  y1  x2  y2                  p1   p2                                         g setColor CURRENT POINTS COLOR         if  currentPointList    null  amp  amp  currentPointList size    gt  1             Point p1   currentPointList get 0            for  int i   1  i  lt  currentPointList size    i                  Point p2   currentPointList get i               int x1   p1 x              int y1   p1 y              int x2   p2 x              int y2   p2 y              g drawLine x1  y1  x2  y2               p1   p2                              private class MyMouseAdapter extends MouseAdapter          Override       public void mousePressed MouseEvent mEvt             currentPointList   new ArrayList lt Point gt              currentPointList add mEvt getPoint              repaint                    Override       public void mouseDragged MouseEvent mEvt             currentPointList add mEvt getPoint              repaint                    Override       public void mouseReleased MouseEvent mEvt             currentPointList add mEvt getPoint              pointsList add currentPointList            currentPointList   null           repaint                     private static void createAndShowGui           JFrame frame   new JFrame  DrawStuff          frame setDefaultCloseOperation JFrame EXIT ON CLOSE         frame getContentPane   add new DrawStuff           frame pack          frame setLocationRelativeTo null         frame setVisible true            public static void main String   args          SwingUtilities invokeLater new Runnable              public void run                 createAndShowGui

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Declaring a two dimensional ArrayList    ArrayList lt ArrayList lt String gt  gt  rows   new ArrayList lt String gt       Or    ArrayList lt ArrayList lt String gt  gt  rows   new ArrayList lt  gt       Or  ArrayList lt ArrayList lt String gt  gt  rows   new ArrayList lt ArrayList lt String gt  gt        All the above are valid declarations for a two dimensional ArrayList   Now  Declaring a one dimensional ArrayList   ArrayList lt String gt  row   new ArrayList lt  gt       Inserting values in the two dimensional ArrayList    for int i 0  i lt 5  i         ArrayList lt String gt  row   new ArrayList lt  gt         for int j 0  j lt 5  j             row add  Add values here               rows add row        fetching the values from the two dimensional ArrayList    for int i 0  i lt 5  i         for int j 0  j lt 5  j             System out print rows get i  get j                    System out println

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If your platform matrix supports Java 7 then you can use like below  List lt List lt String gt  gt  myList   new ArrayList lt  gt

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for  Project project   listOfLists        String nama project   project getNama project        if  project getModelproject   size    gt  1            for  int i   1  i  lt  project getModelproject   size    i                  DataModel model   project getModelproject   get i               int id laporan   model getId                String detail pekerjaan   model getAlamat

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Infact  2 dimensional array is the list of list of X  where X is one of your data structures from typical ones to user-defined ones  As the following snapshot code  I added row by row into an array triangle  To create each row  I used the method add to add elements manually or the method asList to create a list from a band of data   package algorithms   import java util ArrayList  import java util Arrays  import java util List   public class RunDemo            param args     public static void main String   args           Get n     List lt List lt Integer gt  gt  triangle   new ArrayList lt List lt Integer gt  gt          List lt Integer gt  row1   new ArrayList lt Integer gt  1       row1 add 2       triangle add row1        List lt Integer gt  row2   new ArrayList lt Integer gt  2       row2 add 3  row2 add 4       triangle add row2        triangle add Arrays asList 6 5 7        triangle add Arrays asList 4 1 8 3         System out println  Size      triangle size         for  int i 0  i lt triangle size   i            System out println triangle get i           Running the sample  it generates the output   Size   4  2   3  4   6  5  7   4  1  8  3

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Here s how to make and print a 2D Multi-Dimensional Array using the ArrayList Object    import java util ArrayList   public class TwoD ArrayListExample       static public ArrayList lt ArrayList lt String gt  gt  gameBoard   new ArrayList lt ArrayList lt String gt  gt          public static void main String   args            insertObjects            printTable gameBoard              public static void insertObjects             for  int rowNum   0  rowNum    8  rowNum                  ArrayList lt String gt  oneRow   new ArrayList lt String gt                 gameBoard add rowNum  oneRow                for  int columnNum   0  columnNum    8  columnNum                      String description   Description of Objects  row     rowNum      column     columnNum                      oneRow add columnNum  description                                         The printTable method prints the table to the console     private static void printTable ArrayList lt ArrayList lt String gt  gt  table            for  int row   0  row    8  row                  for  int col   0  col    8  col                      System out println  Printing                row     row     column     col                   System out println table get row  get col  toString                                     System out println   n

[java] Two dimensional array list

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