Variable length Dynamic Arrays in Java

Question

I was wondering how to initialise an integer array such that it s size and values change through out the execution of my program  any suggestions

User · Answer

I answered this question and no you do not need an arraylist or any other thing this was an assignment and I completed it so yes arrays can increase in size  Here is the link  How to use Java Dynamic Array and here is the link for my question which i answered  Java Dynamic arrays

User · Answer

Simple code for dynamic array  In below code then array will become full of size we copy all element to new double size array variable size array  sample code is below   public class DynamicArray    static   int   increaseSizeOfArray int   arr             int   brr new int  arr length 2              for  int i   0  i  lt  arr length  i               brr i  arr i                              return brr         public static void main String   args         int   arr new int 5         for  int i   0  i  lt  11  i                if  i lt arr length                  arr i  i 100                        else                 arr increaseSizeOfArray arr                 arr i  i 100                              for  int i   0  i  lt  arr length  i           System out println  arr   arr i                 Source   How to make dynamic array

User · Answer

It is recommend to use List to deal with small scale size  If you have a huge number of numbers  NEVER use List and autoboxing   List lt  Integer  list    For every single int  a new Integer is auto created  You will find it getting slow when the size of the list increase  These Integers are unnecessary objects  In this case  to use a estimated size would be better   int   array   new int ESTIMATED SIZE

User · Answer

Arrays in Java are of fixed size  What you d need is an ArrayList  one of a number of extremely valuable Collections available in Java   Instead of   Integer   ints   new Integer x    you use   List lt Integer gt  ints   new ArrayList lt Integer gt       Then to change the list you use ints add y  and ints remove z  amongst many other handy methods you can find in the appropriate Javadocs   I strongly recommend studying the Collections classes available in Java as they are very powerful and give you a lot of builtin functionality that Java-newbies tend to try to rewrite themselves unnecessarily

User · Answer

How about using a List instead  For example  ArrayList lt integer gt

User · Answer

I disagree with the previous answers suggesting ArrayList  because ArrayList is not a Dynamic Array but a List backed by an array  The difference is that you cannot do the following   ArrayList list   new ArrayList 4   list put 3  Test      It will give you an IndexOutOfBoundsException because there is no element at this position yet even though the backing array would permit such an addition  So you need to use a custom extendable Array implementation like suggested by  randy-lance

User · Answer

Arrays are fixed size once instantiated  You can use a List instead   Autoboxing make a List usable similar to an array  you can put simply int-values into it   List lt Integer gt  list   new ArrayList lt Integer gt     list add 1   list add 2   list add 3

User · Answer

You can t change the size of an array  You can  however  create a new array with the right size and copy the data from the old array to the new   But your best option is to use IntList from jacarta commons   here   It works just like a List but takes less space and is more efficient than that  because it stores int s instead of storing wrapper objects over int s  that s what the Integer class is

User · Answer

Yes  use ArrayList   In Java   normal  arrays are fixed-size   You have to give them a size and can t expand them or contract them  To change the size  you have to make a new array and copy the data you want - which is inefficient and a pain for you   Fortunately  there are all kinds of built-in classes that implement common data structures  and other useful tools too   You ll want to check the Java 6 API for a full list of them   One caveat  ArrayList can only hold objects  e g  Integers   not primitives  e g  ints    In MOST cases  autoboxing autounboxing will take care of this for you silently  but you could get some weird behavior depending on what you re doing

[java] Variable length (Dynamic) Arrays in Java

Examples related to java

Examples related to arrays

Examples related to dynamic

Examples related to arraylist