How to create a sub array from another array in Java

Question

How to create a sub-array from another array  Is there a method that takes the indexes from the first array such as   methodName object array  int start  int end    I don t want to go over making loops and making my program suffer   I keep getting error      cannot find symbol method copyOfRange int   int int    This is my code   import java util     public class testing        public static void main String    arg                    int   src   new int    1  2  3  4  5            int b1     Arrays copyOfRange src  0  2

User · Answer

Use copyOfRange method from java util Arrays class   int   newArray   Arrays copyOfRange oldArray  startIndex  endIndex    For more details   Link to similar question

User · Answer

Arrays copyOfRange     was added in Java 1 6  So perhaps you don t have the latest version  If it s not possible to upgrade  look at System arraycopy

User · Answer

JDK    1 8  I agree with all the answers above  There is also a nice way with Java 8 Streams   int   subArr   IntStream range startInclusive  endExclusive                           map i - gt  src i                            toArray      The benefit about this is  it can be useful for many different types of  src  array and helps to improve writing pipeline operations on the stream   Not particular about this question  but for example  if the source array was double   and we wanted to take average   of the sub-array   double avg   IntStream range startInclusive  endExclusive                       mapToDouble index - gt  src index                        average                        getAsDouble

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I you are using java prior to version 1 6 use System arraycopy   instead  Or upgrade your environment

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Using Apache ArrayUtils downloadable at this link you can easy use the method   subarray boolean   array  int startIndexInclusive  int endIndexExclusive      boolean  is only an example  there are methods for all primitives java types

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int newArrayLength   30    int   newArray   new int newArrayLength    System arrayCopy oldArray  0  newArray  0  newArray length

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You can use     JDK   1 5  Arrays copyOfRange Object   src  int from  int to    Javadoc    JDK  lt   1 5  System arraycopy Object   src  int srcStartIndex  Object   dest  int dstStartIndex  int lengthOfCopiedIndices      Javadoc

User · Answer

Yes  it s called System arraycopy Object  int  Object  int  int     It s still going to perform a loop somewhere though  unless this can get optimized into something like REP STOSW by the JIT  in which case the loop is inside the CPU    int   src   new int    1  2  3  4  5   int   dst   new int 3    System arraycopy src  1  dst  0  3      Copies 2  3  4 into dst

User · Answer

The code is correct so I m guessing that you are using an older JDK   The javadoc for that method says it has been there since 1 6   At the command line type   java -version   I m guessing that you are not running 1 6

[java] How to create a sub array from another array in Java?

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