System.arraycopy() in Java

java.lang.System class provides useful methods for standard input and output, for loading files and libraries or to access externally defined properties. The java.lang.System.arraycopy() method copies a source array from a specific beginning position to the destination array from the mentioned position. No. of arguments to be copied are decided by len argument.
The components at source_Position to source_Position + length – 1 are copied to destination array from destination_Position to destination_Position + length – 1

Class Declaration

public final class System
   extends Object

arraycopy
Syntax :



public static void arraycopy(Object source_arr, int sourcePos,
                            Object dest_arr, int destPos, int len)
Parameters : 
source_arr : array to be copied from
sourcePos : starting position in source array from where to copy
dest_arr : array to be copied in
destPos : starting position in destination array, where to copy in
len : total no. of components to be copied.

Implementation

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// Java program explaining System class method - arraycopy()
import java.lang.*;
public class NewClass
{
    public static void main(String[] args)
    {
        int s[] = { 10, 20, 30, 40, 50, 60, 70, 80, 90, 100};
        int d[] = { 15, 25, 35, 45, 55, 65, 75, 85, 95, 105};
  
        int source_arr[], sourcePos, dest_arr[], destPos, len;
        source_arr = s;
        sourcePos = 3;
        dest_arr = d;
        destPos = 5;
        len = 4;
  
        // Print elements of source
        System.out.print("source_array : ");
        for (int i = 0; i < s.length; i++)
            System.out.print(s[i] + " ");
        System.out.println("");
  
        System.out.println("sourcePos : " + sourcePos);
         
        // Print elements of source
        System.out.print("dest_array : ");
        for (int i = 0; i < d.length; i++)
            System.out.print(d[i] + " ");
        System.out.println("");
         
        System.out.println("destPos : " + destPos);
         
        System.out.println("len : " + len);
         
        // Use of arraycopy() method
        System.arraycopy(source_arr, sourcePos, dest_arr, 
                                            destPos, len);
         
        // Print elements of destination after
        System.out.print("final dest_array : ");
        for (int i = 0; i < d.length; i++)
            System.out.print(d[i] + " ");
    }

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Output:

source_array : 10 20 30 40 50 60 70 80 90 100 
sourcePos : 3
dest_array : 15 25 35 45 55 65 75 85 95 105 
destPos : 5
len : 4
final dest_array : 15 25 35 45 55 40 50 60 70 105 

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