OPT.IRB

Use `System.arraycopy ()' instead of using a loop to copy an array

Description

This rule flags code where a loop is used to copy arrays.

`System.arraycopy ()' is much faster that using a loop to copy an array.

Example

 package OPT;
 
 public class IRB
 {
     void method () {
         int[] array1 = new int [100];
         for (int i = 0; i < array1.length; i++) {
             array1 [i] = i;
         }
         int[] array2 = new int [100];
         for (int i = 0; i < array2.length; i++) {
             array2 [i] = array1 [i];                 // Violation
         }
     }
 }

Repair

 package OPT;
 
 public class IRB
 {
     void method () {
         int[] array1 = new int [100];
         for (int i = 0; i < array1.length; i++) {
             array1 [i] = i;
         }
         int[] array2 = new int [100];
         System.arraycopy(array1, 0, array2, 0, 100);
     }
 }

Reference

http://www.cs.cmu.edu/~jch/java/speed.html