copying array by value in java

Question

I tried to make an independent copy of an array but couldnt get one. see i cannot copy it integer by integer using a for loop because of efficiency reasons. Is there any other way? This was my code:

int[] temp = new int[arr.length]; 
temp = arr; 

Answer 1

Try using clone () method for this purpose. As I remember this is the only case where Josh Bloch in Effective Java recommended to use cloning.

int[] temp = arr.clone ();

But arrayCopy is much faster. Sample performance test on array of 3,000,000 elements:

System.arrayCopy time: 8ms
     arr.clone() time: 29ms
 Arrays.copyOf() time: 49ms
 simple for-loop time: 75ms