Java array concatenation string several performance comparison (reprint)

The array int[] arr = {0,1,2,3,4,5,6,7,8,9} is stitched into [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] Strings:

StringBuilder sb = new StringBuilder (arr.length*3); StringBuilder (arr.length*3) performance ratio StringBuilder () high
Sb.append ("[");

Notation 1
for (int i = 0, len = arr.length; i < Len; i++)
{
if (i > 0) {
Sb.append (",");
}

Sb.append (Arr[i]);
}
Return Sb.append ("]"). ToString ();


Two
int iMax = arr.length-1;
for (int i = 0;; i++) {
Sb.append (Arr[i]);
if (i = = IMax) {
Return Sb.append ("]"). ToString ();
}
Sb.append (",");
}


Three of the wording
int offset = arr.length-1;
for (int i = 0; i < offset; i++)
{
Sb.append (Arr[i]). Append (",");
}
Sb.append (Arr[offset]). Append ("]");

return sb.tostring ();

Performance efficiency:notation 3 > Writing 2 > Notation 1

The 3 efficiency is high because the if condition judgment is removed in the for loop.

Java array concatenation string several performance comparison (reprint)