java - Default size of ArrayList -

looking through piece of code noticed 1 strange initialization of arraylist:

... = new arraylist<..>(0); 

i've opened javase 7 sources , saw inner elementdata arrray initialized empty array constant - {}. when pass capacity arraylist constructor same - new object[0]. question is: there difference between new arraylist(0) , new arraylist() ? shouldn't arraylist set default capacity size smth 10 ?

thanks answers.

an arraylist has internal array store list elements.

there difference between 2 constructor calls in java 7 , 8:

if new arraylist<>(0) arraylist creates new object array of size 0.

if new arraylist<>() arraylist uses static empty object array of size 0 , switches own private array once add items list.

edit:

the javadoc of default arraylist constructor seems contradict this.

/**  * constructs empty list initial capacity of ten.  */ public arraylist() {     super();     this.elementdata = empty_defaultcapacity_empty_elementdata; // = static, empty } 

but not create element array of length 10 immediately, instead when add elements or ensure capacity:

public void ensurecapacity(int mincapacity) {     int minexpand = (elementdata != defaultcapacity_empty_elementdata)         // size if not default element table         ? 0         // larger default default empty table. it's         // supposed @ default size.         : default_capacity; // = 10      if (mincapacity > minexpand) {         ensureexplicitcapacity(mincapacity);     } }