How can i trace this code by hand?

public static $>$ void heapSort$($T$[]$ ar$)$

$\{$

ArrayList list $=$ new ArrayList$()$;

for $($int i $=0$; i $$ ar$.$length; $++$i$)$

add$($list$,$ ar$[$i$])$;

$\}$

public static $>$ void add$($ArrayList list, T t$)$

$\{$

list.add$($t$)$;

if $($list$.$size$()==1)$

return;

int curentIndex $=$ list.size$()-1$;

while $($curentIndex $>0$

&& list.get$($curentIndex$).$compareTo$($list$.$get$(($curentIndex $-1)/2))>0)$

$\{$

T temp $=$ list.get$(($curentIndex $-1)/2)$;

list.set$(($curentIndex $-1)/2,$ list.get$($curentIndex$))$;

list.set$($curentIndex$,$ temp$)$;

curentIndex $=($curentIndex $-1)/2$;

if $($ curentIndex $==3)$

$\{$

System.out.println$($list$.$get$($curentIndex$))$;

return;

$\}$

$\}$

$\}$

public static void main$($String$...$ ar$)$

$\{$

Integer$[]$ ar$3=\{10,2,20,1,12,8,3,56,1\}$;

heapSort$($ar$3)$;

$\}$