I need to identify the errors and explain and correct code

$1.$ public class Oops $\{$

$2.$ public static void main$($String$[]$ args$)\{$

$3.$ int x;

$4.$ System.out.println$("$x is$"$ x$)$;

$5.$ int x $=15\mathrm{.}2$;

$6.$ System.out.println$("$x is now $+$ x$")$;

$7.$ int y;

$8.$ y $=$ int x $+1$;

$9.$ int z;

$10.$ sum$($x$,$ y$)$;

$11.$ system.out.println$("$z are $"$ z$)$;

$12.\}$

$13.$ public static void sum$($double x$,$ double y$)\{$

$14.$ int sum $=$ x $+$ y;

$15.$ return sum;

$16.\}$

$17.\}$