下面代码的运行输出结果是（ ）。public class example{public static void main(String args[]) { int X=0; if(X>0) X=1; switch(X) { case 1: System.out.println(1); case 0: System.out.println(0); case 2: System.out.println(2);break; case 3: System.out.println(3); default:System.out.println(4); break; } }}