Java 一些容易出错小问题

xielioo

List<String>[] list = new ArrayList[3];//List<String>[] list = new ArrayList<String>[3];  语法错if(a == 1) {    //如果a为null会报异常 :shock: }map.put("NULL", null);String a = (String) map.get("NULL");System.out.println(a);   //打印null//Java Enum 枚举enum a {a,b,c};public static void main(String[] args) {a c = a.b;System.out.println(c + "\t" + c.ordinal());}/***result :b1*/public static Integer[] A = new Integer[] {B};public static Integer B = 1;public static void main(String[] args) {System.out.println(A[0]);}/*** result :0**/