Collections,Arrays

1.Collections,http://www.cnblogs.com/Eason-S/p/5786066.html

2.Arrays,https://blog.csdn.net/liu_yanzhao/article/details/70847050

3.List和Array互转

(1)List转Array,JVM会记录你本来的类型，不允许向本来类型往下转型

List<Integer> li=new ArrayList<>(){{add(5);add(6);add(9);add(8);}};
Integer[] a=new Integer[li.size()];
li.toArray(a);              //方法1转成具体类型
Object[] b=li.toArray();    //方法2转成只能Object,因为JVM不允许向下转型

(2)Array转List

Integer[] a={1,2,3,4,5};
List<Integer> li =new ArrayList<>(Arrays.asList(a));

https://blog.csdn.net/zjx2016/article/details/78273192