java基础知识点---size(),length(),length的区别

List<Integer> a=new ArrayList<Integer>();

a.add(1);

System.out.println(a.size());

int b[]={1,2,3};

System.out.println(b.length);

String s=new String("Hello");

System.out.println(s.length());

out:  1 3 5

泛型 size()

数组 length

字符串 length()