= list.stream().map(x -> Long.parseLong(x)).collect(Collectors.toList());
//结果:[1, 2, 3, 4,...(collect2);
String collect3 = list.stream().collect(Collectors.joining(","));
//结果:a...,b,ab,a,b,ab
System.out.println(collect3);
Map> collect4 = list.stream...}
System.out.println(collect4);
Long collect = list.stream().collect(Collectors.counting...());
//结果:6
System.out.println(collect);
String collect5 = list.stream().collect