Why is it that the toUpperCase of String is not a static method, but can be called by String::toUpperCase?
List<String> myList =
Arrays.asList("a1", "a2", "b1", "c2", "c1");
myList
.stream()
.filter(s -> s.startsWith("c"))
.map(String::toUpperCase)
.sorted()
.forEach(System.out::println);
tutorials on the Internet
refer to java documentation: Method References
roughly means that java calls the method with the first parameter passed to it as an instance.
how do I convert object properties of type String to int sorting? attribute area_size is a String type attribute, but the values are all numeric types. I want to sort it first by Id, and then by the size of area_size. Here s my code: defectFS.strea...
Map < String,List < String > replace with Map < String,Java > the original data structure is as follows: Map < String,String > map=new LinkedMultiValueMap < > (); map.add ( "java ", "1.7 "); map.add ( "java ", "1.8 "); the map after adding data ...
topic description lambda groupingBy Advanced questions List < A > how to convert to List < B > sources of topics and their own ideas looked up a lot of materials and found that most of the Internet teaches how to convert List into Map < String,Li...