什么是正确的 lambda 这个内部 class

Question

I have following code:

  private List<String> searchFolder(File tempDirFile) {
            List<String> listFile;
            listFile = Arrays.asList(tempDirFile.list(new FilenameFilter() {
                @Override
                public boolean accept(File dir, String name) {
                    return name.contains(type);
                }
            }));
            return listFile;
        }

SonarLint tells me to "Make this anonymous inner class a lambda". So this

new FilenameFilter(){.....}

is supposed to be "converted" into a lambda. I looked up cases and scenarios, but wasn't able to find a solution for this specific case I have here.

Answer 1

As requestedd by OP: FilenameFilter is a FunctionalInterface it has only one abstract method and it can be implemented with a lambda that match its signature and java compiler will infer the type:

Arrays.asList(tempDirFile.list((dir, name) -> name.contains(type)));

Edit: the @FunctionalInterface annotation is optional you can create lambda for any interface with only one abstract method even if not annotated with it.

Edit 2: More about lambda expression https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html