What are the two ways to create anonymous objects in java

1. Static tool method

Collections.sort accepts a list and a Comparator interface as input parameters. The Comparator implementation class can compare elements in the input list. Normally, you can create an anonymous Comparator object directly and pass it as a parameter to the sort method.

List<String> names = Arrays.asList("peter", "anna", "mike", "xenia");
 
Collections.sort(names, new Comparator<String>() {
    @Override
    public int compare(String a, String b) {
        return b.compareTo(a);
    }
});

2. Lambda expression

Collections.sort(names, (String a, String b) -> {
    return b.compareTo(a);
});

As you can see, this code is shorter and easier to read than the previous one. However, it can be even shorter:

Collections.sort(names, (String a, String b) -> b.compareTo(a));

Just one line of code, including the method body. You can even omit the braces {} and the return keyword. But this is not the shortest way of writing:

Collections.sort(names, (a, b) -> b.compareTo(a));

The Java compiler can automatically identify the type of parameters, so you can omit the type.

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