What are the methods for sorting collections in java

1. The Collections tool class provides a static method sort method. The input parameter is a List collection. Compared with Comparator, the given List collection is sorted. The above example code creates an anonymous inner class to participate in. This kind of similar operation can be seen everywhere in our daily work.

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. Use Lambda expressions

For code blocks that only contain one line of methods, we can omit the curly brackets and directly return the key code, which can be simpler.

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

What collection classes are there in Java?

Collections in Java are mainly divided into four categories:

1. List: ordered, repeatable;

2. Queue: ordered and repeatable;

3. Set: non-repeatable;

4. Map: unordered, with unique keys and non-unique values.

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