Stream API in Java 8: How to paginate a collection using limit() and skip() methods

Stream API in Java 8: How to use the limit() and skip() methods to paginate collections

Introduction:
During the development process, we often need to display data in paging. The Stream API introduced in Java 8 provides us with a convenient and efficient way to handle paging. This article will introduce how to use the limit() and skip() methods in the Stream API to paginate collections, with code examples.

1. The limit() method
The limit() method is an intermediate operation method in the Stream API. It is used to limit the number of elements obtained from the stream. It accepts a parameter n, which means to obtain at most n elements from the stream.

The following is a sample code that uses the limit() method for paging processing:

List<String> list = Arrays.asList("Apple", "Banana", "Orange", "Grape", "Kiwi");
int pageSize = 2;
int pageNumber = 1;

List<String> result = list.stream()
                         .skip(pageSize * pageNumber)
                         .limit(pageSize)
                         .collect(Collectors.toList());

System.out.println(result);

In the above code, we have a string list containing 5 elements. We require 2 elements to be displayed on each page to display the content of the first page. First we use the skip() method to skip the first two elements (pageSize * pageNumber), then use the limit() method to limit the acquisition of two elements, and finally use the collect() method to collect the results into a new list.

Run the above code, the output result is:

[Orange, Grape]

Through the limit() method, we successfully obtained the two elements of the first page from the original list.

2. Skip() method
The skip() method is an intermediate operation method in the Stream API. It is used to skip the first n elements in the stream. It accepts a parameter n, which represents the number of elements to skip.

The following is a sample code that uses the skip() method for paging processing:

List<String> list = Arrays.asList("Apple", "Banana", "Orange", "Grape", "Kiwi");
int pageSize = 2;
int pageNumber = 2;

List<String> result = list.stream()
                         .skip(pageSize * pageNumber)
                         .limit(pageSize)
                         .collect(Collectors.toList());

System.out.println(result);

In the above code, we still have a string list containing 5 elements. We require 2 elements to be displayed on each page to display the content of the second page. First we use the skip() method to skip the first four elements (pageSize * pageNumber), then use the limit() method to limit the acquisition of two elements, and finally use the collect() method to collect the results into a new list.

Run the above code, the output result is:

[Kiwi]

Through the skip() method, we successfully obtained an element of the second page from the original list.

Summary:
By using the limit() and skip() methods in the Stream API, we can easily paginate the collection. The limit() method is used to limit the number of elements obtained, while the skip() method is used to skip a specified number of elements. The combination of these two methods can achieve the needs of paging function.

Of course, in addition to the limit() and skip() methods, the Stream API also provides many other operation methods, such as filter(), map(), etc., which can be flexibly processed according to needs. I hope the content of this article will be helpful to your understanding and use of the Stream API.

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