The way and method of achieving a smooth collection in the Java library
The way and method of achieving a smooth collection in the Java library
introduce:
Smooth collection refers to a programming style that operates the collection through the chain method call, which can make the code easier to read, concise, and provide richer operating functions.This article will introduce how to achieve a smooth collection path and method in the Java library, and provide relevant Java code examples.
1. Use the Stream API of Java 8
Java 8 introduced Stream API, which provides a wealth of collection operation functions that can operate the collection through a chain method call.The following is an example that demonstrates how to use the Stream API to filter, map and collect collection elements:
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> result = numbers.stream()
.filter(n -> n > 2)
.map(n -> n * 2)
.collect(Collectors.toList());
System.out.println (result); // Output: [6, 8, 10]
In the above example, we first convert the collection into stream through the `stream ()` method, and then filter out elements greater than 2 through the `Filter ()` method, and then use the `map ()` method to multiply each element with2. Finally, the results are collected into a new set through the `collect ()` method.
2. Use the smooth set library
In addition to using the Stream API of the Java 8, you can also use some smooth collection libraries to achieve a programmatic programming style.These libraries provide richer collective operation functions and can provide more powerful functions.The following is an example that demonstrates how to use the Google Guava library to achieve a smooth collection:
List<Integer> numbers = Lists.newArrayList(1, 2, 3, 4, 5);
List<Integer> result = FluentIterable.from(numbers)
.filter(n -> n > 2)
.transform(n -> n * 2)
.toList();
System.out.println (result); // Output: [6, 8, 10]
In the above example, we first use the method to convert the collection into a smooth collection, and then filter out elements greater than 2 through the `Filter ()` method, and then use the `Transform () method to make each every wayThe element is multiplied by 2, and finally converts the results into a new set through the `Tolist ()" method.
3. Customized smooth collection
In addition to using the existing smooth collection library, you can also customize the smooth collection class.The following is an example that demonstrates how to achieve a simple smooth collection class:
public class FluentCollection<E> {
private final List<E> elements;
private FluentCollection(List<E> elements) {
this.elements = elements;
}
public static <E> FluentCollection<E> from(List<E> elements) {
return new FluentCollection<>(elements);
}
public FluentCollection<E> filter(Predicate<? super E> predicate) {
List<E> filtered = elements.stream()
.filter(predicate)
.collect(Collectors.toList());
return new FluentCollection<>(filtered);
}
public <R> FluentCollection<R> transform(Function<? super E, ? extends R> function) {
List<R> transformed = elements.stream()
.map(function)
.collect(Collectors.toList());
return new FluentCollection<>(transformed);
}
public List<E> toList() {
return elements;
}
}
In the example above, we define a `FluentCollection` class, which contains the method of` `From ()`, `Filter (),` `)` and `tolist ().Smooth collection, filtering elements, conversion elements, and converting results into a new collection.
When using a customized smooth collection class, you can call the chain method in the following way:
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
List<Integer> result = FluentCollection.from(numbers)
.filter(n -> n > 2)
.transform(n -> n * 2)
.toList();
System.out.println (result); // Output: [6, 8, 10]
Summarize:
This article introduces the ways and methods of achieving a smooth collection in the Java library.By using the STREAM API, smooth collection library or customized collection class of Java 8, you can operate a collection in a more easy -to -read and concise way, and provide richer operating functions.
