Метод chars stream java

What is the String.chars method in Java?

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Overview

The chars() method is an instance method of the String class. It returns an IntStream that consists of the code point values of the characters in the given string. This method was added to the String class in Java 9.

Syntax

Parameters

This method has no parameters.

Return value

This method returns an IntStream of char values from the string.

Code

import java.util.stream.IntStream;
 
class Main  
public static void main(String[] args)  
// Define a string
 
String string = "hello-educative";
 
// use the chars method to get a stream of char values
 
IntStream codePointStream = string.chars();
 
// convert the code points back to characters and print the output
 
codePointStream.mapToObj(Character::toChars).forEach(System.out::println);
 
>
>

Explanation

• Line 1: We import the relevant packages.
• Line 6: We define a string called string .
• Line 9: We use the chars() method to get a stream of character values.
• Line 12: We convert the code points back to characters and print the output.

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Источник

Преобразование строки в список символов в Java

В этом посте мы обсудим, как преобразовать строку в список символов в Java.

1. Наивное решение

Наивным решением является создание нового списка и добавление в него элементов с помощью цикла for-each, как показано ниже:

результат:

Мы также можем использовать простой цикл for, как показано ниже:

результат:

2. Использование Java 9

Мы можем назвать chars() метод строки в Java 9 и выше, который возвращает IntStream . Затем мы конвертируем IntStream к Stream из Character с помощью лямбда-выражения и соберите Stream в новый список с помощью Collector .

результат:

Мы также можем использовать IntStream.range() для прямого доступа к каждому символу и добавления его в список, как показано ниже:

результат:

3. Использование AbstractList Interface

Чтобы создать неизменяемый список, поддерживаемый строкой, мы можем реализовать AbstractList интерфейс.

результат:

4. Использование библиотеки Guava

Другой вероятный способ преобразования строки в список символов — использование какой-либо сторонней библиотеки. Guava Chars Класс предоставляет несколько статических служебных методов, относящихся к примитивам char. Одним из таких методов является asList() , который возвращает список фиксированного размера, поддерживаемый массивом примитивов char.

Источник

Converting String to Stream of chars

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1. Overview

Java 8 introduced the Stream API, with functional-like operations for processing sequences. If you want to read more about it, have a look at this article.

In this quick article, we’ll see how to convert a String to a Stream of single characters.

2. Conversion Using chars()

The String API has a new method – chars() – with which we can obtain an instance of Stream from a String object. This simple API returns an instance of IntStream from the input String.

Simply put, IntStream contains an integer representation of the characters from the String object:

String testString = "String"; IntStream intStream = testString.chars();

It’s possible to work with the integer representation of the characters without converting them to their Character equivalent. This can lead to some minor performance gains, as there will be no need to box each integer into a Character object.

However, if we’re to display the characters for reading, we need to convert the integers to the human-friendly Character form:

Stream characterStream = testString.chars() .mapToObj(c -> (char) c);

3. Conversion Using codePoints()

Alternatively, we can use the codePoints() method to get an instance of IntStream from a String. The advantage of using this API is that Unicode supplementary characters can be handled effectively.

Supplementary characters are represented by Unicode surrogate pairs and will be merged into a single codepoint. This way we can correctly process (and display) any Unicode symbol:

IntStream intStream1 = testString.codePoints();

We need to map the returned IntStream to Stream to display it to users:

Stream characterStream2 = testString.codePoints().mapToObj(c -> (char) c); 

Stream stringStream = testString.codePoints() .mapToObj(c -> String.valueOf((char) c));

jshell> String str = "Hello World"; str ==> "Hello World" jshell> str.chars().forEach(System.out::println); 72 101 108 108 111 32 87 111 114 108 100 jshell>

jshell> str.chars().parallel().forEach(c -> System.out.println(Character.valueOf((char) c))); W o r l d l o H e l jshell>

jshell> String str = "Hello World"; str ==> "Hello World" jshell> List charStr = new ArrayList<>(); charStr ==> [] jshell> str.chars().map(x -> x + 1).forEach(y -> charStr.add(Character.valueOf((char) y))); jshell> System.out.println(charStr); [I, f, m, m, p, !, X, p, s, m, e] jshell>