Как из строки сделать массив java

Преобразование строки в массив символов в Java

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

1. Наивное решение

Наивное решение состоит в том, чтобы использовать обычный цикл for, чтобы прочитать все символы в строке и присвоить их массиву символов один за другим. Этот подход очень эффективен для небольших строк.

результат:

[J, a, v, a]

2. Использование String.toCharArray() метод

Мы можем преобразовать строку в массив символов, используя String.toCharArray() метод, как показано ниже:

результат:

[J, a, v, a]

3. Использование отражения

Для длинных строк ничто не сравнится с отражением с точки зрения производительности. Мы можем проверить любую строку, используя отражение, и получить доступ к резервному массиву указанной строки.

результат:

[J, a, v, a]

Это все о преобразовании строки в массив символов в Java.

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How to Convert String to Array in Java

Sometimes, we need to convert a string to array in Java based on some criteria to address one problem or another.

Unfortunately, Java does not provide any direct way to accomplish this automatically!

So, in this tutorial, we’ll try to cover in-depth the most commonly used methods to turn a string object into an array.

Feel free to check our article on how to convert an array to a string if you are curious about how to do the opposite.

Split String into an Array in Java

There are many options out there that you can use to tackle Java string-to-array conversion. We’ll walk you through from beginning to end so you can implement each method without getting confused.

Using split() Method

The split() method belongs to the String class and it’s mainly used to split a simple string into tokens.

This method returns a String[] array by splitting the specified string using a delimiter of your choice. The separator can be a string or a regular expression.

Let’s discover together how we can use the split() method to convert a string to an array:

Using Pattern.split()

The main purpose of this split() method is to break the passed string into an array according to a given pattern defined using the compile method.

The following example will show you how to use the split() and the compile() methods to convert a String object to a String[] array using a regular expression:

Using StringUtils.split() Method

StringUtils is an utility class provided by the Apache Commons project. This class offers multiple null-safe methods related to String manipulation.

It’s a good alternative since the java.lang.String package can’t handle all the String related operations.

In order to use StringUtils class, you need to import the commons-lang3 JAR file into your project. You can download it and import it manually or you can just use a dependency management tool like Maven or Gradle.

You can download the latest version of Apache Commons Lang 3 from here

The following is an example of how to use StringUtils to convert a particular string to an array in Java:

Using StringTokenizer Class

StringTokenizer is a legacy class that belongs to java.util package. It helps split a string object into small parts called tokens.

The process of breaking a string into multiple tokens is called String tokenization. Space is the default delimiter used for String tokenization!

Let’s see a simple example of how to use the StringTokenizer class to tokenize a string object in Java.

Using Guava Library

Guava is a Java-based library developed by Google. It provides some great mechanisms and utilities for joining and splitting strings.

To use Guava library, you need to add it to your Java project first. If you are using Maven, you can include the Guava dependency into your POM file.

If you’re not a big fan of dependencies management tools, then you have to follow these steps:

Download the Google Guava JAR file.

Import the JAR file into your project.

Add the JAR file as a library.

The Guava’s Splitter class provides an interesting method called splitToList(). The Splitter uses a delimiter to split the given String into a collection of elements.

The separator can be specified as a single character, a fixed string, or a regex pattern!

Unlike other classes, Splitter provides a more object-orientated way to parse the string and split it.

The following example shows how to split a string object into a List:

How to Convert String to char Array Java?

Java provides several ways to convert a string into an array of characters. So, let’s get an up-close look at some of the available methods.

Using toCharArray() Method

This method of the String class returns an array of characters from a given string. The returned array has the same length as the length of the string.

The following example demonstrated how to convert a string object to char array using the toCharArray() method.

Using getChars()

public void getChars(int start, int end, char[] arr, int arrstart) is used to copy characters from a given string into a char[] array.

start: Index of the first character of the string to copy.

end: Index after the last character to copy.

arr: Destination array where chars will be copied.

arrstart: The first index in array where the first character will be pushed.

Java 8 chars() Method

chars() is a new method introduced in Java 8. It can be used to create an instance of Stream from a String object.

You can use the mapToObj() and the toArray() methods with chars() method to convert a string to array of characters.

Conclusion

In this article, you learned how to convert string to array in Java. You learned also different ways of splitting a simple string into a char array.

Convert String to Array in Java

Strings in Java are objects which represent a sequence of characters. Java Strings are immutable which implies their value cannot be changed once created.

To convert a String to a char array, we can use a simple for loop or toCharArray() method.

String array in Java is an array of Strings. Arrays in Java are of fixed length. We can convert a String to an array using any one of the following ways: String.split() , Pattern.split() , String[] <> , and toArray() .

Scope

This article aims to:

• Explain the different ways to convert a String to a character array in Java
• Discuss four different ways to convert a String to a String array
  • Using String.split() method
  • Using Pattern.split() method
  • Using toArray() method
  • Using String[] approach

  Introduction

  Strings in Java are objects of String class which are nothing but a sequence of characters. Strings are immutable in Java which implies when we modify the value of a String, a new String object is created instead of modifying the value of the existing String object. We can import String class in Java from the java.lang package.

  Java array is an object which contains elements of a similar data type. Additionally, The elements of an array are stored in a contiguous memory locations. The size of arrays cannot be changed in Java which implies an array is a set of fixed number of elements.

  In this article, we will go through character and string arrays in Java.

  Convert a String to Character Array in Java

  There are two different ways to covert a String object to a character array in Java:

  1. Naive Approach

  A simple method is to read all of the characters in the string and assign them one by one to a Character array using a standard for-loop.

  Detailed Procedure:

  1. Get the string.
  2. Create a character array that is the same length as the string.
  3. Copy the character at the i t h i^ i t h position of the string to the i t h i^
     i t h index of the array by traversing the string.
  4. Return or perform the operation on the character array.

  Code:

  Output:

  2. Using toCharArray() Method

  To convert a string to a char array, we can use the toCharArray() function.

  Detailed Procedure:

  1. Get the string.
  2. Call the toCharArray() method and store the character array returned by it in a character array.
  3. Return or perform operation on the character array.

  Code:

  Output:

  Converting String to String Array in Java

  We'll learn how to convert a string to an array of strings in Java in this section.

  In Java, there are four ways to convert a String to a String array:

  • Using String.split() Method
  • Using Pattern.split() Method
  • Using String[ ] Approach
  • Using toArray() Method

  Using String.split() Method

  The String.split() method is used to split a string into distinct strings based on the delimiter provided (whitespace or other symbols). These entities can be directly stored in a string array.

  Consider the following example, which shows how to convert a string to array in Java using the String.split() method.

  Output:

  Example 2: We changed the string to array in Java in the following example using the # delimiter.

  Output:

  Using Pattern.split() Method

  The Pattern.split() method uses a regular expression(pattern) as the delimiter to split a string into an array of strings.

  To use the technique, we have to import the Pattern class into our Java code as shown in the code below. This Pattern class can compile complex regex expressions.

  Consider the following example, in which we will split a string into an array by using whitespace as the delimiter.

  Output:

  Example 2: We may also use any string or pattern as a delimiter to break a string into an array. We've used the &d& delimiter here.

  Output:

  Using String[ ] Approach

  We can convert a string to string array by simply passing the string in the curly brackets of String [] <> . The impact of this conversion is that a String array will be created containing a single element — the input string itself.

  Consider the following example, which shows how to convert a string to an array in Java using the String[] <> approach.

  Output

  Using toArray() Method

  The toArray() function of the List class can also be used to convert a string to array in Java. It takes a list of type String as the input and converts each entity into an element of a string array.

  Consider the following example where we have converted the list of strings into a string array.

  toCharArray() в Java — Сделать из строки массив чаров

  

  Метод toCharArray() создает из строки массив чаров (от англ. — char).

  Синтаксис метода:

  Вызов:

  Пример:

  Если Вы запустите данный код на своем компьютере, в консоли Вы увидите следующее:

  

  Комментарии к коду:

  У нас есть строка «ABC». С помощью метода toCharArray() мы перевели эту строку в массив чаров <'A', 'B', 'C'>.

  Для того, чтобы продемонстрировать результат, мы создали цикл, и вывели на экран каждый элемент массива по отдельности.

  Данная статья написана Vertex Academy. Можно пройти наши курсы Java с нуля. Детальнее на сайте.