Java string characters to array

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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String to Char Array Java Tutorial

Thanoshan MV

In this article, we’ll look at how to convert a string to an array of characters in Java. I’ll also briefly explain to you what strings, characters, and arrays are.

What is a Character in Java?

Characters are primitive datatypes. A character is a single character enclosed inside single quotation marks. It can be a letter, a digit, a punctuation mark, a space or something similar. For example:

What is a String in Java?

Strings are objects (reference type). A string is made up of a string of characters. It’s anything inside double quotation marks. For example:

What is an Array in Java?

Arrays are fundamental data structures which can store fixed number of elements of the same data type in Java. For example, let’s declare an array of characters:

Now, we have a basic understanding about what strings, characters, and arrays are.

Let’s Convert a String to a Character Array

1. Use toCharArray() Instance Method

toCharArray() is an instance method of the String class. It returns a new character array based on the current string object.

Let’s check out an example:

// define a string String vowels = "aeiou"; // create an array of characters char[] vowelArray = vowels.toCharArray(); // print vowelArray System.out.println(Arrays.toString(vowelArray));

When we convert a string to an array of characters, the length remains the same. Let’s check the length of both vowels and vowelArray :

System.out.println("Length of \'vowels\' is " + vowels.length()); System.out.println("Length of \'vowelArray\' is " + vowelArray.length);

Length of 'vowels' is 5 Length of 'vowelArray' is 5

We can use various ways to print an array. I used the toString() static method from the Arrays utility class.

You can read more about the toCharArray() instance method in the Java documentation.

2. Use charAt() Instance Method

charAt() is an instance method of the String class. It returns a character at the specified index of the current string.

NOTE: a string is zero index based, similar to an array.

Let’s see how we can convert a string to an array of characters using charAt() :

// define a string String vowels = "aeiou"; // create an array of characters. Length is vowels' length char[] vowelArray = new char[vowels.length()]; // loop to iterate each characters in the 'vowels' string for (int i = 0; i < vowels.length(); i++) < // add each character to the character array vowelArray[i] = vowels.charAt(i); >// print the array System.out.println(Arrays.toString(vowelArray));

You can read more about the charAt() instance method in the Java documentation.

I just showed you another way of converting a string to a character array, but we can use the toCharArray() method to easily convert instead of creating loops and iterating them.

Please feel free to let me know if you have any suggestions or questions.

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Happy Coding ❤️

More on Programming in Java

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Java char to String, String to char array

While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

Today we will look into java char to String program. We will also learn how to convert String to a char array.

Java char to String

1. char is a primitive data type whereas String is a class in java.
2. char represents a single character whereas String can have zero or more characters. So String is an array of chars.
3. We define char in java program using single quote (‘) whereas we can define String in Java using double quotes («). Since String is a special class, we get this option to define string using double quotes, we can also create a String using new keyword.

Java char to String example

We can use String.valueOf(char c) or Character.toString(char c) to convert char to string. Below is the example program showing how to use these methods to convert char to string.

public class JavaCharToString < public static void main(String[] args) < char c = 'X'; String str = String.valueOf(c); String str1 = Character.toString(c); System.out.println(c + " char converted to String using String.valueOf(char c) = " + str); System.out.println(c + " char converted to String using Character.toString(char c) = " + str1); >> 

java.lang.Character is the wrapper class for primitive char data type. Character.toString(char c) internally calls String.valueOf(char c) method, so it’s better to use String class function to convert char to String. Output of the above program is shown in below image.

Java String to char array

Since String is an array of char, we can convert a string to the char array. String class also has a method to get the char at a specific index. Let’s look at a simple program to convert String to a char array.

import java.util.Arrays; public class JavaStringToCharArray < public static void main(String[] args) < String str = "journaldev.com"; // get char at specific index char c = str.charAt(0); // Character array from String char[] charArray = str.toCharArray(); System.out.println(str + " String index 0 character = " + c); System.out.println(str + " String converted to character array = " + Arrays.toString(charArray)); >> 

To get the char from a String object, we can use chatAt(int index) method. Whereas toCharArray() returns the char array of the String. Here we are using Arrays.toString(char[] ca) method to print the char array in readable format. Output of the above program is shown below. That’s all for the char to String and String to char array conversion. Reference: Character API Doc

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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() .

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.

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.

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.

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

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.

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.

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.

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.

Conclusion

• In Java, the string is basically an object that represents a sequence of char values. An array of characters works the same as Java string.
• Strings are immutable in Java.
• A Java array is an object which contains elements of a similar data type. Arrays in Java are of fixed length.
• We can convert a String to a character array using either a naive for loop or the toCharArray() method.
• To convert a string to a string array based on a delimeter, we can use String.split() or Pattern.split() methods.
• We can also convert a string to an array containing the string as the only element by passing the string inside the curly brackets in String[] <> approach.
• To convert a list of strings in Java to a string array, we can use the toArray() method of List class.

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