Which method can be used to convert all characters in a string into a character array in Java?

Overview

In Java, a String is an object that represents the sequence of characters. To use Strings, we must first import the String class from the java.lang package. The String array is a collection of strings with a fixed length. Since arrays are immutable(cannot grow), Strings are immutable as well. Whenever a change to a String is made, an entirely new String is created.

Scope

In this Article we will discuss :

• Different ways of converting String to Character array in Java.
• Converting String to String array using 4 different methods.

We are discussing the conversion of string to array in Java, not strings or arrays specifically.

Introduction

Strings are Objects in Java that are internally supported by a char array. Strings are immutable because arrays are immutable (they can't grow). Every time you make a change to a String, a new String is produced.

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 location. Array is a data structure where we store similar elements. We can store only a fixed set of elements in a Java array.

The first element of an array is stored at the 0th0^{th} index, the second element is stored at the 1st1^{st} index, and so on.

Convert a String to Character Array in Java

There are two different ways to covert String() to Char[ ] 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.

1. Get the string.
2. Make a character array that is the same length as string.
3. Copy the character at the ithi^{th} position of the string to the ith i^{th} index of the array by traversing the string.
4. Return or perform the operation on the character array.

Using the Naive Approach, convert a String to a Character array in Java.

import java.util.*; public class MyClass { public static void main(String args[]) { String str = "Scaler"; // Given String char[] arr = new char[str.length()]; // Creating array of string length // Copy character by character into array for (int i = 0; i < str.length(); i++) { arr[i] = str.charAt(i); } // Printing the character array for (char x : arr) { System.out.println(x); } } }

Output:

2. Using toCharArray() Method

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

1. Get the string.
2. Make a character array that is the same length as string.
3. Store the array return by toCharArray() method.
4. Return or perform operation on character array.

Using the toCharArray() Method, convert a String to a Character array in Java.

import java.util.*; public class MyClass { public static void main(String args[]) { String str = "Scaler"; // Creating array of string and Store the array return by toCharArray() method. char[] arr = str.toCharArray(); // Printing the character array for (char x : arr) { System.out.println(x); } } }

Output:

Converting String to String Array in Java

We'll learn how to convert a string to array 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.

public class SplitMethod { public static void main(String[] args) { //declaring and initializing a string String str = "Using the split() method to convert a string to array in Java "; String[] arr = null; //declaring an empty string array //converting using String.split() method with whitespace as a delimiter arr = str.split(" "); //printing the converted string array for (int i = 0; i< arr.length; i++) { System.out.println(arr[i]); } } }

Output:

Using the Pattern.split() method to convert a string to array in Java

Example 2: We changed the string to array in Java in the following example using the delimiter, which is a , (comma).

public class SplitMethod { public static void main(String[] args) { //declaring and initializing a string String str = "What,is,your,name ?"; String[] arr = null; //declaring an empty string array //converting using String.split() method with comma(,) as a delimiter arr = str.split(","); //printing the converted string array for (int i = 0; i< arr.length; i++) { System.out.println(arr[i]); } } }

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 must first import the Pattern class into our Java code as follows:

import java.util.regex.Pattern;

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

//importing Pattern class import java.util.regex.Pattern; public class PatternSpiltmethod { public static void main(String[] args) { //declaring and initializing a string String str = "Using the Pattern.split() method to convert a string to array in Java "; //declaring an empty string array String[] arr = null; //parsing white space as a parameter Pattern ptr = Pattern.compile(" "); //storing the string elements in array after splitting arr = ptr.split(str); //printing the converted string array for (int i = 0; i< arr.length; i++) { System.out.println(arr[i]); } } }

Output:

Using the Pattern.split() method to convert a string to array in Java

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

//importing Pattern class import java.util.regex.Pattern; public class PatternSpiltmethod { public static void main(String[] args) { //declaring and initializing a string with a separator String str = "What&qais&qayour&qaname ?"; //declaring an empty string array String[] strArray = null; //splitting the string with delimiter as #a1 String patternStr = "&qa"; Pattern ptr = Pattern.compile(patternStr); //storing the string elements in array after splitting strArray = ptr.split(str); //printing the converted string array for (int i = 0; i< strArray.length; i++) { System.out.println(strArray[i]); } } }

Output:

Using String[ ] Approach

We can simply convert string to string array by using the string index [ ]. Here, we pass the string to String [ ] {}.

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

import java.util.Arrays; public class StringtoStringArray { public static void main(String[] args) { //declaring and initializing a string String str = "Using the String[] method to convert a string to array in Java"; //passing the string to String[] {} String[] arr = new String[] {str}; //printing the string array using Arrays.toString() System.out.println(Arrays.toString(arr)); } }

Output

[Using the String[] method to convert a string to array in Java]

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 a string array.

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

//importing ArrayList and List class import java.util.ArrayList; import java.util.List; public class StringListtoArray { public static void main(String[] args) { //creating a list of type string List list = new ArrayList (); //adding elements to list list.add("What"); list.add("is"); list.add("your"); list.add("name ?"); //size of list int list_size = list.size(); //creating string array String[] arr = new String[list_size]; //converting to string array list.toArray(arr); //printing the string array for(int i = 0; i < arr.length; i++) { System.out.println(arr[i]); } } }

Output

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.
• A Java array is an object which contains elements of a similar data type.
• We use the standard iterative method to convert string to char array in java.
• We also learned how to convert string to char array in java by using toCharArray() method.
• We learned how to convert string to array in java using 4 different methods.