String to arr java

How to Convert a String to an Array in Java

Java makes it easy to convert a string to an array by providing the built-in .split() method on the String object.

The challenge#

Write a function to split a string and convert it into an array of words. For example:

"Robin Singh" ==> ["Robin", "Singh"] "I love arrays they are my favorite" ==> ["I", "love", "arrays", "they", "are", "my", "favorite"] 

The solution in Java code#

This is a really simple one, you just split the string with the space character:

However, if you prefer not to use the space character, you can opt for using \\s+ instead:

Test cases to validate our Java solution#

import org.junit.Test; import static org.junit.Assert.assertArrayEquals; import org.junit.runners.JUnit4; public class SolutionTest < @Test public void basicTests() < assertArrayEquals(new String[], Solution.stringToArray("Robin Singh")); assertArrayEquals(new String[], Solution.stringToArray("I love arrays they are my favorite")); > > 

Building additional test cases#

import org.junit.Test; import static org.junit.Assert.assertArrayEquals; import org.junit.runners.JUnit4; public class SolutionTest < @Test public void basicTests() < assertArrayEquals(new String[], Solution.stringToArray("Robin Singh")); assertArrayEquals(new String[], Solution.stringToArray("I love arrays they are my favorite")); > @Test public void randomTests() < for(int i = 0; i < 200; i++)< String testString = makeString(0,30); assertArrayEquals(randomTest(testString), Solution.stringToArray(testString)); >> private String makeString(int min, int max) < StringBuilder sb = new StringBuilder(); int length = (int)Math.ceil((Math.random() * max) + min); for (int i = 0; i < length; i++) < sb.append(makeWord(min, max)); if (i < length-1) sb.append(" "); >return sb.toString(); > private String makeWord(int min, int max) < StringBuilder sb = new StringBuilder(); String possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"; int length = (int)Math.ceil((Math.random() * max) + min); for(int i = 0; i < length; i++) < sb.append(possible.charAt((int)Math.floor(Math.random() * possible.length()))); >return sb.toString(); > private String[] randomTest(String s) < return s.split(" "); >> 

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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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String to arr java

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How to Convert String to Array in Java

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.

Sometimes we have to split String to array based on delimiters or some regular expression. For example, reading a CSV file line and parsing them to get all the data to a String array. In this tutorial, we will learn how to convert String to Array in Java program.

String to Array in Java

String class split(String regex) can be used to convert String to array in java. If you are working with java regular expression, you can also use Pattern class split(String regex) method. Let’s see how to convert String to an array with a simple java class example.

package com.journaldev.util; import java.util.Arrays; import java.util.regex.Pattern; public class StringToArrayExample < /** * This class shows how to convert String to String Array in Java * @param args */ public static void main(String[] args) < String line = "My name is Pankaj"; //using String split function String[] words = line.split(" "); System.out.println(Arrays.toString(words)); //using java.util.regex Pattern Pattern pattern = Pattern.compile(" "); words = pattern.split(line); System.out.println(Arrays.toString(words)); >> 

[My, name, is, Pankaj] [My, name, is, Pankaj] 

Note that Java provides a legacy class StringTokenizer also but you should not use it because it doesn’t have an option for a regular expression and using it is confusing. We can use Java regular expressions also to split String into String array in java, learn more about java regular expression.

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