Java Tutorial



Java Tutorial

String Length in Java


When working with strings in Java, one of the most typical requirements is to determine the length of the string. Understanding how to obtain the length of a string is vital, whether you need to validate user input, alter text, or conduct a variety of string operations. In this piece, we will go into the nitty-gritty details of string length in Javascript. We will also discuss the many methods to retrieve it and provide examples of real-world applications to help you better grasp the concepts.


In Java programming, strings serve an essential purpose by enabling programmers to do textual data manipulation in an effective manner. In the following part, we will investigate the concept of strings in Java as well as the many methods that may be used to construct string objects.

What Is a String in Java?

A string is an essential data type in Java. It can be thought of as a representation of a string of characters. Textual information can be stored inside it and manipulated after it has been encased in double-quotes. The validation of user input, the processing of user data, and the generation of output are all examples of the widespread use of strings in Java programming. This highlights the significance of strings in the language.

It is possible for a string to contain any combination of characters, including letters, numbers, symbols, and even blank space between the characters. It is possible for it to represent single words, complete sentences, entire paragraphs, or even an entire document. Concatenation, substring extraction, search, and replace are just some of the string-related operations that may be performed thanks to the extensive feature set and method collection that Java offers for working with strings.

How to Create a String Object?

In Java, there are two ways to create a string object: using a string literal or the `new` keyword.

Using String Literal

The most common and convenient way to create a string is by using a string literal. A string literal is a sequence of characters enclosed in double-quotes. For example:

Here, the string literal `"Hello, World!"` is assigned to the variable `greeting`.

Using the new Keyword

Another way to create a string object is by using the `new` keyword along with the `String` class constructor. For example:

In this case, the `new` keyword creates a new instance of the `String` class and assigns the value `"John Doe"` to the variable `name`.

It's important to note that using the new keyword explicitly creates a new string object, even if a string with the same value already exists in the string pool. Therefore, it is recommended to use string literals whenever possible for efficiency and better memory management.

Understanding the concept of strings and the different ways to create string objects sets the foundation for exploring string length and its significance in Java programming. In the following sections, we will delve into the details of determining string length and demonstrate its practical usage through examples.

String length in Java W3schools

Now that we have a good understanding of strings in Java, let's explore different methods to determine their length.


The length of a string in Java can be obtained using the `length()` method. The method signature is as follows:

Specified by

The `length()` method is specified by the `CharSequence` interface, which is implemented by the `String` class.


The `length()` method returns the number of characters in the string as an integer value.

  • Java String Length Return Value

The return value of the `length()` method is always a non-negative integer representing the length of the string. If the string is empty, the return value is 0.

Internal Implementation

The 'length()' method is responsible for storing and retrieving the length of the string by making use of an integer field that is contained inside the 'String' class. This eliminates the need for traversal or computation, which ensures that the length of information can be accessed quickly and easily.

Methods of Java strings

In addition to the string length() method, Java provides a rich set of methods to perform various operations on strings. Some commonly used methods include `charAt()`, `substring()`, `concat()`, and `replace()`. These methods enable string manipulation, extraction, concatenation, and substitution, among other functionalities.

  • What Is the Method Used to Find String Length in Java?

The `length()` method is the recommended approach to finding the length of a string in Java. Let's explore a few examples to see it in action.

Example 1:



In this example, the text string is passed to the length() method. It returns 13 as the number of characters in the string. The output is then displayed on the console.

Example 2:



In this example, the length() method is called on an empty string ‘emptyString’. Since the string has no characters, the method returns 0.

Example 3:



In this example, a null string is assigned to ‘nullableString’. Before calling the length() method, a null check is conducted to avoid a ‘NullPointerException’. Given that the string is null, the program outputs "String is null."

Example 4:



In this example, the string ‘unicodeString’ contains a Unicode character representation for the heart symbol (\u2764). The length() method correctly counts the Unicode character as a single character, resulting in a length of 7.

These examples demonstrate how the length() method can be used to determine the length of a string in Java, regardless of whether the string is empty, non-empty, or contains Unicode or undefined characters.

Finding String Length in Java Using Length (): Use If and Else statements

Alternatively, you can use conditional statements to find the length of a string without using the `length()` method. 

Here's an example:


Concatenating Strings

String concatenation is a common process, and Java provides several methods for accomplishing it. One of the simplest methods is using the `+` operator or the `concat()` method.



Escape Character (\) in Java Strings

Java strings support escape characters to represent special characters or sequences. Some commonly used escape characters include `\"` for double quotes, `\'` for single quotes, `\\` for backslashes, and `\n` for newlines.



Java Strings: Mutable or Immutable

In Java, strings are immutable, which means that the values to which they are assigned cannot be changed. Any action that gives the impression of changing the contents of a string actually leads to the production of a brand-new string object. This immutability promotes efficient memory management and ensures the integrity and consistency of strings in situations with multiple threads. Because concatenating strings is such a popular operation, Java has a number of different methods that can be used for the process.

String Array Length in Java

In addition to individual strings, Java also allows working with arrays of strings. To determine the length of a string array, you can use the `length` property. For example:



In Java, understanding and utilizing string length is a crucial aspect of effective string manipulation. By leveraging the `length()` method provided by the `String` class, you can effortlessly obtain the Java string size in bytes and utilize it in various scenarios within your Java programs.

By using the `length()` method, you can determine the number of characters in a string, allowing you to validate input lengths, extract substrings based on specific criteria, or perform conditional operations. This method returns an integer value representing the string length online, allowing you to dynamically adapt your code based on the size of the string.

In addition to the `length()` method, being familiar with other string methods and their functionalities expands your capabilities for string processing and manipulation. Java provides a rich set of string manipulation methods, such as concatenation, substring extraction, searching, replacing, and formatting. These methods empower you to perform complex string operations efficiently, making your code more concise and readable.

Moreover, understanding the internal implementation of strings and their immutability in Java allows you to design more efficient algorithms and optimize memory usage. The immutability of strings ensures their integrity and consistency, making them suitable for multithreaded environments and facilitating efficient memory management.

In conclusion, having a comprehension of string length and how to set string length in Java empowers you to confidently work with strings and perform a wide array of operations. Whether you need to validate input, extract specific parts of a string, or manipulate text-based data, the `length()` method and other string manipulation methods provide powerful tools to achieve your goals. By effectively leveraging these capabilities, you can write robust, efficient, and maintainable Java code. So, continue exploring the vast functionalities of strings in Java and unlock the full potential of string manipulation in your programming endeavors.


1. How to calculate the length of string in Java without using length()?

In Java, you can calculate the length of a string without using the length() method by using a for loop or while loop to iterate over the characters in the string. Here's an example of how you can do this:

2. What kind of return value does the 'length()' function in Java produce?

A string's length can be determined by calling the 'length()' method, which then returns an integer value.

3. Are strings allowed to be changed in Java?

Strings in Java cannot be changed in any way. After they have been created, their values cannot be changed in any way. On the other hand, new strings can be generated using operations such as concatenation and others.

4. In Java, what are some ways that strings can be joined together?

You can concatenate strings in Java by using either the '+' operator or the 'concat()' function. Both of these options are available to you. For example, "String fullName = firstName +'+ lastName;" or "String fullName = firstName.concat(" ").concat(lastName);" are both valid expressions.

5. How can I find out how much space an entire Java string array takes up?

Java's 'length' property can be utilized to determine the size of a string array in the programming language. For example, the expression "int arrayLength = fruits.length;" returns the length of the string array "fruits." Other examples are "int arrayLength = fruits.length;" and "fruits.length;"

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