What Is String?

String and how to use it

In Java, a String is a data type used to represent text. Its syntax looks like this:

Main


              1
            
String name = "string";

You've already encountered a String when you displayed something on the screen using double quotation marks (""). A string can also be output like any other variable, for example:

Main


              12345678910
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing a String variable
        String hello = "Hello world!"; 
        // Printing the String variable
        System.out.println(hello);
    }
}

Let's move on to the challenging part then. A string is a data type that cannot be changed after initialization. This is called an immutable class. Don't get stuck on these intimidating words right now; we will discuss them in a separate course. We can directly modify the value of an already initialized string variable, but in doing so, we simply create a new object in memory. For example:

Main


              123456789101112
            
package com.example;

public class Main {
    public static void main(String[] args) {
        // Initializing a String variable
        String hello = "Hello world!"; 
        // Changing the reference to a new object in heap memory
        hello = "Hello c<>definity";        
        // Printing the updated String variable
        System.out.println(hello);
    }
}

We can also create arrays of strings:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        String[] array = {"Hello", ", ", "c<>definity"};
        for (String element : array) {
            System.out.print(element);
        }
    }
}

Structure of a string

In Java, strings are sequences of characters stored as objects of the String class. Each character in a string is assigned a specific position, called an index, starting from zero. This makes it easy to access individual characters, manipulate them, and perform operations like extracting substrings.

The image illustrates how the string "Codefinity" is broken down into characters with their corresponding indices. Indexing starts at zero, where C is at index 0, and the last character, y, is at index 9.

This structure makes it easy for developers to work with individual characters in a string using methods from the String class, which we will explore in the next chapter.

1. Will the following code compile?

2. Can we create an array of `String` data type?

Everything was clear?

Thanks for your feedback!

Section 5. Chapter 1

Java Basics

What Is String?

String and how to use it

Structure of a string

1. Will the following code compile?

2. Can we create an array of String data type?

2. Can we create an array of `String` data type?