What is a string?

A string is a sequence or array of characters, In Java, The string is an immutable object that means it is constant and can not be changed once it has been created.

To work with string java has a built-in class ‘String’ that provides dozen of methods to deal with a string.

How to create a string in java?

There are two ways to create a string in Java –

1. Using string literal
2. Using the new keyword

Using string literal

The Java string literal can be created using double quotes.

Example

public class StringExample1 {

    public static void main(String[] args) {

        // Using string literal
        String str = "Hello World!";

        // Printing the string
        System.out.println(str);

    }
}

Using the new keyword

The Java string literal can be created using the ‘new’ keyword.

Example

public class StringExample2 {

    public static void main(String[] args) {

        // Using string literal
        String str = "Hello World!";

        // Using new keyword
        String myStr = new String("I, am a string\nThis is second line.");

        // Printing the string
        System.out.println(str);
        System.out.println(myStr);

    }
}

String constants pool

The Java string constant pool is a special memory area where literal string values are stored. Whenever we create a string literal, the JVM checks the “string constant pool” for the already existing string with the same value in the pool. If the string with the same value exists, a reference to the pooled instance is returned otherwise, new string instance is created and added into the pool.

Java String methods