Difference Between next() and nextLine() Methods in Java

Java next() Method

The next() method in java is present in the Scanner class and is used to get the input from the user. In order to use this method, a Scanner object needs to be created. The method can read the input only until a space(" ") is encountered. In other words, it finds and returns the next complete token from the scanner.

next() can read the input only till the space. It cannot read two words separated by a space. Also, next() places the cursor in the same line after reading the input.

NextMethod.java

import java.util.Scanner;
class NextMethod {
	public static void main(String[] args)
	{
		// Creating the Scanner object
		Scanner sc = new Scanner(System.in);
		// Use of the next() method
		String input = sc.next();
		System.out.println(input);
	}
}

Input

First line
Second line

Output:

First

Java nextLine() Method

The nextLine() in Java is a method of the java.util.Scanner class. It reads the input string unless the line changes or a new line and then ends the input with \n or pressing enter. Usually, if we are taking any other type of input like int or String word input with the next() method before the nextLine() method we usually add an extra nextLine() method just before the nextLine() method, otherwise the nextLine() method will return a blank String. Another way would be to always use nextLine() wrapped into an Integer.parseInt().

The method does not accept any parameter. It returns the value in the string it returns the current line that was skipped.

Exceptions

The nextLine() in Java throws two types of exceptions:

NoSuchElementException: The nextLine() method throws NoSuchElementException exception when there is no line found in the input.
IllegalStateException: The method throws IllegalStateException exception if this scanner class is closed. When a Scanner is closed, it will close its input source if the source implements the Closeable interface. And the interface will no longer be able to take input from the user.

Example of nextLine() Method

In this following code, we will see how the nextLine() method reads the input string unless the line changes or a new line and then ends the input with \n or pressing enter and keep the next line input as a buffer for the next method.

NextLine.java

import java.util.*;  
public class NextLine {
    public static void main(String[] argv)
        throws Exception
    {
        String s = "Hello \n World \n Hello World";
        // create a new scanner
        // with the specified String Object
        Scanner scanner = new Scanner(s);
        // print the next line
        System.out.println(scanner.nextLine());
        // print the next line again
        System.out.println(scanner.nextLine());
        // print the next line again
        System.out.println(scanner.nextLine());
        scanner.close();
    }
}

Output:

Hello
 World
 Hello World

Let's see another example.

NextLineExample.java

import java.util.Scanner;
public class NextLineExample {
	public static void main(String[] argv)
		throws Exception
	{
		// create a new scanner
		Scanner sc = new Scanner(System.in); 
        // storing an integer from the input
        int x = sc.nextInt(); 
        // storing a word for fthe rom input
        String word = sc.next(); 
        // extra nextLine() method to 
       absorborbe the extra change in line
        sc.nextLine();   
        String s = sc.nextLine();
        System.out.println("Integer value is : "+x);
        System.out.println("String word value is : "+word);
        System.out.println("String next line value is : "+s);
	}
}

Output:

10
Hello
World

Output:

The integer value is : 10
String word value is : Hello
String next line value is : World

Internal Working of nextLine() Method in Java?

The nextLine() in Java is a method of the java.util.Scanner class. It is used to store the user input value of the String type. Before implementing this method to obtain the user's input, it is necessary to construct a Scanner object. The main purpose of the method is that it reads the input up till the end of the line. It reads the input string unless the line changes or a new line and then ends the input with \n or pressing enter.

Since nextLine() in Java, while looking for a line separator continues to read through the input, it may buffer all of the input reading for the line to ignore if there are no line separators present. nextLine() reads input including space between the words (that is, it reads till the end of line \n). Once the input is read, nextLine() positions the cursor in the next line.

Java next() Vs. nextLine() Method

next() Method	nextLine() Method
It usually reads the single word input from the user in a String or up to the input reaches the character space.	This method usually reads the input from the user until the next line.
It cannot read the words with blank spaces.	This method can read the words with blank spaces.
After getting a blank space, the method stops reading input.	Once there is a line separator \n or pressing enter, this method stops reading the input, but it will read the blank spaces.
After receiving input, the cursor is placed in the same place or the same line.	After receiving input, the cursor is placed on the next line.
The escapes sequence that the next() refers to space.	The escapes sequence that the nextLine() refers to is line separator /n.
Example : For String "Hello World" the next() method will read only the "Hello" word.	Example : For String "Hello World" the nextLine() method will read the "Hello World" word.