Scanner Class in Java

Scanner is a predefined class in Java used to take input from the user. It is present in the java.util package and supports different types of input such as integers, strings, float values, and characters. The Scanner class makes input handling simple and user-friendly in Java programs.

• Used to read user input from keyboard.
• Supports different data types like int, double, String, etc.
• Uses methods such as nextInt(), nextLine(), and nextDouble().

Example: Java program to demonstrate the use of Scanner class to take input from user

Output:

Explanation: In the above code example, we use the nextLine() of Scanner class to read the line value which is entered by the user and print it in the console.

Steps To Use Scanner Class to Take Input

Step 1: Import Scanner Package

Import the java.util.Scanner package at the beginning of the program.

import java.util.Scanner
public class Geeks{
public static void main(String [] args){
}
}

Step 2: Create Scanner Object

Scanner sc = new Scanner (System.in);

Here "sc" is an object of the Scanner class. We can give it different names for our ease such as in, var or obj etc. Using this object we can use the methods of the Scanner class.

Step 3: Take Integer Input

int age = sc.nextInt();

Scanner Input Types

The scanner class helps take the standard input stream in Java. So, we need some methods to extract data from the stream. The methods used for extracting data are mentioned below:

Let us look at the code snippet to read data of various data types.

Example 1: Java program to read data of various types using Scanner class

Output:

Explanation: In the above code example, we use the Scanner class to take different types of input values from user and print it in the console.

• hasNextInt(): This method is used to check if the token is an integer.
• hasNextLine(): This method is used to check if there is an input in next line.
• useDelimiter(): This method changes the default whitespace delimiter.

Example 2: Java program to read some values using Scanner class and print their mean.

Output:

Explanation: In the above code example, we use the hasNext() and hasNextInt() method to take the input values from user and then user give the input value they can specify that the input value is ended and they can type "done" to find the mean value of given input.

Important Points about Scanner Class

• System.in is used for keyboard input; File object is used for file input.
• Use nextXYZ() methods for numeric inputs like nextInt(), nextShort(), etc.
• Use nextLine() to read a full string/line.
• Use next().charAt(0) to read a single character.
• Always close the Scanner object after use.
• Scanner reads input as tokens (words separated by spaces). Example: "How are you" -> "How", "are", "you".