Introduction

In the java.util package, there is a class called Scanner that is used to collect user input. scanner class in Java, Create an instance of the Scanner class and call any of the various methods listed in the class documentation to access the class. The need to solicit user input arises frequently when we are coding. This may be accomplished in Java by utilizing the Scanner class, which accepts inputs of all built-in data types like boolean, int, etc.

What is Scanner Class in JAVA?

Scanner Class in JAVA, which is part of the java.util package is mostly used to collect user input. You can build an object of the Scanner class and employ any of the class methods to use the class.

In the java.util package, there is a class called scanner that is used to get input from strings and primitive types like int, double, etc. scanner class in Java, It is the simplest way to read input in a Java program, however, it is not the most effective if you need an input method for situations where time is a factor, like in competitive programming. To know more about data science course pune

How to import Scanner Class in Java?

The Scanner class can be found in the java.util package, as is already known. Consequently, we must first import the Scanner class from its package before using it:

import java.util.Scanner

import the java.util package.Meaning of the scanner is that, as desired, we are importing the Scanner class from java.util package.

Create a Scanner object

Our next action is to build a Scanner object after importing the Scanner class. 

The general syntax is as follows to do that: 

Scanner object_name = new Scanner(InputStream input);

OR

Scanner object_name = new Scanner(String str);

Reading the User Input

We can now read the user input as follows now that we have imported the scanner class, scanner class in Java, created a scanner object, and are aware of the methods available to the scanner class:

data_type variable_name = object_name.scanner_class_method;

Important Methods of Scanner Class in JAVA

Let’s examine some of the Scanner classes in JAVA methods that are most frequently utilized.

• useDelimiter(String pattern) – the scanner’s delimiter to be applied. the delimiter by default is whitespace.
• hasNext() – if there is another token in the input, it returns true. Because it uses blocking, it will continuously wait for user input.
• next() – the following token from the scanner is returned. It is utilized along with the hasNext() method.
• close() – Use this technique to shut down the scanner and free up system resources once you’re done using it because it uses a lot of resources.

Steps to Initialize and Use Scanner

• Utilizing the correct constructor for the input type, scanner class in Java, such as InputStream, File, or String, is the first step in initializing the scanner class. Set the character set and delimiter to be used, if necessary.
• The hasNext() method’s second step is to wait for the input token.
• Next, read each token and process it individually using the next() method.

How Does Scanner Work?

• The delimiter pattern supplied by the Scanner class is used to separate the input into tokens.
• To read and analyze each token individually, use the next() method.
• To free up system resources, close the Scanner instance last.

Java Scanner Regular Expression Example

Example-1

Let’s imagine we wish to process only the integers included in a string source. scanner class in Java, In order to handle tokens, we can utilize the scanner with the non-digit regex to only retrieve integers.

Code

//using regex to read only integers from a string source

String data = “1a2b345c67d8,9#10”;

Scanner sc1 = new Scanner(data);

// setting non-digit regex as a delimiter

sc1.useDelimiter(“\D”);

while(sc1.hasNext()) {

System.out.println(sc1.next());

}

// don’t forget to close the scanner

sc1.close();

Output

1

2

345

67

8

9

10

Example-2

Consider a code that requests and stores data about a user’s name, age, salary, and mood. We will need to utilize the Scanner class because we are receiving input from the user. Click here to know about best data science training institute in Pune

Code

import java.util.Scanner;     //importing Scanner class

public class Main

{

public static void main(String args[])

{

          Scanner sc=new Scanner(System.in);     //creating scanner object

          System.out.print(“Enter your full name: “);

          String name = sc.nextLine();     //String input

          System.out.print(“Enter your age: “);

          int age = sc.nextInt();     //integer input

          System.out.print(“Enter your salary: “);

          double salary = sc.nextDouble();     //double-type input

          System.out.print(“Are you happy today? True/False: “);

          boolean mood = sc.nextBoolean();     //boolean input

          System.out.println();

          System.out.println(“Name: “+name+”nAge: “+age+”nSalary: “+salary+”nHappy? “+mood);

}

}

Advantages of Scanner Class in JAVA

The benefits of Scanner Class in JAVA are:

1. A unique token can be used to identify the end of the data piece.
2. It parses the read data into predetermined kinds, such as short, int, float, boolean, etc.
3. It can read both primitive data types and strings.
4. Because each word can be retrieved as a token and treated separately, sting manipulation is simpler.

Drawbacks of Scanner Class in JAVA

The disadvantages you may face with
the Scanner class in JAVA are:

1. The class Scanner is not thread-safe.
2. It has a smaller (1KB) buffer memory.
3. Since the Java Scanner Class parses the underlying data stream slowly, it is unable to support rapid I/O in Java.
4. There is no synchronization. 
5. JDK 1.5 or later is the only version that supports the Scanner class.

Conclusion

A Java utility class called Scanner may read human input or do straightforward regex-based parsing of file or string sources. data types in javascript, However, for better speed in real-world applications, scanner class in Java, it is preferable to use CSV parsers rather than the Scanner class to parse CSV data. Scanner class was explained to us. scanner class in Java, The easiest way to receive input in Java is through the Scanner class, which has several methods (described above). Due to its straightforward logic and usage, you can use it when you don’t have much time to write the code quickly.

Frequently Asked Questions