Scanner Class in Java

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What is the use of Scanner Class in Java?

The Scanner class in Java is a simple text scanner that can be used to parse primitive types and strings using regular expressions. It is the easiest way to get input from the user in a Java program.

The Scanner class is located in the java.util package. To create an object of the Scanner class, you can use the following code:

Scanner scanner = new Scanner(System.in);

The System.in object represents the standard input stream, which is the keyboard by default. You can also pass an object of the File class to the Scanner constructor to read input from a file.


 

How Scanner Class Reads Input

The Scanner class provides a number of methods for reading input. The most commonly used methods are:

  • nextInt(): Reads the next integer from the input stream.
  • nextDouble(): Reads the next double from the input stream.
  • next(): Reads the next token from the input stream. A token is a sequence of characters separated by whitespace.
  • nextLine(): Reads the next line from the input stream.

The Scanner class also provides methods for reading strings, characters, and boolean values.

Here is an example of how to use the Scanner class to read an integer from the user:

int number = scanner.nextInt();

This code will read the next integer from the input stream and store it in the variable number.

Here is an example of how to use the Scanner class to read a string from the user:

String name = scanner.next();

This code will read the next token from the input stream and store it in the variable name.

The Scanner class also provides methods for skipping whitespace, ignoring case, and parsing regular expressions.

Advantages of using the Scanner class

  • It is easy to use.
  • It supports a variety of data types.
  • It can be used to read input from a variety of sources, including the keyboard, a file, or a network connection.

Disadvantages of using the Scanner class

  • It can be inefficient if you need to read a large amount of input.
  • It is not thread-safe, so you cannot use it in a multithreaded environment.

Overall, the Scanner class is a versatile and easy-to-use tool for getting input from the user in Java. It is a good choice for most applications that need to read input from the user.

Here are some additional tips for using the Scanner class:

  • Use the hasNext() method to check if there is more input available before calling the next() method. This will prevent the next() method from throwing an exception if there is no more input available.
  • Use the skip() method to skip over whitespace or other characters that you do not want to read.
  • Use the useDelimiter() method to specify a custom delimiter pattern. This can be useful if you want to read input that is not separated by whitespace.

I hope this blog post has been helpful. If you have any questions, please feel free to ask it in the comments section provided below. For more information on the Scanner class, wait for our next post on Scanner Class in Java.

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