Java Scanner

Scanner class in Java is found in the java.util package. Java provides various ways to read input from the keyboard, the java.util.Scanner class is one of them.

The Scanner input in Java should be of primitive data types, such as int, float, double, etc., and string types.

The package of the Scanner class – java.util.Scanner, needs to be imported to use the Scanner class.

            import java.util.Scanner;

To use the Scanner class, create an object of the class and use any of the available methods found in the Scanner class.

Object to read from file

Scanner obj1 = new Scanner(File filename);

Object to read from the input stream

Scanner obj2 = new Scanner(inputStream inputStreamName);

Object to read input as String

Scanner obj3 = new Scanner(String s);

Java Scanner Class Methods

SN	Modifier & Type	Method	Description
1)	void	close()	It is used to close this scanner.
2)	pattern	delimiter()	It is used to get the Pattern which the Scanner class is currently using to match delimiters.
3)	Stream<MatchResult>	findAll()	It is used to find a stream of match results that match the provided pattern string.
4)	String	findInLine()	It is used to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.
5)	string	findWithinHorizon()	It is used to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.
6)	boolean	hasNext()	It returns true if this scanner has another token in its input.
7)	boolean	hasNextBigDecimal()	It is used to check if the next token in this scanner's input can be interpreted as a BigDecimal using the nextBigDecimal() method or not.
8)	boolean	hasNextBigInteger()	It is used to check if the next token in this scanner's input can be interpreted as a BigDecimal using the nextBigDecimal() method or not.
9)	boolean	hasNextBoolean()	It is used to check if the next token in this scanner's input can be interpreted as a Boolean using the nextBoolean() method or not.
10)	boolean	hasNextByte()	It is used to check if the next token in this scanner's input can be interpreted as a Byte using the nextBigDecimal() method or not.
11)	boolean	hasNextDouble()	It is used to check if the next token in this scanner's input can be interpreted as a BigDecimal using the nextByte() method or not.
12)	boolean	hasNextFloat()	It is used to check if the next token in this scanner's input can be interpreted as a Float using the nextFloat() method or not.
13)	boolean	hasNextInt()	It is used to check if the next token in this scanner's input can be interpreted as an int using the nextInt() method or not.
14)	boolean	hasNextLine()	It is used to check if there is another line in the input of this scanner or not.
15)	boolean	hasNextLong()	It is used to check if the next token in this scanner's input can be interpreted as a Long using the nextLong() method or not.
16)	boolean	hasNextShort()	It is used to check if the next token in this scanner's input can be interpreted as a Short using the nextShort() method or not.
17)	IOException	ioException()	It is used to get the IOException last thrown by this Scanner's readable.
18)	Locale	locale()	It is used to get a Locale of the Scanner class.
19)	MatchResult	match()	It is used to get the match result of the last scanning operation performed by this scanner.
20)	String	next()	It is used to get the next complete token from the scanner which is in use.
21)	BigDecimal	nextBigDecimal()	It scans the next token of the input as a BigDecimal.
22)	BigInteger	nextBigInteger()	It scans the next token of the input as a BigInteger.
23)	boolean	nextBoolean()	It scans the next token of the input into a boolean value and returns that value.
24)	byte	nextByte()	It scans the next token of the input as a byte.
25)	double	nextDouble()	It scans the next token of the input as a double.
26)	float	nextFloat()	It scans the next token of the input as a float.
27)	int	nextInt()	It scans the next token of the input as an Int.
28)	String	nextLine()	It is used to get the input string that was skipped of the Scanner object.
29)	long	nextLong()	It scans the next token of the input as a long.
30)	short	nextShort()	It scans the next token of the input as a short.
31)	int	radix()	It is used to get the default radix of the Scanner use.
32)	void	remove()	It is used when remove operation is not supported by this implementation of Iterator.
33)	Scanner	reset()	It is used to reset the Scanner which is in use.
34)	Scanner	skip()	It skips input that matches the specified pattern, ignoring delimiters
35)	Stream<String>	tokens()	It is used to get a stream of delimiter-separated tokens from the Scanner object which is in use.
36)	String	toString()	It is used to get the string representation of Scanner using.
37)	Scanner	useDelimiter()	It is used to set the delimiting pattern of the Scanner which is in use to the specified pattern.
38)	Scanner	useLocale()	It is used to sets this scanner's locale object to the specified locale.

 

 

Ex 1:

import java.util.*; 

public class ScannerExample { 

public static void main(String args[]){ 

          Scanner in = new Scanner(System.in); 

          System.out.print("Enter your name: "); 

          String name = in.nextLine(); 

          System.out.println("Name is: " + name);            

          in.close();            

          } 

} 

Ex 2:

import java.util.*; 

public class ScannerClassExample1 {   

      public static void main(String args[]){                      

          String s = "Hello"; 

          Scanner scan = new Scanner(s); 

          //Check if the scanner has a token 

          System.out.println("Boolean Result: " + scan.hasNext()); 

          //Print the string 

          System.out.println("String: " +scan.nextLine()); 

          scan.close();          

          System.out.println("--------Enter Your Details-------- "); 

          Scanner in = new Scanner(System.in); 

          System.out.print("Enter your name: ");   

          String name = in.next();  

          System.out.println("Name: " + name);          

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

          int i = in.nextInt(); 

          System.out.println("Age: " + i); 

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

          double d = in.nextDouble(); 

          System.out.println("Salary: " + d);        

          in.close();          

          }   

}