The Java Scanner class is widely used to parse text for strings and primitive types using a regular expression. It is the simplest way to get input in Java. By the help of Scanner in Java, we can get input from the user in primitive types such as int, long, double, byte, float, short, etc.

Why do we use scanners in Java?

Scanner is a class in java. util package used for obtaining the input of the primitive types like int, double, etc. and strings. It is the easiest way to read input in a Java program, though not very efficient if you want an input method for scenarios where time is a constraint like in competitive programming.

What is the Scanner class and why is it used?

What is the Scanner class? The Scanner class is mainly used to get the user input, and it belongs to the java. util package. In order to use the Scanner class, you can create an object of the class and use any of the Scanner class methods.

What is the syntax of scanner in Java?

5) Java Scanner Class Methods

Method Scanner in Java Syntax
nextDouble() Scanner.nextDouble()
nextFloat() Scanner.nextFloat()
nextInt() Scanner.nextInt() Scanner.nextInt(int radix)
nextLine() Scanner.nextLine()

What is the use of scan nextLine () in Java?

The nextLine() method of the java. util. Scanner class scans from the current position until it finds a line separator delimiter. The method returns the String from the current position to the end of the line.

Why do we scanner?

Scanners work by converting the image on the document into digital information that can be stored on a computer through optical character recognition (OCR). This process is done by a scanning head, which uses one or more sensors to capture the image as light or electrical charges.

What is nextInt () in Java?

nextInt() method Scans the next token of the input as an int.An invocation of this method of the form nextInt() behaves in exactly the same way as the invocation nextInt(radix), where radix is the default radix of this scanner.

What is scanner input or output?

A computer scanner is a digitizer, which is a type of input device. It takes real-world objects (e.g., a document or picture) and converts them to digital information for a computer to store or manipulate.

Can you have two scanners in Java?

Having multiple scanners (on same stream) is a very bad practice, because scanners consume the stream they share. I’ve verified it while debugging the Scanner class source code, and there I’ve found: a reference to the source input stream. a internal private buffer used to hold input.

How do I scan an int in Java?

Example of integer input from user

  1. import java.util.*;
  2. class UserInputDemo.
  3. {
  4. public static void main(String[] args)
  5. {
  6. Scanner sc= new Scanner(; // is a standard input stream.
  7. System.out.print(“Enter first number- “);
  8. int a= sc.nextInt();

What is a scanner class in Java?

The Scanner class is used to get user input, and it is found in the java. util package. To use the Scanner class, create an object of the class and use any of the available methods found in the Scanner class documentation.

What does scanner next () do?

next() method finds and returns the next complete token from this scanner. A complete token is preceded and followed by input that matches the delimiter pattern. This method may block while waiting for input to scan, even if a previous invocation of hasNext() returned true.

What is next () and nextLine () in Java?

next() can read the input only till the space. It can’t read two words separated by a space. Also, next() places the cursor in the same line after reading the input. nextLine() reads input including space between the words (that is, it reads till the end of line \n ).

What is hasNext () in Java?

The hasNext() method checks if the Scanner has another token in its input. A Scanner breaks its input into tokens using a delimiter pattern, which matches whitespace by default. That is, hasNext() checks the input and returns true if it has another non-whitespace character.

What is nextLong in Java?

nextLong() method scans the next token of the input as a long.An invocation of this method of the form nextLong() behaves in exactly the same way as the invocation nextLong(radix), where radix is the default radix of this scanner.

What is nextDouble in Java?

nextDouble() method scans the next token of the input as a double. This method will throw InputMismatchException if the next token cannot be translated into a valid double value. If the translation is successful, the scanner advances past the input that matched.

What is Java Util InputMismatchException?

java.util.InputMismatchException. Thrown by a Scanner to indicate that the token retrieved does not match the pattern for the expected type, or that the token is out of range for the expected type.

How do you use nextInt?

Example 3

  1. import java.util.*;
  2. public class ScannerNextIntExample3 {
  3. public static void main(String[] args) {
  4. Scanner scan = new Scanner(;
  5. System.out.print(“Number: “);
  6. int number = scan.nextInt();
  7. System.out.print(“String: “);
  8. String str =;

What is double parseDouble?

Double parseDouble() method in Java with examples

The parseDouble() method of Java Double class is a built in method in Java that returns a new double initialized to the value represented by the specified String, as done by the valueOf method of class Double.

What is NaN in Java?

Simply put, NaN is a numeric data type value which stands for “not a number”. In this quick tutorial, we’ll explain the NaN value in Java and the various operations that can produce or involve this value.

What is parse in Java?

Parsing is to read the value of one object to convert it to another type. For example you may have a string with a value of “10”. Internally that string contains the Unicode characters ‘1’ and ‘0’ not the actual number 10. The method Integer. parseInt takes that string value and returns a real number.

What is doubleValue () in Java?

doubleValue() is an inbuilt method in java that returns the value of the specified number casted as a double data type. This may involve rounding or truncation. Syntax: public abstract double doubleValue()

What is a float vs double?

A float has 7 decimal digits of precision and occupies 32 bits . A double is a 64-bit IEEE 754 double-precision floating-point number. 1 bit for the sign, 11 bits for the exponent, and 52 bits for the value. A double has 15 decimal digits of precision and occupies a total of 64 bits .

What is float and double in Java?

Float and Double are used to represent Floating-point numbers. Float and double are the two data types Java allocates for dealing with floating-point numbers. Both data types are primitive by nature: meaning that their definitions are included as part of the language itself (or more specifically, the java.

What is float value in Java?

A float data type in Java stores a decimal value with 6-7 total digits of precision. So, for example, 12.12345 can be saved as a float, but 12.123456789 can’t be saved as a float. When representing a float data type in Java, we should append the letter f to the end of the data type; otherwise it will save as double.

What is Boolean in Java?

A Boolean expression is a Java expression that returns a Boolean value: true or false .

What is byte in Java?

byte: The byte data type is an 8-bit signed two’s complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters.