Explain Java scanner class and constructor with example?

Java has several classes in its components. In this article, I would like to mention java scanner class. The java scanner class consists of following

• Java scanner class 
• Class constructors
• Java  scanner class modifier

So first let us see in brief about Java scanner class.

Java scanner class:

Java Scanner Class is a class in java.util package that uses primitive types such as int, double, etc., and strings to get data. Reading input in a Java program is the simplest way.

Typically we transfer the predefined object System.in, which represents the default input stream, to build a Scanner class object. If we want to read input from a file, we can transfer an object in class File.

The feature to use is nextXYZ()for reading numerical values of a given data form XYZ. For example, we can use nextShort()To read strings, we use nextLine()to read a short type value.

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We use next charAt(0), to read a single character. If you want to return to next character in the string use next() function, the next token or word in the input string and to return first character we use charat()The Java scanner class has the following components

• Class constructors
• modifiers

Class constructor in java:

These are several class constructors in java scanner class.

1. Scanner(File source) 

Builds a new Scanner which produces scanned values from the specified file.

2.  Scanner(File source, String charsetName)

 Constructs a new Scanner which generates scanned values from the specified file.

3.  Scanner(InputStream source) 

Builds a new Scanner which produces scanned values from the specified input stream.

4.  Scanner(InputStream source, String charsetName) 

Constructs a new Scanner which produces scanned values from the specified input stream.

5.  Scanner(Readable source)

 Constructs a new Scanner which produces scanned values from the specified source.

6.  Scanner(String source) 

It Creates a new Scanner that produces scanned values from the given Java string.

7. Scanner(ReadableByteChannel source) 

It Creates a new Scanner that generates values scanned from the channel specified.

8.  Scanner(ReadableByteChannel source, String charsetName) 

Builds a new Scanner that produces values scanned from the channel in question.

9. Scanner(Path source) 

Builds a new Scanner which produces scanned values from the specified file.

10.  Scanner(Path source, String charsetName) 

Constructs a new Scanner which generates scanned values from the specified file.

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Java scanner class methods:

The following are java methods. I listed out the modifiers and the method of using it

Vacuum

 Method: close()

We use this scanner  to close.

Pattern 

Method: delimiter()

We use the pattern that the Scanner class actually uses to suit boundaries to get it.

 Stream

Method:  < MatchResult > findAll()

We use it to find a match string matching the specified pattern list.

 String 

Method: findInLine()

We use it to find the next occurrence of a pattern constructed from the specified string, ignoring boundaries.

 String find

Method: WithinHorizon()

We use it to detect the next occurrence of a pattern constructed from the specified string, ignoring boundaries.

 Boolean 

Method:  hasNext()

If this scanner has a different token in its input, it will return valid.

Boolean 

Method: NextBigDecimal()

We use it to test whether or not the next token in the input of that scanner can be interpreted as BigDecimal using the nextBigDecimal()process.

Boolean 

Method: NextBigInteger()

It Checks whether or not the next token in the input of this scanner can be interpreted as a BigDecimal using the nextBigDecimal()process.

 Boolean 

Method: NextBoolean()

We use it to test whether or not the next token in the input of the scanner can be interpreted as Boolean using the nextBoolean()process.

 Boolean 

Method: NextByte()

We use it to check whether or not the next token in the input of this scanner can be interpreted as a Byte using the nextBigDecimal()process.

Boolean

Method:  NextDouble()

We use it to test whether or not the next token in the input of that scanner can be interpreted as BigDecimal using the nextByte()method.

 Boolean 

Method: NextFloat()

It Checks whether or not the next token in the input of this scanner can be interpreted as a Float using the nextFloat()form.

Boolean 

Method: NextInt()

We use it to evaluate whether or not the next token in the input of this scanner can be interpreted as an int using the nextInt()process.

 Boolean 

Method: NextLine()

We use it to verify if the input of this scanner has a different line or not.

 Boolean 

Method: NextLong()

We use it to test whether or not the next token in the input of the scanner can be interpreted as a Long using the nextLong()process.

 Boolean 

Method: NextShort()

We use it to test whether or not the next token in the input of the scanner can be interpreted as a Short using the nextShort()process.

IOException

 Method: ioException()

We use it to get the last thrown IOException readable by this Scanner.

Local locale()

Method: We use it to get a Scanner class Local.

 MatchResult 

Method: match()

The result of the last scanning operation performed by this scanner is used to get match.

String 

Method: next()

We use it to get the next complete token from the scanner you are using.

BigDecimal 

Method: nextBigDecimal()

It Scans the BigDecimal token next to the data.

BigInteger 

Method: nextBigInteger()

It Checks the next input token as a BigInteger.

 Boolean 

Method: nextBoolean()

It Scans the next input token into a boolean value, returning the value.

 Byte 

Method: nextByte()

It Checks the next input token as byte.

 Double 

Method: nextDouble()

It Scans the next input token as double.

 Float

Method:  nextFloat()

It Checks the next input token like a float.

int 

Method: nextInt()

It Scans the next Input token as an Int.

 String 

Method: nextLine()

The input string which was skipped from the Scanner object is used to get.

 Long 

Method: nextLong()

It Scans the next input token as long.

Short 

Method: nextShort()

It Scans the next input token as short.

 int 

Method: radix()

The default radix for use with the Scanner is used.

Void 

Method: remove()

We use it when this Iterator implementation does not support the remove operation.

 Reset()

We use Scanner to reset the Scanner currently in use.

 Scanner 

Method: skip()

It Skips input that fits the specified sequence, ignoring boundaries 

 Stream 

Method: < String > tokens()

We use it to get a delimiter-separated tokens stream from the Scanner object being used.

 String 

Method: toString()

It is for using the Scanner string representation.

 Use

Method: Delimiter()

Scanner is used to set the Scanner bonding pattern in use to the specified pattern.

Use

Method: Locale()

Scanner to set the locale object of this scanner to the specified locale.

 Scanner 

Method: useRadix()

We use The default Scanner radix for the specified radix.

Example for java scanner class:

Let us see a simple example program for java scanner class.

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();             
          }  
}  

By running this program in the compiler you get output of entered name.

Conclusion:

I hope you reach a conclusion about the Java Scanner class by reading this article. You can learn more about Java scanner class, constructor classes, modifiers through java certification course from industry experts.