Java Scanner hasNextLong() Method

The hasNextLong() is a Java Scanner class method which is used to check the next token in this scanner's input can be interpreted as a long value in the default radix or not. It returns true if it is interprated as a long value, otherwise returns false. There is two different types of Java hasNextLong() method which can be differentiated depending on its parameter. These are:

Java Scanner hasNextLong() Method
Java Scanner hasNextLong(int radix) Method

hasNextLong() Method:

This is a Java Scanner class method which is used to check the next token in this scanner's input can be interpreted as a long value in the default radix using the nextLong() method.

hasNextLong(int radix) Method:

This is an inbuilt method of Java Scanner class which is used to check the next token in this scanner's input can be interpreted as a long value in the specified radix using the nextLong() method.

Syntax

Following is the declaration of hasNextLong() method:

public boolean hasNextLong()
public boolean hasNextLong(int radix)

Parameter

DataType	Parameter	Description	Required/Optional
int	radix	It is used to interpret the token as a long value.	Required

Returns

The hasNextLong() method returns true if and only if this scanner's next token is a valid long value.

Exceptions

IllegalStateException- This method throws exception if the innvocation is done after the scanner has been closed.

IllegalArgumentException- It throws this exception if the specified radix is out of range.

Compatibility Version

Java 1.5 and above

Example 1

import java.util.*;
public class ScannerHasNextLongExample1 {  
	public static void main(String[] args) {
		String str = "Facebook.com ";
	      Long l = 1234567890987654321L;
	      str = str + l;
	      Scanner scanner = new Scanner(str);	      
	      //We use US locale in order to be able to identify long in a string
	      scanner.useLocale(Locale.US);
	      while (scanner.hasNext()) {
	         //Check if the scanner's next token is a long value
	         System.out.println("Is Long Value: "+scanner.hasNextLong());
	         System.out.println("Scan String: "+scanner.next());
	      }
	      scanner.close();
	}
}

Output:

Is Long Value: false
Scan String: Facebook.com
Is Long Value: true
Scan String: 1234567890987654321

Example 2

import java.util.*;
public class ScannerHasNextLongExample2 {  
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("Give me a bunch of numbers in a line (or 'exit')");
		while (!sc.hasNext("exit")) {
		    Scanner lineSc = new Scanner(sc.nextLine());
		    int sum = 0;
		    while (lineSc.hasNextLong()) {
		        sum += lineSc.nextLong();
		    }
		    System.out.println("Sum is " + sum);
		    lineSc.close();
		}
		sc.close();		
	}
}

Output:

Give me a bunch of numbers in a line (or 'exit')
3745327 43569 5468943
Sum is 9257839

Example 3

import java.util.*;
public class ScannerHasNextLongExample3 {  
	public static void main(String[] args) {
		//Create the scanner object
		Scanner scan = new Scanner(" long number is ACE ");
		//Iterate through scanner tokens
		while(scan.hasNext()){
			//Print long value
			if(scan.hasNextLong(16)){
				System.out.println("Found Long: "+scan.next());
			}
			else{
				scan.next();
			}
		}
		scan.close();	
	}
}

Output:

Found Long: ACE

Example 4

import java.util.*;
public class ScannerHasNextLongExample4 {  
	public static void main(String[] args) {
		String str = " 11 Java 11 + 11 = 22.0";
            Scanner scanner = new Scanner(str);
            while (scanner.hasNext()) {
            if (scanner.hasNextLong()) {
                System.out.println("Found :" + scanner.nextLong(598670));
            }
            // if a Long is not found, print "Not Found" and the token
            System.out.println("Not Found :" + scanner.next());
            }
            scanner.close();
	}
}

Output:

Exception in thread "main" java.lang.IllegalArgumentException: radix:598670
	at java.base/java.util.Scanner.setRadix(Scanner.java:1368)
	at java.base/java.util.Scanner.nextLong(Scanner.java:2370)
	at myPackage.ScannerHasNextLongExample4.main(ScannerHasNextLongExample4.java:10)

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