The hasNextBoolean() method of java.util.Scanner class returns true if the next token in this scanner’s input can be interpreted as a Boolean using the nextBoolean() method. The scanner does not advance past any input.
Syntax:
public boolean hasNextBoolean()
Parameters: The function does not accepts any parameter.
Return Value: This function returns true if and only if this scanner’s next token is a valid Boolean.
Exceptions: The function throws IllegalStateException if this scanner is closed.
Below programs illustrate the above function:
Program 1:
// Java program to illustrate the// hasNextBoolean() method of Scanner class in Java// without parameter  import java.util.*;  public class GFG1 {    public static void main(String[] argv)        throws Exception    {          String s = "gfg true geeks!";          // new scanner with the        // specified String Object        Scanner scanner = new Scanner(s);          // use US locale to interpret Booleans in a string        scanner.useLocale(Locale.US);          // iterate till end        while (scanner.hasNext()) {              // check if the scanner's            // next token is a Boolean with the default radix            System.out.print("" + scanner.hasNextBoolean());              // print what is scanned            System.out.print(" -> " + scanner.next() + "\n");        }          // close the scanner        scanner.close();    }} |
Output:
false -> gfg true -> true false -> geeks!
Program 2: Program to demonstrate exception
// Java program to illustrate the// hasNextBoolean() method of Scanner class in Java// Exception case  import java.util.*;  public class GFG1 {    public static void main(String[] argv)        throws Exception    {          try {            String s = "gfg 2 geeks!";              // new scanner with the            // specified String Object            Scanner scanner = new Scanner(s);              // use US locale to interpret Booleans in a string            scanner.useLocale(Locale.US);              scanner.close();              // iterate till end            while (scanner.hasNext()) {                  // check if the scanner's                // next token is a Boolean with the default radix                System.out.print("" + scanner.hasNextBoolean());                  // print what is scanned                System.out.print(" -> " + scanner.next() + "\n");            }              // close the scanner            scanner.close();        }        catch (IllegalStateException e) {            System.out.println("Exception: " + e);        }    }} |
Output:
Exception: java.lang.IllegalStateException: Scanner closed
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNextBoolean()
