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();
}
} |
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);
}
}
} |
Exception: java.lang.IllegalStateException: Scanner closed
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNextBoolean()