Scanner hasNextBoolean() method in Java with Examples

Last Updated : 16 Oct, 2018

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

// 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

// 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()

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