Scanner hasNextInt() method in Java with Examples

02 Dec, 2021
The hasNextInt() method of java.util.Scanner class returns true if the next token in this scanner’s input can be assumed as a Int value of the given radix. The scanner does not advance past any input. In case no radix is passed as a parameter, the function interpretes the radix to be default radix and functions accordingly.
Syntax:
public boolean hasNextInt(int radix)
            or
public boolean hasNextInt()
Parameters: The function accepts a single parameter radix which is not a mandatory one. It specifies the radix used to interpret the token as a Int value.
Return Value: This function returns true if and only if this scanner’s next token is a valid Int value in the default radix.
Exceptions: The function throws IllegalStateException if this scanner is closed.
Below programs illustrate the above function:
Program 1:
// Java program to illustrate the// hasNextInt() method of Scanner class in Java// with parameter  import java.util.*;  public class GFG1 {    public static void main(String[] argv)        throws Exception    {          String s = "gfg 2 geeks!";          // new scanner with the        // specified String Object        Scanner scanner = new Scanner(s);          // use US locale to interpret Ints in a string        scanner.useLocale(Locale.US);          // iterate till end        while (scanner.hasNext()) {              // check if the scanner's            // next token is a Int with a radix 3            System.out.print("" + scanner.hasNextInt(3));              // print what is scanned            System.out.print(" -> " + scanner.next() + "\n");        }          // close the scanner        scanner.close();    }}
false -> gfg
true -> 2
false -> geeks!

Program 2:
// Java program to illustrate the// hasNextInt() 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 2 geeks!";          // new scanner with the        // specified String Object        Scanner scanner = new Scanner(s);          // use US locale to interpret Ints in a string        scanner.useLocale(Locale.US);          // iterate till end        while (scanner.hasNext()) {              // check if the scanner's            // next token is a Int with the default radix            System.out.print("" + scanner.hasNextInt());              // print what is scanned            System.out.print(" -> " + scanner.next() + "\n");        }          // close the scanner        scanner.close();    }}
false -> gfg
true -> 2
false -> geeks!

Program 3: Program to demonstrate exception
// Java program to illustrate the// hasNextInt() 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 Ints in a string            scanner.useLocale(Locale.US);              scanner.close();              // iterate till end            while (scanner.hasNext()) {                  // check if the scanner's                // next token is a Int with the default radix                System.out.print("" + scanner.hasNextInt());                  // 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#hasNextInt()
sinhaparty22
Java - util package
Java-Functions
Java-Scanner
Java
Java
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