El método nextInt(radix) de la clase java.util.Scanner escanea el siguiente token de la entrada como un Int. Si la traducción es exitosa, el escáner avanza más allá de la entrada que coincidió. Si no se pasa el parámetro radix, entonces se comporta de manera similar a nextInt(radix) donde se supone que la base es la base predeterminada.
Sintaxis:
public int nextInt()
Parámetros: la función acepta un parámetro radix que se utiliza para interpretar el token como un valor Int.
Valor devuelto: Esta función devuelve el Int escaneado desde la entrada.
Excepciones: la función lanza tres excepciones como se describe a continuación:
- InputMismatchException: si el siguiente token no coincide con la expresión regular Integer o está fuera de rango
- NoSuchElementException: se lanza si la entrada está agotada
- IllegalStateException: se lanza si este escáner está cerrado
Los siguientes programas ilustran la función anterior:
Programa 1:
// Java program to illustrate the
// nextInt() 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 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
while (scanner.hasNext()) {
// if the next is a Int,
// print found and the Int
if (scanner.hasNextInt()) {
System.out.println("Found Int value :"
+ scanner.nextInt());
}
// if no Int is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Int value :"
+ scanner.next());
}
}
scanner.close();
}
}
Producción:
Not found Int value :Gfg Found Int value :9 Not found Int value :+ Found Int value :6 Not found Int value := Not found Int value :12.0
Programa 2:
// Java program to illustrate the
// nextInt() 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 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
while (scanner.hasNext()) {
// if the next is a Int,
// print found and the Int
if (scanner.hasNextInt()) {
System.out.println("Found Int value :"
+ scanner.nextInt(12));
}
// if no Int is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Int value :"
+ scanner.next());
}
}
scanner.close();
}
}
Producción:
Not found Int value :Gfg Found Int value :9 Not found Int value :+ Found Int value :6 Not found Int value := Not found Int value :12.0
Programa 3: Para demostrar InputMismatchException
// Java program to illustrate the
// nextInt() method of Scanner class in Java
// InputMismatchException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
while (scanner.hasNext()) {
// if the next is a Int,
// print found and the Int
// since the value 60 is out of range
// it throws an exception
System.out.println("Next Int value :"
+ scanner.nextInt());
}
scanner.close();
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Producción:
Exception thrown: java.util.InputMismatchException
Programa 4: Para demostrar NoSuchElementException
// Java program to illustrate the
// nextInt() method of Scanner class in Java
// NoSuchElementException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
// Trying to get the next Int value
// more times than the scanner
// Hence it will throw exception
for (int i = 0; i < 5; i++) {
// if the next is a Int,
// print found and the Int
if (scanner.hasNextInt()) {
System.out.println("Found Int value :"
+ scanner.nextInt());
}
// if no Int is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Int value :"
+ scanner.next());
}
}
scanner.close();
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Producción:
Not found Int value :Gfg Exception thrown: java.util.NoSuchElementException
Programa 5: Para demostrar IllegalStateException
// Java program to illustrate the
// nextInt() method of Scanner class in Java
// IllegalStateException
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
String s = "Gfg 9 + 6 = 12.0";
// create a new scanner
// with the specified String Object
Scanner scanner = new Scanner(s);
// close the scanner
scanner.close();
System.out.println("Scanner Closed");
System.out.println("Trying to get "
+ "next Int value");
while (scanner.hasNext()) {
// if the next is a Int,
// print found and the Int
if (scanner.hasNextInt()) {
System.out.println("Found Int value :"
+ scanner.nextInt());
}
// if no Int is found,
// print "Not Found:" and the token
else {
System.out.println("Not found Int value :"
+ scanner.next());
}
}
}
catch (Exception e) {
System.out.println("Exception thrown: " + e);
}
}
}
Producción:
Scanner Closed Trying to get next Int value Exception thrown: java.lang.IllegalStateException: Scanner closed
Referencia: https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#nextInt(int)