Java 中 Scanner nextInt()方法示例
原文:https://www . geesforgeks . org/scanner-nextint-method-in-Java-with-examples/
Java . util . scanner类的 nextInt(基数)方法将输入的下一个标记作为 Int 进行扫描。如果翻译成功，扫描仪将通过匹配的输入。如果参数基数没有被传递，那么它的行为类似于 nextInt(基数)，其中基数被假定为默认基数。
语法:
public int nextInt()
参数:该函数接受一个参数基数，该参数用于将令牌解释为 Int 值。
返回值:此功能从输入返回 Int 扫描的。
异常:函数抛出如下三个异常:
- [T0】 inputismatexception: 【T1] If the next tag does not match the Integer regular expression or is out of range.
- [T0】 NoSuchElementException: 【T1] Thrown if the input is exhausted.
- [T0】 illegalstatexception: 【T1] Thrown if this scanner is closed.
以下程序说明了上述功能:
程序 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();
}
}
输出:
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
程序二:
// 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();
}
}
输出:
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
程序 3: 演示输入 ismatcheexception
// 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);
}
}
}
输出:
Exception thrown: java.util.InputMismatchException
程序 4: 演示 nosucheelementexception
// 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);
}
}
}
输出:
Not found Int value :Gfg
Exception thrown: java.util.NoSuchElementException
程序 5: 演示非法状态异常
// 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);
}
}
}
输出:
Scanner Closed
Trying to get next Int value
Exception thrown: java.lang.IllegalStateException: Scanner closed
参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/scanner . html # nextInt(int)
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