Java 中 Scanner hasNextInt()方法，带示例
原文:https://www . geesforgeks . org/scanner-hasnextint-method-in-Java-with-examples/
如果这个扫描器的输入中的下一个标记可以被假定为给定基数的 Int 值，那么Java . util . scanner类的 hasNextInt() 方法返回 true。扫描仪不会前进超过任何输入。如果没有基数作为参数传递，函数会将基数解释为默认基数，并相应地运行。
语法:
public boolean hasNextInt(int radix)
or
public boolean hasNextInt()
参数:该函数接受单个参数基数，该基数不是强制的。它指定用于将令牌解释为 Int 值的基数。
返回值:当且仅当此扫描器的下一个令牌是默认基数中的有效 Int 值时，此函数返回 true。
异常:如果扫描仪关闭，该功能会抛出非法状态异常。
以下程序说明了上述功能:
程序 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();
}
}
输出:
false -> gfg
true -> 2
false -> geeks!
程序二:
// 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();
}
}
输出:
false -> gfg
true -> 2
false -> geeks!
程序 3: 程序演示异常
// 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);
}
}
}
输出:
Exception: java.lang.IllegalStateException: Scanner closed
参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/scanner . html # hasNextInt()
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