Java Scanner hasNextByte()方法及示例

java.util.Scanner 类的 hasNextByte() 方法，如果该扫描器输入的下一个标记可以被认为是给定的字节数的Byte值，则返回true。扫描器不会超过任何输入。如果没有将radix作为参数传递，该函数将radix解释为默认radix，并发挥相应的作用。

语法

public boolean hasNextByte(int radix)            orpublic boolean hasNextByte()

参数： 该函数接受一个参数radix，这不是一个强制性参数。它指定了用于将令牌解释为字节值的弧度。
返回值： 如果且仅当该扫描器的下一个令牌是默认弧度的有效字节值时，该函数返回真。
异常 ：如果该扫描器被关闭，该函数会抛出IllegalStateException。以下程序说明了上述函数：

程序1 :

// Java program to illustrate the// hasNextByte() 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 Bytes in a string        scanner.useLocale(Locale.US);         // iterate till end        while (scanner.hasNext()) {             // check if the scanner's            // next token is a Byte with a radix 3            System.out.print("" + scanner.hasNextByte(3));             // print what is scanned            System.out.print(" -> " + scanner.next() + "\n");        }         // close the scanner        scanner.close();    }}

输出

false -> gfgtrue -> 2false -> geeks!

程序2

// Java program to illustrate the// hasNextByte() 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 Bytes in a string        scanner.useLocale(Locale.US);         // iterate till end        while (scanner.hasNext()) {             // check if the scanner's            // next token is a Byte with the default radix            System.out.print("" + scanner.hasNextByte());             // print what is scanned            System.out.print(" -> " + scanner.next() + "\n");        }         // close the scanner        scanner.close();    }}

输出

false -> gfgtrue -> 2false -> geeks!

计划3： 展示例外情况的计划

// Java program to illustrate the// hasNextByte() 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 Bytes in a string            scanner.useLocale(Locale.US);             scanner.close();             // iterate till end            while (scanner.hasNext()) {                 // check if the scanner's                // next token is a Byte with the default radix                System.out.print("" + scanner.hasNextByte());                 // 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

**参考资料: ** https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNextByte()