Java Scanner hasNextBigInteger()用法及代碼示例

如果可以假定此掃描器輸入中的下一個標記為給定基數的BigInteger值，則java.util.Scanner類的hasNextBigInteger()方法將返回true。掃描儀不會越過任何輸入。如果沒有將基數作為參數傳遞，則函數將基數插入為默認基數，並相應地運行。

用法:

public boolean hasNextBigInteger(int radix)
            or
public boolean hasNextBigInteger()

參數：該函數接受一個非必需的參數基數。它指定用於將標記解釋為BigInteger值的基數。

返回值：當且僅當此掃描器的下一個令牌是默認基數中的有效BigInteger值時，此函數才返回true。

異常：如果此掃描儀關閉，則此函數將引發IllegalStateException。

以下示例程序旨在說明上述函數：

程序1:

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

輸出：

false -> gfg
true -> 2
false -> geeks!

程序2:

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

輸出：

false -> gfg
true -> 2
false -> geeks!

程序3:演示異常的程序

// Java program to illustrate the 
// hasNextBigInteger() 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 BigIntegers in a string 
            scanner.useLocale(Locale.US); 
  
            scanner.close(); 
  
            // iterate till end 
            while (scanner.hasNext()) { 
  
                // check if the scanner's 
                // next token is a BigInteger with the default radix 
                System.out.print("" + scanner.hasNextBigInteger()); 
  
                // print what is scanned 
                System.out.print(" -> " + scanner.next() + "\n"); 
            } 
  
            // close the scanner 
            scanner.close(); 
        } 
        catch (IllegalStateException e) { 
            System.out.println("Exception:" + e); 
        } 
    } 
}

輸出：

Exception:java.lang.IllegalStateException:Scanner closed

參考： https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#hasNextBigInteger()

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