Java Scanner hasNextLine()用法及代碼示例

如果此掃描器的輸入中還有另一行，則java.util.Scanner類的hasNextLine()方法將返回true。等待輸入時，此方法可能會阻塞。掃描儀不會越過任何輸入。

用法:

public boolean hasNextLine()

參數：該函數不接受任何參數。

返回值：當且僅當此掃描儀具有另一行輸入時，此函數才返回true

異常注意：如果關閉此掃描器，則此函數將引發IllegalStateException。

以下示例程序旨在說明上述函數：

示例1:

// Java program to illustrate the 
// hasNextLine() 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 Lines in a string 
        scanner.useLocale(Locale.US); 
  
        // iterate till end 
        while (scanner.hasNextLine()) { 
  
            // print what is scanned 
            System.out.println(scanner.nextLine()); 
        } 
  
        // close the scanner 
        scanner.close(); 
    } 
}

輸出：

gfg 2 geeks!

示例2:演示異常的程序

// Java program to illustrate the 
// hasNextLine() method of Scanner class in Java 
// without parameter 
  
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 Lines in a string 
            scanner.useLocale(Locale.US); 
  
            scanner.close(); 
  
            // iterate till end 
            while (scanner.hasNextLine()) { 
  
                // print what is scanned 
                System.out.println(scanner.nextLine()); 
            } 
  
            // close the scanner 
            scanner.close(); 
        } 
        catch (IllegalStateException e) { 
            System.out.println("Exception is: " + e); 
        } 
    } 
}

輸出：

Exception is: java.lang.IllegalStateException: Scanner closed

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

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注：本文由純淨天空篩選整理自gopaldave大神的英文原創作品 Scanner hasNextLine() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。