扫描器有 Java 中的 NextLine()方法,示例
原文:https://www . geesforgeks . org/scanner-hasnextline-method-in-Java-with-examples/
Java . util . scanner类的 hasNextLine() 方法,如果这个扫描仪的输入中还有一行,则返回 true。此方法在等待输入时可能会阻塞。扫描仪不会前进超过任何输入。
语法:
public boolean hasNextLine()
参数:函数不接受任何参数。
返回值:当且仅当该扫描仪有另一行输入时,该函数返回真
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
// 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();
}
}
输出:
gfg 2 geeks!
程序二:程序演示异常
// 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);
}
}
}
输出:
Exception is: java.lang.IllegalStateException: Scanner closed
参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/scanner . html # hasNextLine()
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