Scanner 在 Java 中有 NextDouble()方法，示例
原文:https://www . geesforgeks . org/scanner-hasnextdouble-method-in-Java-with-examples/
如果这个扫描器的输入中的下一个标记可以用 NextDouble()方法解释为 Double，那么这个类的 hasNextDouble() 方法返回 true。扫描仪不会前进超过任何输入。
语法:
public Double hasNextDouble()
参数:函数不接受任何参数。
返回值:当且仅当该扫描器的下一个令牌是有效的 Double 时，该函数返回 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
// hasNextDouble() 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 Doubles in a string
scanner.useLocale(Locale.US);
// iterate till end
while (scanner.hasNext()) {
// check if the scanner's
// next token is a Double with the default radix
System.out.print("" + scanner.hasNextDouble());
// 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:程序演示异常
// Java program to illustrate the
// hasNextDouble() 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 Doubles in a string
scanner.useLocale(Locale.US);
scanner.close();
// iterate till end
while (scanner.hasNext()) {
// check if the scanner's
// next token is a Double with the default radix
System.out.print("" + scanner.hasNextDouble());
// 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 # hasNextDouble()
版权属于：月萌API www.moonapi.com，转载请注明出处
