Java 简明教程
Java Scanner Class
Introduction
Java Scanner 类是一个简单的文本扫描器，它可以使用正则表达式解析基本类型和字符串。以下是有关 Scanner 的要点 -
The Java Scanner class is a simple text scanner which can parse primitive types and strings using regular expressions.Following are the important points about Scanner −
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A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace.
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A scanning operation may block waiting for input.
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A Scanner is not safe for multithreaded use without external synchronization.
Class declaration
以下是 java.util.Scanner 类的声明 -
Following is the declaration for java.util.Scanner class −
public final class Scanner
extends Object
implements Iterator<String>Methods inherited
此类从以下类中继承方法：
This class inherits methods from the following classes −
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java.util.Object
Reading a Line from Console using Scanner Class Example
下面的示例展示了如何使用 Java Scanner nextLine() 从控制台读取一行，并使用 close() 方法关闭扫描器。我们使用给定的字符串创建一个扫描器对象。然后我们使用 nextLine() 方法打印字符串，然后使用 close() 方法关闭扫描器。
The following example shows the usage of Java Scanner nextLine() to read a line from Console and close() method to close the scanner. We’ve created a scanner object using a given string. Then we printed the string using nextLine() method and then scanner is closed using close() method.
package com.tutorialspoint;
import java.util.Scanner;
public class ScannerDemo {
public static void main(String[] args) {
String s = "Hello World! 3 + 3.0 = 6";
// create a new scanner with the specified String Object
Scanner scanner = new Scanner(s);
// print the next line of the string
System.out.println(scanner.nextLine());
// close the scanner
System.out.println("Closing Scanner...");
scanner.close();
System.out.println("Scanner Closed.");
}
}