# Scanner

**作用**：获取用户的键盘输入，他是基于正则表达式的文本扫描器。可以从文件、输入流、字符串中解析出基本类型和字符串的值。

主要提供两个方法来扫描输入：

* `hasNextXxx()`:是否还有下一个输入项
* `nextXxx()`:获取下一个输入项。

默认情况下，Scanner以 空格、Tab、回车作为多个输入项之间的分隔符，我们也可以使用`useDelimiter("分割符")`来设置分隔符。

**阻塞**： Scanner读取操作（hasNext与next）有可能会被阻塞（当前执行顺序流暂停），从而等待信息输入。

**逐行读取，不受文输入型限制**：

```java
boolean  hasNextLine(); 是否还有下一行
String nextLine(); 返回下一行字符串
```

## 小问题

```java
package me.feathers.scannerdemo;
import java.util.Scanner;

public class ScannerDemo{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        System.out.print("请您输入体重：");
        int weight = sc.nextInt();
        System.out.println("你的体重为"+weight);
        //此处的nextLine()失效了,程序将不再进入到阻塞状态了.（因为前面有nextInt/nextDouble，如果没有则不会出现该问题）【小问题】
        System.out.print("请您输入信息：");
        String meassage = sc.nextLine();
        System.out.println("你输入的内容为"+meassage);
    }
}
```


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