如何使用Java中的Scanner类读取单个字符？
从Java1.5开始引入Scanner类。此类接受File，InputStream，Path和String对象，使用正则表达式逐个令牌读取所有原始数据类型和String（从给定的源）令牌。默认情况下，空格被视为定界符（将数据分成令牌）。
使用Scanner类读取字符
Scanner类提供nextXXX()（其中xxx是int，float，boolean等）方法，这些方法用于读取各种原始数据类型。但是它从来没有提供读取单个字符的方法。
但是，您仍然可以使用此类读取单个字符。
next()Scanner类的方法以String格式返回源的下一个标记。这会将单个字符（由定界符分隔）读取为字符串。
String str = sc.next();
toCharArray()String类的方法将当前String转换为字符数组。
char ch[] = str.toCharArray()
从数组中可以获取存储在第0个位置的字符。
char myChar = ch[0];
示例
以下示例使用Scanner类从用户读取单个字符。
import java.util.Scanner;
public class ContentsOfFile {
public static void main(String args[]) throws Exception {
//创建扫描仪对象
Scanner sc = new Scanner(System.in);
//创建一个StringBuffer对象
System.out.println("Enter your grade: (A, B, C, D)");
char grade = sc.next().toCharArray()[0];
if(grade == 'A'){
System.out.println("You are very good, you have been promoted");
}else if(grade=='B'){
System.out.println("You are good, you have been promoted");
}else if(grade=='C'){
System.out.println("You are average, you have been " + "promoted, you need to work hard");
}else if(grade=='D'){
System.out.println("You are not promoted, try again");
}else {
System.out.println("Improper input");
}
}
}输出结果
Enter your grade: (A, B, C, D) C You are average, you have been promoted, you need to work hard