System.in.read() && java.io.IOException

import java.io.IOException;

public class Test
{
    public static void main (String[] args)
    throws IOException
    {
        char a = (char) System.in.read(); //默认接受int，如果需要输出char,需要type cast
        int b = System.in.read(); //这里就不需要type cast了
        System.out.println("a = " + a);
        System.out.println("b = " + b);
    }
}

运行程序, 仅输入a, 然后回车，会得到
a = a;
b = 10; // 对应的是line feed的ASCII值