练习1判断字符大小写

package yinshifuxi;

public class Demo2 {

    public static void main(String[] args) {
        char ch = 'a';
        if (Character.isUpperCase(ch)) {
            System.out.println("字符：" + ch + "是大写字符");
        } else {
            System.out.println("字符：" + ch + "是小写字符");
        }

    }

}

结果是 ：字符：a是小写字符