第七色在线视频,2021少妇久久久久久久久久,亚洲欧洲精品成人久久av18,亚洲国产精品特色大片观看完整版,孙宇晨将参加特朗普的晚宴

public class StringMethod5 { public static void main(String[] args) { String str = "HELLO world"; String s = str.toLowerCase(); System.out.println("字符串str為轉(zhuǎn)換為小寫后為：" + s); String s1 = s.toUpperCase(); System.out.println("字符串s為轉(zhuǎn)換為大寫后為：" + s1); } }