indexOf

 可以通過String的indexOf判斷是否包括某個字符。

@SpringBootTest
@Slf4j
class BaseApplicationTests {@Testvoid contextLoads() {log.info("01".indexOf(".")+"");log.info("0.1".indexOf(".")+"");log.info("100.0".indexOf(".")+"");}
}

 com.book.base.BaseApplicationTests : -1

 com.book.base.BaseApplicationTests : 1

 com.book.base.BaseApplicationTests : 3