beidae的专栏

Java is a first-class object-oriented language. With the exception of primitive data types, everything in Java is an object. Even an array is an Object. Every class creates instances that are objects.

优先返回空集合而非null 如果程序要返回一个不包含任何值的集合，确保返回的是空集合而不是null。这能节省大量的”if else”检查。 public class getLocationName { return (null==cityName ? "": cityName); } 谨慎操作字符串 如果两个字符串在for循环中使用+操作符进行拼接，那么每次循环都会产生