Chapter2.A Trip to Objectville.There will be objects.

What's the difference between a class and an object?

• A class is not an object.(but it's used to construct them).

• A class is a blueprint for an object.

The two uses of main:

• to test your real class

• to launch/start your Java application

类与对象的区别

• 类不是对象(但类能构造对象)

• 类是对象的蓝图

main的两个使用方式

• 测试你写好的类

• 运行你的Java程序