Problems encountered in Java learning and later thinking

Put yourself in the process of learning Java problems encountered in the list, write their own various periods of the idea of the problem, until the final resolution, should be to persist in learning this thing has been promoted.

1. See the Java Foundation Chapter, there is a piece of code to write the private Point Center (P65), what is point, ah, this position should not be a data type?

• The reason why I do not understand is that the data types and operations mentioned above may be omitted at the time, it may be in the back of the said I have not seen. This problem does not affect the overall situation, you can first put--2015/07/15

Problems encountered in Java learning and later thinking