"Learn no Java, no sorrow" of the five-dedicated to those who love computer programming

Program you netizens, this is "learn not to Java, will not be sad" of the five, this is not a pan Java master, the niche one and three, three and again in the Java Lian League. COM Free forum on the issue of absurd, I do not know whether it interfered with everyone? Anyway, the lights open every night, gossip said endless, without receiving the Post manager's serious warning, this long paste will continue to serial.

In order to 100% respect netizens, all these posts are I personally a word carefully produced, between the lines do not appear any links about other URLs, there is no commercial flavor, please rest assured to read.

I self-study Java more than two years, the first year found himself familiar with Java, the second year that Java has changed, a lot of places have not touched her, and now worse, more and more wood, is really "learning will not Java, not the sadness." sign~~ (I sigh in the long time!) ）
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Talk less, and come to the other.
With some basic concepts about classes and objects, let's take a look at the class library.

I do not know whether we have been in the factory, in Shenzhen, such as plastic products factory, hardware products factory can be many. In these factories, the production of things there is a life and death process-die manufacturing. After the mold completes, becomes the other product manufacture The example, should say "trough" more precisely. It is more popular to create a mold than to create a Java class. Perhaps, the former made the mold is hard, touch, give people the feeling of sureness, and the latter made Java Mold (Classes) is soft, give people not really feel. The so-called layman to see lively, insiders look at the doorway, those who make plastic, metal mold mold Workers Of course do not understand our Java-made software mold. However, the hard die or the soft mold, they are mostly the same in management. The person who will manage the Java mold will certainly manage the mold, in turn, it is not tenable, this is worth our Java family pride.

The more production and the longer the product is, the more molds there are. Many products are similar in appearance, you do not see the Nokia 3210 and 8250 models, in addition to the latter small, the body is basically the same, so most of the product of the high probability of reuse. For the next product development can quickly find this good mold, the mold to separate storage and sorting by name is a good way. Well, this is the Nokia 3210 series of mold cabinets, put the mold of this series, there are some mold specifications, technical information. Over there is the Nokia 8250 series of mold cabinets, storage of 8250 series of molds and specifications and technical information ... All of these tooling cabinets are stored in a house and call it a mold warehouse. This mold warehouse for the factory, the use of your tile is not big?

All Java molds, that is, all Java classes, are managed in exactly the same way as above. The longer you use Java to develop software, the more classes you write, for the next time you can borrow this writing class, you have to be like the above, to the Java class classification (please forgive me in the same sentence with two different meanings of a word), this class is used to make buttons, labels, text boxes and so on, The class is for the purpose of developing database applications, and the other is specially tuned color ... Each category to help him get a name, what name is good? In Java, it is called swing (called AWT as a child), SQL, color ... usually we don't say that. swing classes, SQL categories, color categories ..., but swing packages, SQL packages, color packages ... All these packages are stored in one place (i.e. a folder), so this is a gold mine.

The folder that contains all the Java packages is the common Java class Library, now you should understand that the class library inside the package, large packet packets, the package is placed in the class, big class small class, what is in the class? That's what I'm talking about, methods, attributes, and so on. Of course, sometimes, in the bag can also put something else, such as interface, exception, error, these things you do not know, I will be back to tell you the post.

A very important concept, in the mold library, some mold only similar products can be borrowed, some mold all products can be borrowed, and some simply can not borrow. The class in the Java package is the same, with all the classes in the package available, it is called the public class; There are classes within this package that can be used, called protect classes, and some classes are Shing, and no other class is allowed to hit it, which is called selfish (private) and, more absolutely, Most of the class will be born class, and some classes are impotent, not born, this is called what class? Java inside called sexual incompetence class, Oh, no no no, called the termination category (final), there seems to be several kinds, but I do not know how to address, ask Sun company!

In Java inside such classification have what effect, use can be big, this is something, this post does not mention.

Originally intended to talk about the inheritance concept of class and the concise use of JDK, because time is limited, this paste does not speak, please see the post bar!


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This post we talked about the concept of class library, what is called the package, why should all the classes into different kinds of packages, at the same time involving the public class, Protcet class, Pvivate class, final class of some explanations, these are very important concepts, you understand?

Until now, I have not given an example of a program to illustrate the problem, as the post development, the example will be more and more, and to explain the JDBC, solect, java beans, Enterprise java beans, Selvlet, applets ... And so on, there is no example to explain simply can't speak.

Please 200% rest assured that my mouth never out of people do not understand words, I once let a 64-year-old farmers in Jiangxi farming understand the concept of dynamic call VC.

At school, I run the computer Freedom Forum for nearly 3 years. In the classroom, the teacher told DOS no one listen, outside the classroom, I speak of DOS classroom crowded people.

My knowledge is very poor, know things too little, but I can understand what I have to let everyone understand. The way I spoke once surprised many small business owners, even our school's librarian, which is why I was able to get a software development business when I was at school.

Ah ah, also said the gossip, I'm sorry everyone, this posted to this end, the fun in the back, please see under the "Learn not to Java, not the sad" of the six-dedicated to those who love computer programming people.