How to read development documents in java

As a college student, when I was learning Java at school, I followed the textbook step by step. I found that everyone did well in the final exam. But if you really have to write a program yourself, everyone seems to know what to do. Because everyone usually encounters very few classes and interfaces, and will only use the few in the book. Few people will check the Java documentation, and more people will directly search Baidu for the usage of that class and interface. I used to do this, but after reading Thinking in Java, I developed the habit of checking Java documents. The advantage is that I can find out what I don’t know and it also makes me more familiar with the entire Java framework. , and more importantly, it’s like looking up a dictionary, giving me a sense of superiority and comfort.

Before we use the help documentation, we first determine what class or method we want to check?

Here is an example. Let’s check the Math class.

First open the help document (the help document is platform-specific, for example, you are using JavaSE , then you cannot use the JavaEE API to check the classes and methods in JavaSE. You need to understand this clearly. There is a difference between the two.)

First we type Math in the index box (note the case, There is a difference between upper and lower case here)

After we complete the input, the blue part below means that it has been selected and just press Enter.

At this time, various knowledge related to the class or method will appear, such as method summary

means that the method is static (you can pass the class name. method name to call directly), the return value of the method is of Double type, the method name is abs, and the method needs to pass in a Double type parameter. The function of the method is to return the absolute value of the Double value (when we use this method, we don’t need to delve into how this method is implemented, as long as we know how to use it)

When sometimes we still don’t understand this method When we don't understand it too well, we can click on the method name, so that we will see a more detailed explanation.

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