Code neatness -- function

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Function is probably one of the most important things we programmers face every day , But have you ever thought about , How to write a function well ？

One 、 Short

seeing the name of a thing one thinks of its function , Every function we write , It should be possible not to be too long , Don't write code into a function , Keep the function as short as possible ;

Two 、 Do one thing

A function requires a function to be completed , It is usually done in several steps , For example, write a function , The function is to put the elephant in the refrigerator ,

So this function needs three steps

1, Open the refrigerator ;

2, Put the elephant in ,

3, Close the refrigerator

Each of these three steps is one thing , Abstract into code , Each step should be encapsulated in a function , Three functions are needed to complete a function , Not a function ;

public class Client {    public static void main(String[] args) throws Exception{        ElephantToRefrigerator();    }    public static void ElephantToRefrigerator(){        openRefrigerator();        putElephant();        closeRefrigerator();    }    public static void openRefrigerator(){        System.out.println(" Open the refrigerator ");    }    public static void putElephant(){        System.out.println(" Put in the elephant ");    }    public static void closeRefrigerator(){        System.out.println(" Open the refrigerator ");    }}

Like the code above , Is to satisfy that the function only does one thing , If you write every operation in a function , That's what it's like

public class Client {    public static void main(String[] args) throws Exception{        ElephantToRefrigerator();    }    public static void ElephantToRefrigerator(){        System.out.println(" Open the refrigerator ");        System.out.println(" Put in the elephant ");        System.out.println(" Open the refrigerator ");    }   }

Some of them may say , Isn't that the same , There is one more line of code above

Yes , This is a simple case , In actual development , Often '' Put the elephant in the fridge '', Each step has dozens of lines of code , If you don't use function encapsulation , It will greatly affect the code reading ！

3、 ... and 、 Hierarchical abstraction of functions

A function , Sometimes, I will call multiple other functions to realize the functions , But in the process of calling other functions , We need to pay attention to , What level is the called function ,

For example , I have a function , After the user logs in , send data , And then quit , The code is as follows

 public static void doSomeThing(){        // Sign in         login();        // send data         sentMessage();        // sign out         logout();    }

The above code is the main flow of the function , Next you need to add details , For example, when sending data , You need to send the login time at the same time , But where to add details ？

public static void doSomeThing(){        // Sign in         login();        String time = TimeUitl.getTime();        // send data         sentMessage(String time);        // sign out         logout();    }

This is the wrong way to modify , Details like getting time , It should not be placed in the top-level function module , It should be placed in setMessage() Get it by yourself in the method

Four 、 Reduce function parameters

The function should have as few arguments as possible , Functions with more than three arguments are not recommended , If three or more parameters are required , It is recommended to use objects to encapsulate , Or use the creator mode to simplify the parameters

  5、 ... and 、 No side effect

In a function that mainly does query , Do not make other changes in this function , This is likely to cause unexpected consequences when called elsewhere

6、 ... and 、 Functions should be reused

Don't write the same function repeatedly , Functions should be reused many times

7、 ... and 、 Exception handling should be placed separately in the function

Not recommended in try It writes a lot of code , You can try to put the statements that may throw exceptions , Encapsulate it in a function , as follows

public class Test01 {    public static void main(String[] args) {        try {            fun();        } catch (Exception e) {            e.printStackTrace();        }    }    private static void fun() throws Exception{        System.out.println(" step 1");        System.out.println(" step 1");        System.out.println(" step 1");    }    private static void exceptionDeal(){        System.out.println(" Handling exceptions ");    }}

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