Avoid over-streamlining temporary variables-refactoring

Avoid over-streamlining temporary variables-refactoring

 

During the refactoring process, a problem occurred in my code and an endless loop occurred!

An important means of refactoring is to remove the hateful temporary variables and change them to method calls. This is an idea that Martin Fowler emphasizes.

A major means and goal of refactoring is to extract methods.
The code of a large segment is divided into many micro functions. A major obstacle to function extraction is the appearance of variables everywhere, especially temporary variables that sometimes do not use much.

As a result, I took the temporary variable as a thorn in the eye, and tried every means to delete it. I used multiple methods to call these temporary variables instead.

 

However, a fatal endless loop occurs during indirect code execution!

 

Please refer to this method:

Public Boolean
Isnonerepeatinlist (list excelmodellist) throws exception {

/*

* Do not use more than one method. It is still required for appropriate temporary variables!

*
Note: Some methods are still factory methods. If you use them together, it will lead to the problem of creating an instance every time!

**/

Od1adsluserforecastmodelservice Service
= (Od1adsluserforecastmodelservice)
Getbean (systemconstantssdl. od1adsluserforecastmodel_service );

While (excelmodellist. iterator (). hasnext ()){

Od1adsluserforecastmodel
Tmpmodel = (od1adsluserforecastmodel) excelmodellist. iterator (). Next ();

List
Repeatmodellist = service. querybysectionnamesubstationnamenodenameforecastyear1forecastquarter1name (tmpmodel );

If (repeatmodellist. Size ()> 1 ){

// Delete this batch of records deletebybatchnum (string
Batchnum)

// Public void
Deletebybatchnum (datadeclarequerymodeladslforecast model) throws exception

Service. deletebybatchnum (tmpmodel );

Throw new telecomexception ("info. howdoiferror", "Sorry, the Excel file you uploaded contains the entered data. Please check your Excel file! ");

}

}

Return true;

}

 

In this method, I use the code excelmodellist. iterator (). hasnext () and excelmodellist. iterator (). Next.

Excelmodellist. iterator () actually creates an object.

The above two sentences lead to a new object every time, and then call its. hasnext (). In this way, even if list has only one object, it can always have. hasnext () = true!

 

This is the problem!

Therefore, the following conclusions can be drawn:

1,
Do not use multiple methods consecutively. Only one method can be called at a time. To avoid mistakes!

2,
Do not exclude the use of temporary variables. Temporary variables make the code easier to understand.
Although sometimes they provide redundant information, this is much better than the error implementation caused by insufficient information!

------- Do not miss it!

3,
In fact, the temporary variables we oppose are the temporary variables that oppose the multiple meanings of the word.

That is, we oppose a temporary variable being assigned multiple times in different statements-representing multiple semantics.

4. The solution is to ensure that the variable value is assigned once. Adding final to the variable can explicitly prevent the variable from being assigned multiple times!

 

Enclose the correct code:

Public Boolean isnonerepeatinlist (list
Excelmodellist) throws exception {

/*

* Do not use more than one method.
Appropriate temporary variables are required!

* Note: Some methods are still factory methods. If you use them together, it will lead to the problem of creating an instance every time!

**/

Od1adsluserforecastmodelservice service =
(Od1adsluserforecastmodelservice)
Getbean (systemconstantssdl. od1adsluserforecastmodel_service );

Iterator = excelmodellist. iterator ();

While (iterator. hasnext ()){

Od1adsluserforecastmodel
Tmpmodel = (od1adsluserforecastmodel) iterator. Next ();

List
Repeatmodellist = service. querybysectionnamesubstationnamenodenameforecastyear1forecastquarter1name (tmpmodel );

If (repeatmodellist. Size ()> 1 ){

// Delete this batch of records deletebybatchnum (string
Batchnum)

// Public void
Deletebybatchnum (datadeclarequerymodeladslforecast model) throws exception

Service. deletebybatchnum (tmpmodel );

Throw new
Telecomexception ("info. howdoiferror", "Sorry, the Excel file you uploaded contains the entered data. Please check your Excel file! ");

}

}

Return true;

}