[JAVA] A little worrisome code collection-I want to give you a chance to write good code. 2 [C # refactoring sample]

A collection of codes that are a little worrisome

During the code review, there was a source that I was interested in, so I will list it. It's not a big deal, but it can't be helped.

  1. Null check
            int? inputValue = null;

            //NG I couldn't think of such an implementation method, so I thought it was a little amazing.
            if (string.IsNullOrWhiteSpace(inputValue.ToString()))
            {
            }

            //Use the OK property
            if (!inputValue.HasValue)
            {
            }

            // OK !Nullable.This is fine because it is equivalent to HasValue.
            if (inputValue == null)
            {
            }

2. Extract value from nullable type.

            int? inputValue = 1;

            int value;
            if (inputValue.HasValue)
            {
                //NG Let's stop the idea that anything should be a character string
                value = int.Parse(inputValue.ToString());
                //NG useless cast 1
                value = Convert.ToInt32((object)inputValue);
                //Use OK property
                value = inputValue.Value;
                //OK Looks like a useless cast, but inputValue.Value is called.
                value = (int)inputValue;

            }


  1. Cast
            object objectValue = 1;
            int castValue;
            if (objectValue != null)
            {
                //Casting as an NG string is wasteful
                castValue = int.Parse(objectValue.ToString());
                // OK .Use the conversion process provided by Net Framework
                castValue = Convert.ToInt32(objectValue);
                //OK normal cast
                castValue = (int)objectValue;
            }

Summary

Many people think that it should be a character string. Even if there is no problem with the operation, the reviewer can not help it.

Sample code (Java) 2017/3/24 Added

        /**Null check**/
        Integer inputValue = null;

        //No one would write this in NG java.
        //By the way, C#Int?Is a Nullable structure, so no Null check was needed before ToString.
        if (inputValue == null || inputValue.toString().length() == 0) {

        }

        //OK For Java, it is correct to compare with null.
        if (inputValue == null) {

        }
        /**Nullable type**/
        Integer inputValue = 1;

        int value;
        if (inputValue != null) {
            //NG Let's stop the idea that anything should be a character string
            value = Integer.parseInt(inputValue.toString());
            //NG useless cast
            value = (int) inputValue;
            // OK Integer.intValue is called.
            value = inputValue;
            // OK
            value = inputValue.intValue();
        }

        /**Object type**/
        Object objectValue = 1;
        int castValue;
        if (objectValue != null) {
            //NG If you know the original type, you don't need to convert it to a string.
            castValue = Integer.parseInt(objectValue.toString());
            //OK Cast to original mold
            castValue = (int) objectValue;
        }

Previous article (confusing conditional branching)

[Next article (flowing interface)] (http://qiita.com/csharpisthebest/items/403d40374acc70ef24e3)

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