To become a programmer from a Java shop

1. To become a programmer from a Java shop

I'm basically a Java shop, but I decided to write a program on for a certain project. I thought was Bimyo, but I thought that it wasn't much different from Java, so I wrote an article about the difference as a memorandum. It is a so-called poem. If you have the opportunity to become a programmer from a Java shop, I hope it helps a little.

2. Differences between Java and

I would like to explain the difference from from the perspective of a Java shop. If you want to see the code from the beginning, please refer to [3. Sample](# 3-Sample).

2.1. also has a Class is an object-oriented language because it is part of the .Net Framework. People from VB6 seem to use it less often, but you can also define Class in When using it, new is used to create an object.

2.2. Naming conventions (methods, properties) are LowerCamelCase for Java and UpperCamelCase for

Both are based on CamelCase, but is also based on ʻUpperCamelCasefor methods and properties. From a Java shop, it's hard to tell the difference fromClass` at first glance, but that's what it is.

2.3. Java package is Namespace also has the concept of packaging. Enclose it in a block called Namespace. Java packages are tied to the directory structure, but's Namespace has nothing to do with the directory structure.

Also, if you use names with Class name and Namespace name, an error will occur in the build. In Java, the package is lowercase and the Class name is ʻUpperCamelCase`, so it can be judged, but I think that cannot be judged by the same naming convention. (maybe)

2.4. Java imports are Imports

Java's ʻimport specifies Class (excluding static imports), while's ʻImports specifies Namespace. It feels strange because Java does not specify a package for ʻimport. (. * Can be seen visually) Even in, when setting an alias, specify the end Class`, but in this case, the description is different, so you can see it visually.

2.5. Methods with a return value of void are Sub

In, the method of defining a method differs depending on the presence or absence of a return value. If there is no return value, that is, if it is void in Java, it is defined as Sub (subroutine).

2.6. The method for which the return value exists is Function

If there is a return value, defines it as a Function. If you want to change the presence or absence of the return value, is a bit of a mess.

2.7. Java static is Shared

When implementing a little utility function in Java, I think that it is usually a static method. In this is not static but Shared.

2.8. Java annotations are attributes also has a function equivalent to Java annotation. That is the attribute. Input checking attributes similar to Java's Bean Validation are provided as a basic function. For more information, see Microsoft Page.

2.9. also has generics (, type parameters)

I think that generics (, type parameters) are a common feature in Java these days. Of course, also has this feature as a language specification.

3. Sample

As a sample, I would like to realize the same thing as input checking using Java Bean Validation with Since I set it to Sub with no return value, the above-mentioned Function does not appear, but I tried to pack everything else. As with Bean Validation, input checking using attributes is simple, easy and convenient.


Imports System.ComponentModel.DataAnnotations

Namespace Com.Example.Demo
    Public Class User
        <Display(Name:="User ID")>  _
        <Required(ErrorMessage := "{0}Is a required entry.")> _
        Public Property UserId As String
        <Display(Name:="name")> _
        <Required(ErrorMessage := "{0}Is a required entry.")> _
        Public Property Name As String

        <Display(Name:="age")> _
        <StringLength(3, MinimumLength :=1 ,ErrorMessage := "{0}Is{2}More than a digit{1}Please enter within digits.")> _
        Public Property Age As String
    End Class
End Namespace


Imports System.ComponentModel.DataAnnotations
Imports System.Collections.Generic

Namespace Com.Example.Demo
    Public Class ValidateService
        Public Shared Sub Validate(Of T)(target As T)
            Dim validationResults As New List(Of ValidationResult)
            Dim vc As New ValidationContext(target, Nothing, Nothing)
            Dim isValid As Boolean = Validator.TryValidateObject(target, vc, validationResults, true)
            If validationResults.Count > 0 Then
                Console.WriteLine("Input value check[NG]")
                For Each err As ValidationResult IN validationResults
                    Console.WriteLine("{0} : {1}", err.MemberNames(0), err.ErrorMessage)
                Console.WriteLine("Input value check[OK]")
            End If
        End Sub
    End Class
End Namespace


Namespace Com.Example.Demo
    Public Module App
        Public Sub Main()
            Console.WriteLine("// ------- Validate 1 -------")
            'Input data
            Dim input01 As new User()
            'Input value check
            ValidateService.Validate(Of User)(input01)

            Console.WriteLine("// ------- Validate 2 -------")
            'Input data
            Dim input02 As new User()
            input02.UserId = "123456"
            input02.Name = "TARO TOYOSU"
            input02.Age = "1234"
            'Input value check
            ValidateService.Validate(Of User)(input02)

            Console.WriteLine("// ------- Validate 3 -------")
            'Input data
            Dim input03 As new User()
            input03.UserId = "123456"
            input03.Name = "TARO TOYOSU"
            input03.Age = "123"
            'Input value check
            ValidateService.Validate(Of User)(input03)

        End Sub
    End Module
End Namespace

Java compiles with javac, while compiles with vbc. Of course, just as Java has build tools like Maven and Ant, also has a build tool called MsBuild.


@echo off
set DOTNET_HOME=C:\Windows\Microsoft.NET\Framework64\v4.0.30319
set path=%path%;%DOTNET_HOME%
vbc /out:DemoApp.exe /r:System.ComponentModel.DataAnnotations.dll ^
/r:System.ServiceModel.Web.dll ^
App.vb User.vb ValidateService.vb

Modify the environment variable of DOTNET_HOME according to your own environment. If you store all the files in the same directory and execute build.bat, DemoApp.exe will be created.

Execution result

Microsoft (R) Visual Basic Compiler version 14.7.2558
for Visual Basic 2012
Copyright (c) Microsoft Corporation.  All rights reserved.

This compiler is provided as part of the Microsoft (R) .NET Framework, but only supports language versions up to Visual Basic 2012, which is no longer the lates
t version. For compilers that support newer versions of the Visual Basic programming language, see

// ------- Validate 1 -------
Input value check[NG]
UserId :User ID is required.
Name :The name is required.
// ------- Validate 2 -------
Input value check[NG]
Age :Please enter the age between 1 and 3 digits.
// ------- Validate 3 -------
Input value check[OK]


4. Finally

This time, I explained the difference (part) between Java and from the perspective of a Java shop. Since is part of the .Net Framework, an object-oriented language, you'll find that it's not much different from Java, the same object-oriented language. C # is even closer to Java, but (unfortunately there are still many projects that love VB ** so I hope it helps you when you decide to use

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