【继续更新】把.net代码转换为java代码的注意事项_Java相关

【持续更新】把.net代码转换为java代码的注意事项

国内大多数大学的软件相关专业大多强制学生学习c和Java，但.net 的几个语言可以说是选学的。

由于visual studio在windows平台上使用相对方便，一些同学会在上大学的Java课之前自学.net开发技术。

这一类同学就需要一些代码转换技巧来帮助学习Java。

在这之前我吐槽一下TinyMCE编辑器，它不能正确染色一些vb.net的关键字，比如Async, NameOf, Aggregate 。c#的某些关键字也不能正确染色，如__arglist。

由于我这学期才开始上Java课，代码中出现的错误欢迎大家指正。

1. 枚举类型

Public Enum Direction    Right = 1    DownRight    Down    DownLeft    Left    UpLeft    Up    UpRightEnd Enum

        public enum Direction        {            Down = 1,            DownLeft,            Left,            UpLeft,            Up,            UpRight,            Right,            DownRight        }

转换成Java是这样的。感觉跟c++/cli和c++/cx的enum class差不多。

如果原先的枚举比较长，最好写个小程序转换一下。

public enum Direction {            Down(1),            DownLeft(2),            Left(3),            UpLeft(4),            Up(5),            UpRight(6),            Right(7),            DownRight(8)    private int __value;    private Direction(int value) {        this.__value = value;    }    @Override    public String toString() {        return String.valueOf(this.nCode);    }}

那个__value是我抄.net参考源码的，如果看不顺眼可以改名。

2.异常

Java的异常如果不是RuntimeException这一类的，就得用Throws 声明，否则像AccessViolationException这一类错误一样只能在UnhandledException（ErrorListener）那里处理。

转换代码的时候写一堆Throws比较麻烦，写了一层就忘了下面那一层有什么异常了。

这个比较好办，只要不是致命的异常，那自定义异常就都继承RuntimeException好了。自带的几个需要用Throws的异常用ErrorListener拦截。

class PointOutOfScreenException extends RuntimeException{    public PointOutOfScreenException(){        super("点出屏幕了...");    }}

3.标识符类型的推断

Dim a = New StringBuilder

var a = new StringBuilder();

转换成Java就用复制粘贴大法，把类名复制一下然后粘贴到开头

StringBuilder a = new StringBuilder();

4. c#不安全模式, vb和f#各种调运行库的独有运算符, 动态, async, await, linq, 无符号类型 .......

        Async Function LoadImages(device As CanvasDevice) As Task            forestTiles = Await SpriteSheet.LoadAsync(device, $"SpriteSheets/ForestTiles{NameOf(ImageID)}.png", New Vector2(64, 64), Vector2.Zero)            wizardWalk = Await SpriteSheet.LoadAsync(device, "SpriteSheets/WizardWalkRight.png", New Vector2(128, 192), New Vector2(64, 150))            wizardIdle = Await SpriteSheet.LoadAsync(device, "SpriteSheets/WizardIdleRight.png", New Vector2(128, 192), New Vector2(64, 150))        End Function

        async Task LoadImages(CanvasDevice device)        {            forestTiles = await SpriteSheet.LoadAsync(device, $"SpriteSheets/ForestTiles{nameof(ImageID)}.png", new Vector2(64, 64), Vector2.Zero);            wizardWalk = await SpriteSheet.LoadAsync(device, "SpriteSheets/WizardWalkRight.png", new Vector2(128, 192), new Vector2(64, 150));            wizardIdle = await SpriteSheet.LoadAsync(device, "SpriteSheets/WizardIdleRight.png", new Vector2(128, 192), new Vector2(64, 150));        }

    Public Function CalculateClipGeometry(resource As ICanvasResourceCreator, SourcePoint As Vector2, Geometies As CanvasGeometry(), ScreenSize As Size) As CanvasGeometry        Dim geos = Aggregate geo In Geometies                       Let Lines = Aggregate tes In geo.Tessellate                                   From ln In {New LineSegment(tes.Vertex1, tes.Vertex2), New LineSegment(tes.Vertex1, tes.Vertex3), New LineSegment(tes.Vertex3, tes.Vertex2)}                                   Select ln Distinct Into ToArray                       Select Rays = Aggregate tes In geo.Tessellate                           From light In {New LineSegment(SourcePoint, tes.Vertex1), New LineSegment(SourcePoint, tes.Vertex2), New LineSegment(SourcePoint, tes.Vertex3)}                               Where Not (Aggregate l In Lines Where light.RayToBoundary(ScreenSize).HasIntersection(l) Into Any)                           Select light                       Into ToArray                       Where Rays.Length >= 2 AndAlso Rays(0).Name Like "Ln*"                       Let Fir = Rays.First                       Select Arr = Aggregate ln In Rays Order By ln.Angle(Fir) Into ToArray                       Select CanvasGeometry.CreatePolygon(resource, {Arr.First.Point2, Arr.First.RayToBoundary(ScreenSize).Point2, Arr.Last.RayToBoundary(ScreenSize).Point2, Arr.Last.Point2})                   Into ToArray        Return geos.Union    End Function

 public unsafe void AddThree(__arglist) {    var args = new ArgIterator(__arglist);    var a = (byte*)TypedReference.ToObject(args.GetNextArg());    *a+=3; }

Java

// TODO: 自己重新写吧。直接转换这种代码反而浪费时间！

我还要上课呢，这次就写到这里吧。喜欢Java的可以找出描述不合理的地方，但是请勿喷。