mmarinchenko
commented
3 years ago I tried to overcome this by implementing a subclass of ObjectDetectorOptionsBase which has its own nested protected internal abstract class Builder with required methods.
Result looks odd... I had to implement 2 nested classes for that:
- one as private implementation of protected abstract
Builderwhich required forObjectDetectorOptionsBaseconstructor - and another one as public wrapper to expose API to consumers of new subclass
DetectorOptions.cs (click to expand)
```csharp public sealed class DetectorOptions : ObjectDetectorOptionsBase // Java.Lang.Object type { private DetectorOptions(BaseBuilder baseBuilder) : base(baseBuilder) { } private sealed class BaseBuilder : ObjectDetectorOptionsBase.Builder // Java.Lang.Object type { private readonly Builder _builder; public BaseBuilder(Builder builder) => _builder = builder; protected override ObjectDetectorOptionsBase Build() => _builder.Build(); } new public sealed class Builder // pure managed type, hides base.Builder { private readonly BaseBuilder _baseBuilder; private readonly DetectorOptions _detectorOptions; public Builder() { _baseBuilder = new BaseBuilder(this); _detectorOptions = new DetectorOptions(_baseBuilder); } public Builder SetDetectorMode(int detectorMode) { _baseBuilder.SetDetectorMode(detectorMode); return this; } public Builder SetExecutor(IExecutor executor) { _baseBuilder.SetExecutor(executor); return this; } public Builder EnableClassification() { _baseBuilder.EnableClassification(); return this; } public Builder EnableMultipleObjects() { _baseBuilder.EnableMultipleObjects(); return this; } public DetectorOptions Build() => _detectorOptions; } } ```So now I can write this in C# and it compiles fine:
var options = new DetectorOptions.Builder()
.SetDetectorMode(ObjectDetectorOptionsBase.SingleImageMode)
.EnableMultipleObjects()
.EnableClassification() // Optional
.Build();But unfortunately this doesn't compile in Java due to DetectorOptions.BaseBuilder is translated into a separate public class which does not have access to the nested protected ObjectDetectorOptionsBase.Builder:
Output (click to expand)
``` 1> 2 errors 1>...\DetectorOptions_BaseBuilder.java(5,67): javac.exe error JAVAC0000: error: Builder has protected access in ObjectDetectorOptionsBase 1>...\DetectorOptions_BaseBuilder.java(5,67): javac.exe error JAVAC0000: extends com.google.mlkit.vision.objects.ObjectDetectorOptionsBase.Builder 1>...\DetectorOptions_BaseBuilder.java(5,67): javac.exe error JAVAC0000: 1>...\DetectorOptions_BaseBuilder.java(22,7): javac.exe error JAVAC0000: error: cannot find symbol 1>...\DetectorOptions_BaseBuilder.java(22,7): javac.exe error JAVAC0000: if (getClass () == DetectorOptions_BaseBuilder.class) 1>...\DetectorOptions_BaseBuilder.java(22,7): javac.exe error JAVAC0000: symbol: method getClass() 1>...\DetectorOptions_BaseBuilder.java(22,7): javac.exe error JAVAC0000: location: class DetectorOptions_BaseBuilder ```DetectorOptions_BaseBuilder.java (click to expand)
```java package crc641d15e8c705d2fdbc; public class DetectorOptions_BaseBuilder extends com.google.mlkit.vision.objects.ObjectDetectorOptionsBase.Builder // first compilation error implements mono.android.IGCUserPeer { /** @hide */ public static final String __md_methods; static { __md_methods = "n_build:()Lcom/google/mlkit/vision/objects/ObjectDetectorOptionsBase;:GetBuildHandler\n" + ""; mono.android.Runtime.register ("MSSLink.CameraApp.Detection.DetectorOptions+BaseBuilder, MSSLink.CameraApp", DetectorOptions_BaseBuilder.class, __md_methods); } public DetectorOptions_BaseBuilder () { super (); if (getClass () == DetectorOptions_BaseBuilder.class) // second compilation error mono.android.TypeManager.Activate ("MSSLink.CameraApp.Detection.DetectorOptions+BaseBuilder, MSSLink.CameraApp", "", this, new java.lang.Object[] { }); } public com.google.mlkit.vision.objects.ObjectDetectorOptionsBase build () { return n_build (); } private native com.google.mlkit.vision.objects.ObjectDetectorOptionsBase n_build (); private java.util.ArrayList refList; public void monodroidAddReference (java.lang.Object obj) { if (refList == null) refList = new java.util.ArrayList (); refList.add (obj); } public void monodroidClearReferences () { if (refList != null) refList.clear (); } } ```Is there a way to translate a nested Java.Lang.Object type written in C# to a nested class in Java while preserving the access modifiers?
AlexDevMobile
moljac
tomkulaga
alexgg94
Xamarin.Android Version:
11.1.0.26 (Visual Studio Community 2019 v16.8.5)
Operating System & Version:
Windows 10 Home Single Language 20H2 v19042.804
Google Play Services Version
117.6.0 with AndroidX dependencies
Relevant information
Packages used:
Google ML Kit Object Detection Guide with Kotlin and Java samples:
Related Google ML Kit docs:
Minimal Repro Code Sample
Get the following Java code from Google ML Kit Object Detection Guide (link provided above):
and write it in C#:
This will not compile because all
Builder's methods are missing, exceptBuild().