Help me make my first extension

[ravigarg]

I have made my first extension in Appybulder Code Editor. But it is pointing out some bugs I have attached both the code and errors while compiling. Please help me complete it.

import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

import android.content.Context;
import android.util.Log;
import com.google.appinventor.components.annotations.*;
import com.google.appinventor.components.runtime.*;
import com.google.appinventor.components.common.ComponentCategory;

@DesignerComponent(version = 1,  description = "This Extension was created with the AppyBuilder Code Editor.<br>" + 
                   "Create your own here:<br><a href='https://editor.appybuilder.com' target='_blank'>https://editor.appybuilder.com</a><br>",
        category = ComponentCategory.EXTENSION,
        nonVisible = true,   iconName = "http://appyBuilder.com/extensions/icons/extension.png")
@SimpleObject(external = true)
@UsesPermissions(permissionNames = "android.permission.WRITE_EXTERNAL_STORAGE, android.permission.READ_EXTERNAL_STORAGE")
public class Demo1 extends AndroidNonvisibleComponent {
    private ComponentContainer container;
    /**
     * @param container container, component will be placed in
     */
    public Demo1(ComponentContainer container) {
        super(container.$form());
        this.container = container;
    }
  
   @SimpleFunction (description = "magic")
	public String Manipulation(String image,String nameoffile) {  	
  System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
		String file = image;
      String final = ""/"+nameoffile+".png"";
      Mat src = Imgcodecs.imread(file,0);
      Mat dst = new Mat();
      Imgproc.adaptiveThreshold(src, dst, 125, Imgproc.ADAPTIVE_THRESH_MEAN_C,Imgproc.THRESH_BINARY, 11, 12);
      Imgcodecs.imwrite(final, dst);
      return final;
    }
    } ```



[details="Bug Report"]
Buildfile: /projects/goldv2/appinventor-sources/appinventor/build.xml

extensions:

clean:
   [delete] Deleting directory /projects/goldv2/appinventor-sources/appinventor/build/components

BUILD FAILED
/projects/goldv2/appinventor-sources/appinventor/build.xml:34: The following error    [delete] Deleting directory /projects/goldv2/appinventor-sources/appinventor/components/reports

init:

common_CommonUtils:

init:

CommonUtils:

common_CommonVersion:

init:

CommonVersion:
     [exec] Result: 128
     [exec] Result: 128

CopyToRunLibDir:

components_AndroidRuntime:

init:
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/build/components
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/build
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/build/classes
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/reports
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/reports/raw
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/reports/html

CommonConstants:
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/build/classes/CommonConstants
    [javac] Compiling 6 source files to /projects/goldv2/appinventor-sources/appinventor/components/build/classes/CommonConstants
    [javac] warning: [options] bootstrap class path not set in conjunction with -source 1.7
    [javac] 1 warning
    [javac] Creating empty /projects/goldv2/appinventor-sources/appinventor/components/build/classes/CommonConstants/com/google/appinventor/components/common/package-info.class
      [jar] Building jar: /projects/goldv2/appinventor-sources/appinventor/build/components/CommonConstants.jar
      [jar] Building jar: /projects/goldv2/appinventor-sources/appinventor/build/components/CommonConstants-gwt.jar

HtmlEntities:
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/build/classes/HtmlEntities
    [javac] Compiling 1 source file to /projects/goldv2/appinventor-sources/appinventor/components/build/classes/HtmlEntities
    [javac] warning: [options] bootstrap class path not set in conjunction with -source 1.7
    [javac] 1 warning
      [jar] Building jar: /projects/goldv2/appinventor-sources/appinventor/components/build/HtmlEntities.jar

common_CommonVersion:

init:

CommonVersion:
     [exec] Result: 128
     [exec] Result: 128

AndroidRuntime:
    [mkdir] Created dir: /projects/goldv2/appinventor-sources/appinventor/components/build/classes/AndroidRuntime
    [javac] Compiling 332 source files to /projects/goldv2/appinventor-sources/appinventor/components/build/classes/AndroidRuntime
    [javac] warning: [options] bootstrap class path not set in conjunction with -source 1.7
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: not a statement
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]       ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: ';' expected
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]             ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: illegal start of type
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                    ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: ';' expected
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                     ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: illegal start of expression
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                        ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: ';' expected
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                         ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: illegal start of expression
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                                       ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:44: error: ';' expected
    [javac]       String final = ""/"+nameoffile+".png"";
    [javac]                                           ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:48: error: illegal start of expression
    [javac]       Imgcodecs.imwrite(final, dst);
    [javac]                         ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:48: error: ';' expected
    [javac]       Imgcodecs.imwrite(final, dst);
    [javac]                              ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:48: error: not a statement
    [javac]       Imgcodecs.imwrite(final, dst);
    [javac]                                ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:48: error: ';' expected
    [javac]       Imgcodecs.imwrite(final, dst);
    [javac]                                   ^
    [javac] /projects/goldv2/appinventor-sources/appinventor/components/src/com/appybuilder/ravigargrud/Demo1/Demo1.java:49: error: illegal start of expression
    [javac]       return final;
    [javac]              ^
    [javac] 13 errors
    [javac] 1 warning

BUILD FAILED
/projects/goldv2/appinventor-sources/appinventor/build.xml:35: The following error occurred while executing this line:
/projects/goldv2/appinventor-sources/appinventor/build-common.xml:372: The following error occurred while executing this line:
/projects/goldv2/appinventor-sources/appinventor/components/build.xml:141: The following error occurred while executing this line:
/projects/goldv2/appinventor-sources/appinventor/build-common.xml:118: Compile failed; see the compiler error output for details.

Total time: 2 seconds
[/details]

[vknow360 (Sunny Gupta)]

I think you are not familiar with Java till yet.
So I suggest you to learn Java first.

[ravigarg]

@vknow360

I think you are not familiar with Java

Yes, I know the basics but haven’t coded for last 2 years. So obviously I would need to practice to be familiar with Java again.

Still, I request, if you can help.

[ravigarg]

I’m getting this error repeatedly @vknow360
error: package org.opencv.core does not exist

[vknow360 (Sunny Gupta)]

You are using external lib which neither includes in build path nor you can add it using Appy Builder.
Use extension template instead.

[ravigarg]

Ok! Thanks for your help can you please clarify what at do you mean by?

@vknow360

Use extension template instead.

[vknow360 (Sunny Gupta)]

Use this lightweight ‘offline’ ide:

mit-cml/extension-template

[ravigarg]

Thanks for help. I will try and tell you.

[yusufcihan]

1. You typed that wrong:

   String final = ""/"+nameoffile+".png"";
   

   Needs to be:

   String final = "/" + nameoffile + ".png";
   

2. Also final is a reserved word in Java. Reserved words are used by programming language itself. You can’t use it to name your variable.

[ravigarg]

I have changed all of that but it will still not work as

@vknow360

You are using external lib which neither includes in build path nor you can add it using Appy Builder.

[vknow360 (Sunny Gupta)]

See here how to add external lib:

Third-party libraries

Hi, Is it possible to import other third-party libraries to an extension? [image] the log does say that the package does not exist [image] Is there any way to “install” these kind of libraries? Thanks.

Above topic is related to ai sources but method is same also in template.
But in template just add jar to deps dir.

[ravigarg]

@vknow360

Use this lightweight ‘offline’ ide:

Can you please help me? I dont know what I need to do.

[vknow360 (Sunny Gupta)]

Sure.

Learn how to create extensions

Hey everybody, A few days ago, I published two articles on how to develop extensions for Kodular (and, AI2). So, if you too want to get started with the extension development, these articles are definitely going to help you out: Configuring your computer to build App Inventor 2 extensions Writing your first App Inventor 2 and Kodular extension Go, check them out!

[ravigarg]

I am unable to install add environment variable for ant, even after adding when I check in Command Prompt it shows no such command ant -version

[vknow360 (Sunny Gupta)]

Have you installed Ant?
Have you correctly set path of Ant?

[Vedang (Indian boy)]

Make sure that you have edited path and ANT_HOME in system variables

[ravigarg]

@vknow360

Have you installed Ant?

How? I just unzipped the file and placed it in C drive then the gave that path in variable setting.

[vknow360 (Sunny Gupta)]

Sorry…I mean downloaded.

@ravigarg

I just unzipped the file and placed it in C drive then the gave that path in variable setting.

Then problem can be there.

[ravigarg]

[Vedang (Indian boy)]

You want to edit path