Extension - Returning "null" Help

Extensions Extension Development
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#1

I am learning develop extensions.

but when i try it’s returning “null”
what is my wrong. Does anyone help me?

package com.ruwis.webslapper;

import java.util.ArrayList;
import java.util.List;

import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import com.google.appinventor.components.annotations.SimpleFunction;
import com.google.appinventor.components.runtime.AndroidNonvisibleComponent;
import com.google.appinventor.components.runtime.ComponentContainer;
import com.google.appinventor.components.runtime.errors.YailRuntimeError;
import com.google.appinventor.components.runtime.util.YailList;

public class WebSlapper extends AndroidNonvisibleComponent {

  public WebSlapper(ComponentContainer container) {
    super(container.$form());
  }

  
  @SimpleFunction()
  public List<String> VeriCek(String url, String css) {
	  try {
		  Connection connect = Jsoup.connect(url).userAgent("Mozilla/5.0");
		  Document liste = connect.get();
		  Elements secilen = liste.select(css);
		  return YailList.makeList(secilen);
	  }
	  catch(Exception e) {
		  return null;
	  }
  }
  
}
#2

You can’t return null, instead return an empty list.

#3

so do you see any other error?

#4

There’s no other error, except that you should return an empty list instead of null. App Inventor doesn’t respond well to null, although they should definitely add that.

1 Like
#5

I set it as empty list but it returns empty list every time. I couldn’t find my mistake

#6

Jsoup does not parse html synchronously so you need to check whether document is null or not on a regular interval.
This thing is missing in HtmlUtils extension too.

2 Likes
#7

hey this post is mine. I solved the problem as in this example.

new Thread() {
		  public void run() {
			  WebSlapper.this.activity.runOnUiThread(new Runnable() {
                  public void run() {
                	  try {
                			Document doc = Jsoup.connect(url).userAgent("Mozilla/5.0").get();
      					Elements elements = doc.select(cssSelector);
      					WebSlapped(elements);
                		}
                		catch(Exception exception) {
                			ErrorOccurred(exception.getMessage());
                		}
                  }
			  
			  
			  });
		  }
		  
	  }.start();
#8

@Peter will one day find out you have two accounts :sweat_smile:

#9

What’s wrong with having 2 accounts?

#10

Only one is allowed on the community. Which one should i delete?

1 Like
#11

Ok npb
You can delete it

#12

It means this one or the other one?

#14

Other account

#15 
package com.ruwis.webslapper;

import java.util.List;

import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;

import com.google.appinventor.components.annotations.SimpleFunction;
import com.google.appinventor.components.runtime.AndroidNonvisibleComponent;
import com.google.appinventor.components.runtime.ComponentContainer;
import com.google.appinventor.components.runtime.util.YailList;
import com.google.appinventor.components.runtime.util.AsynchUtil;

public class WebSlapper extends AndroidNonvisibleComponent {

  public WebSlapper(ComponentContainer container) {
    super(container.$form());
  }

  // Función modificada para usar un hilo separado
  @SimpleFunction
  public void VeriCek(final String url, final String css) {
    AsynchUtil.runAsynchronously(new Runnable() {
      @Override
      public void run() {
        try {
          Connection connect = Jsoup.connect(url).userAgent("Mozilla/5.0");
          Document doc = connect.get();
          Elements elements = doc.select(css);

          // Si no se encontraron elementos, devuelve explícitamente null
          if (elements.isEmpty()) {
            returnResult(null); // Retorna null explícitamente
          } else {
            returnResult(YailList.makeList(elements.eachText())); // Convierte a lista de App Inventor
          }
        } catch (Exception e) {
          returnResult(null); // En caso de error, retorna null
        }
      }
    });
  }

  // Método para retornar el resultado a App Inventor en el hilo principal
  private void returnResult(final List<String> result) {
    form.runOnUiThread(new Runnable() {
      @Override
      public void run() {
        if (result == null) {
          // Enviar null a App Inventor
          WebSlapped(null);
        } else {
          // Enviar la lista obtenida a App Inventor
          WebSlapped(result);
        }
      }
    });
  }

  // Evento para devolver el resultado a App Inventor
  @SimpleFunction
  public void WebSlapped(List<String> result) {
    // Implementa este evento para manejar los resultados en App Inventor
  }

  // Método para manejar errores
  @SimpleFunction
  public void ErrorOccurred(String errorMessage) {
    // Implementa el manejo de errores
  }
}