尝试与 android studio 中的 jsoup 连接时，模拟器应用程序崩溃

Question

There are no errors when running and compiling the code in android studio, but after pressing the button to connect with jsoup the app just crashes for some reason. Anyone know what I'm doing wrong?

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }


    class JsoupParseTask extends AsyncTask<String, Void, Document> {

        protected Document doInBackground(String... urls) {

            Document doc = null;
            try {
                doc = Jsoup.connect("http://google.com/").get();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }

            return doc;
        }
    }

    public void connect(View v) {

        // Call from here, it will execute doInBackground
        new JsoupParseTask().execute();
    }


}

Answer 1

It's simply an exception typed NetworkOnMainThreadException , that is thrown when an application attempts to perform a networking operation on its main thread.

As for example, try to run your code in AsyncTask:

class JsoupParseTask extends AsyncTask<String, Void, Document> {

    @Override
    protected Document doInBackground(String... urls) {

        Document doc = null;
        try {
            doc = Jsoup.connect("http://google.com/").get();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        return doc;
    }

    @Override    
    protected void onPostExecute(Document doc) { 
        // execution of result here 

        String title = doc.title();
    }

}

And call this like below:

public void connect(View v) {

    // Call from here, it will execute doInBackground
    new JsoupParseTask().execute();
}

Besides this don't forget to add internet permission in AndroidManifest.xml

<uses-permission android:name="android.permission.INTERNET" />

But since AsyncTask is deprecated, you could try it's alternative. Here is a nice tutorial that mentioned some alternatives of AsyncTask