[java]
package de.clarisweb.android.jsondemo;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

public class DownloadTask extends AsyncTask< String, Void, String> {

@Override
protected String doInBackground(String… urls) {

String result = "";
URL url;
HttpURLConnection urlConnection= null;

try {
url = new URL(urls[0]);
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();

while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();

}

return result;

} catch (Exception e){

e.printStackTrace();
return null;
}
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);

Log.i ("JSON: ", s);

}
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action",Snackbar.LENGTH_LONG)
.setAction("Action", null).show();

}
});

DownloadTask task = new DownloadTask();
//
task.execute("http://headers.jsontest.com/");

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();

if (id == R.id.action_settings) {
return true;
}

return super.onOptionsItemSelected(item);
}
}

[/java]