I sitting and trying to make some exercises with Android. My point for today is to make simple application which will download data (images from URLs) and show them in ImageView control in the layout. I saw some examples on the web and have done my app. Everything seems to be ok but when I push the button I starts its job but then fails showing error : NULL POINTER 9error reading file). Here is my code:
package com.example.htmlcontent;
import java.io.BufferedInputStream;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.Button;
import android.widget.ImageView;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
private ImageView mImageView;
private ImageView mImageView2;
public Button button;
public static ArrayList<Drawable> drawable;
public static String[] URLs = {"http://zitterman.com/wp-content/uploads/2013/07/19194927_1371972212.jpg","http://i.imgur.com/CQzlM.jpg"};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mImageView = (ImageView) findViewById(R.id.test_image);
mImageView2 = (ImageView) findViewById(R.id.test_image2);
button = (Button) findViewById(R.id.download1);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
new DownloadImage().execute();
}
});
}
/**
* Simple functin to set a Drawable to the image View
* @param drawable
*/
@SuppressWarnings("deprecation")
private void setImage()
{
if(drawable.get(0) == null)
{
System.out.println("DRAWABLE JEST NULL");
}
mImageView.setBackgroundDrawable(drawable.get(0));
mImageView2.setBackgroundDrawable(drawable.get(1));
}
public class DownloadImage extends AsyncTask<Void, Void, Void> {
/**
* Called after the image has been downloaded
* -> this calls a function on the main thread again
*/
protected void onPostExecute(Drawable image)
{
setImage();
}
protected void onPreExecute()
{
Log.i("333333", "Uruchamiam WATEK SCIAGANIA ASYNCTASKIEM PLIKU Z NETA");
}
@Override
protected Void doInBackground(Void... params) {
downloadImage();
return null;
}
/**
* Actually download the Image from the _url
* @param _url
* @return
*/
@SuppressWarnings("deprecation")
private void downloadImage()
{
//Prepare to download image
URL url;
InputStream in;
BufferedInputStream buf;
//BufferedInputStream buf;
for(int i = 0; i<URLs.length; i++)
{
try {
url = new URL(URLs[i]);
in = url.openStream();
// Read the inputstream
buf = new BufferedInputStream(in);
// Convert the BufferedInputStream to a Bitmap
Bitmap bMap = BitmapFactory.decodeStream(buf);
if (in != null) {
in.close();
}
if (buf != null) {
buf.close();
}
drawable.add(new BitmapDrawable(bMap));
} catch (Exception e) {
Log.e("Error reading file", e.toString());
}
}
}
}
}
and my XML file layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button
android:id="@+id/download1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
<TextView
android:layout_width="102dp"
android:layout_height="wrap_content"
android:text="hello" />
<ImageView
android:id="@+id/test_image"
android:layout_width="match_parent"
android:layout_height="200dp"
android:background="@drawable/ic_launcher" />
<ImageView
android:id="@+id/test_image2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/ic_launcher" />
</LinearLayout>
I have made as you see in code ArrayList which is Drawable list. No error in code. Only that NULL POINTERs.
