title: constructor ImageLoader(Context) is undefined / constructor ImageLoader() is not visible
body: <p>I am getting the following error "constructor ImageLoader(Context) is undefined" at this line.</p>
  
  <pre><code>imageLoader=new ImageLoader(activity.getApplicationContext());
  </code></pre>
  
  <p>If i change it to </p>
  
  <pre><code>imageLoader=new ImageLoader();
  </code></pre>
  
  <p>it tells me that "constructor ImageLoader() is not visible"</p>
  
  <p>What am i doing wrong?</p>
  
  <p>Here is the <strong>Gallerie.java</strong> where i call the LazyAdapter
  </p>
  
  <pre><code>package com.example.androidhive;
  
  import com.example.androidhive.R;
  import android.app.Activity;
  import android.os.Bundle;
  import android.view.View;
  import android.view.View.OnClickListener;
  import android.widget.Button;
  import android.widget.ListView;
  
  
  public class Gallerie extends Activity {    ListView list;
  LazyAdapter adapter;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.gallerie);
  
      list=(ListView)findViewById(R.id.list);
      adapter=new LazyAdapter(this, mStrings);
      list.setAdapter(adapter);
  
      Button b=(Button)findViewById(R.id.button1);
      b.setOnClickListener(listener);
  }
  
  @Override
  public void onDestroy()
  {
      list.setAdapter(null);
      super.onDestroy();
  }
  
  public OnClickListener listener=new OnClickListener(){
      @Override
      public void onClick(View arg0) {
          adapter.imageLoader.clearDiscCache();
          adapter.imageLoader.clearMemoryCache();
          adapter.notifyDataSetChanged();
      }
  };
  
  private String[] mStrings={
          "http://feuerwehr-alfter.de/images/com_reports/gallery/IMG_3036_551.jpg",
          "http://feuerwehr-alfter.de/images/com_reports/gallery/IMG_0881_550.jpg",
          "http://feuerwehr-alfter.de/images/com_reports/gallery/IMG_0894_550.jpg",
  
  };
  }
  </code></pre>
  
  <p>here is my <strong>LazyAdapter.java</strong> which shows the error
  </p>
  
  <pre><code>package com.example.androidhive;
  
  import com.nostra13.universalimageloader.core.ImageLoader;
  import com.example.androidhive.R;
  import android.app.Activity;
  import android.content.Context;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.ViewGroup;
  import android.widget.BaseAdapter;
  import android.widget.ImageView;
  import android.widget.TextView;
  
  public class LazyAdapter extends BaseAdapter {
  
      private Activity activity;
      private String[] data;
      private static LayoutInflater inflater=null;
      public ImageLoader imageLoader; 
  
      public LazyAdapter(Activity a, String[] d) {
          activity = a;
          data=d;
          inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          imageLoader=new ImageLoader(activity.getApplicationContext());
      }
  
      public int getCount() {
          return data.length;
      }
  
      public Object getItem(int position) {
          return position;
      }
  
      public long getItemId(int position) {
          return position;
      }
  
      public View getView(int position, View convertView, ViewGroup parent) {
          View vi=convertView;
          if(convertView==null)
              vi = inflater.inflate(R.layout.item, null);
  
          ImageView image=(ImageView)vi.findViewById(R.id.image);
          imageLoader.displayImage(data[position], image);
          return vi;
      }
  }
  </code></pre>
  
  <p>And here the <strong>ImageLoader.java</strong> where the constructor for the ImageLoader is in.
  </p>
  
  <pre><code>package com.example.androidhive;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.HttpURLConnection;
  import java.net.URL;
  import java.util.Collections;
  import java.util.Map;
  import java.util.WeakHashMap;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import com.example.androidhive.R;
  import android.os.Handler;
  import android.content.Context;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.widget.ImageView;
  
  public class ImageLoader {
  
      MemoryCache memoryCache=new MemoryCache();
      FileCache fileCache;
      private Map&lt;ImageView, String&gt; imageViews=Collections.synchronizedMap(new WeakHashMap&lt;ImageView, String&gt;());
      ExecutorService executorService;
      Handler handler=new Handler();//handler to display images in UI thread
  
      public ImageLoader(Context context){
          fileCache=new FileCache(context);
          executorService=Executors.newFixedThreadPool(5);
      }
  
      final int stub_id=R.drawable.stub;
      public void DisplayImage(String url, ImageView imageView)
      {
          imageViews.put(imageView, url);
          Bitmap bitmap=memoryCache.get(url);
          if(bitmap!=null)
              imageView.setImageBitmap(bitmap);
          else
          {
              queuePhoto(url, imageView);
              imageView.setImageResource(stub_id);
          }
      }
  
      private void queuePhoto(String url, ImageView imageView)
      {
          PhotoToLoad p=new PhotoToLoad(url, imageView);
          executorService.submit(new PhotosLoader(p));
      }
  
      private Bitmap getBitmap(String url) 
      {
          File f=fileCache.getFile(url);
  
          //from SD cache
          Bitmap b = decodeFile(f);
          if(b!=null)
              return b;
  
          //from web
          try {
              Bitmap bitmap=null;
              URL imageUrl = new URL(url);
              HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
              conn.setConnectTimeout(30000);
              conn.setReadTimeout(30000);
              conn.setInstanceFollowRedirects(true);
              InputStream is=conn.getInputStream();
              OutputStream os = new FileOutputStream(f);
              Utils.CopyStream(is, os);
              os.close();
              conn.disconnect();
              bitmap = decodeFile(f);
              return bitmap;
          } catch (Throwable ex){
             ex.printStackTrace();
             if(ex instanceof OutOfMemoryError)
                 memoryCache.clear();
             return null;
          }
      }
  
      //decodes image and scales it to reduce memory consumption
      private Bitmap decodeFile(File f){
          try {
              //decode image size
              BitmapFactory.Options o = new BitmapFactory.Options();
              o.inJustDecodeBounds = true;
              FileInputStream stream1=new FileInputStream(f);
              BitmapFactory.decodeStream(stream1,null,o);
              stream1.close();
  
              //Find the correct scale value. It should be the power of 2.
              final int REQUIRED_SIZE=70;
              int width_tmp=o.outWidth, height_tmp=o.outHeight;
              int scale=1;
              while(true){
                  if(width_tmp/2&lt;REQUIRED_SIZE || height_tmp/2&lt;REQUIRED_SIZE)
                      break;
                  width_tmp/=2;
                  height_tmp/=2;
                  scale*=2;
              }
  
              //decode with inSampleSize
              BitmapFactory.Options o2 = new BitmapFactory.Options();
              o2.inSampleSize=scale;
              FileInputStream stream2=new FileInputStream(f);
              Bitmap bitmap=BitmapFactory.decodeStream(stream2, null, o2);
              stream2.close();
              return bitmap;
          } catch (FileNotFoundException e) {
          } 
          catch (IOException e) {
              e.printStackTrace();
          }
          return null;
      }
  
      //Task for the queue
      private class PhotoToLoad
      {
          public String url;
          public ImageView imageView;
          public PhotoToLoad(String u, ImageView i){
              url=u; 
              imageView=i;
          }
      }
  
      class PhotosLoader implements Runnable {
          PhotoToLoad photoToLoad;
          PhotosLoader(PhotoToLoad photoToLoad){
              this.photoToLoad=photoToLoad;
          }
  
          @Override
          public void run() {
              try{
                  if(imageViewReused(photoToLoad))
                      return;
                  Bitmap bmp=getBitmap(photoToLoad.url);
                  memoryCache.put(photoToLoad.url, bmp);
                  if(imageViewReused(photoToLoad))
                      return;
                  BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
                  handler.post(bd);
              }catch(Throwable th){
                  th.printStackTrace();
              }
          }
      }
  
      boolean imageViewReused(PhotoToLoad photoToLoad){
          String tag=imageViews.get(photoToLoad.imageView);
          if(tag==null || !tag.equals(photoToLoad.url))
          return true;
          return false;
      }
  
      //Used to display bitmap in the UI thread
      class BitmapDisplayer implements Runnable
      {
          Bitmap bitmap;
          PhotoToLoad photoToLoad;
          public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
          public void run()
          {
              if(imageViewReused(photoToLoad))
                  return;
              if(bitmap!=null)
                  photoToLoad.imageView.setImageBitmap(bitmap);
              else
                  photoToLoad.imageView.setImageResource(stub_id);
          }
      }
  
      public void clearCache() {
          memoryCache.clear();
          fileCache.clear();
      }
  
  }
  </code></pre>