Add the following dependency to the build.gradle file:

compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.5'

Add the following permissions to the AndroidManifest.xml file:

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

Initialize the Universal Image Loader. This must be done before the first usage:

ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this)
    // ...
    .build();
ImageLoader.getInstance().init(config);

The full configuration options can be found here.

Load an image, decode it into a bitmap, and display the bitmap in an ImageView (or any other view which implements the ImageAware interface):

ImageLoader.getInstance().displayImage(imageUri, imageView);

Load an image, decode it into a bitmap, and return the bitmap to a callback:

ImageLoader.getInstance().loadImage(imageUri, new SimpleImageLoadingListener() {
    @Override
    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
        // Do whatever you want with the bitmap.
    }
});

Load an image, decode it into a bitmap and return the bitmap synchronously:

Bitmap bmp = ImageLoader.getInstance().loadImageSync(imageUri);