activity.java

final WallpaperManager wallpaperManager = WallpaperManager.getInstance(this);
        final Drawable wal = wallpaperManager.getDrawable();
        Bitmap bitmap = ((BitmapDrawable)wal).getBitmap();
      //  Toast.makeText(Main2Activity.this, bitmap+"", Toast.LENGTH_LONG).show();
        
        ImageView imagePreview = (ImageView)findViewById(R.id.imageView);
        imagePreview.setImageBitmap(bitmap);
                // TODO Auto-generated method stub
                WallpaperManager myWallpaperManager
                        = WallpaperManager.getInstance(getApplicationContext());
        try {
            context.setWallpaper(bit);
            Toast.makeText(Main2Activity.this,"wallpaper set", Toast.LENGTH_LONG).show();
        } catch (IOException e) {
            e.printStackTrace();
        }

       // bitmap = BitmapFactory.decodeStream(stream);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
        byte[] b = baos.toByteArray();
        String encodedImage = Base64.encodeToString(b, Base64.DEFAULT);
       // textEncode.setText(encodedImage);

        SharedPreferences shre = PreferenceManager.getDefaultSharedPreferences(this);
        SharedPreferences.Editor edit=shre.edit();
        edit.putString("image_data",encodedImage);
        edit.commit();

        String previouslyEncodedImage = shre.getString("image_data", "");

        if( !previouslyEncodedImage.equalsIgnoreCase("") ){
            b = Base64.decode(previouslyEncodedImage, Base64.DEFAULT);
           Bitmap bit = BitmapFactory.decodeByteArray(b, 0, b.length);
           // imagePreview.setImageBitmap(bit);
        }