Develop Reference

Android Performance: load images for listView

I'm going to develop an application which shows a ListView which each row have a seperate image (like personal picture for contacts list). It seems I have two options:
1- Store all images in Asset Folder and load image using setImageDrawable() command.
2- Store all images in Drawable Folder and load theme using setImageResource(R.drawable.xxx)
So my questions is does they differ in performance? And how can I speed up listView rendering such that images displayed in acceptable speed.

There should not much performance different to access image from Drawable or asset folder. You can see the answer too - > Android: Accessing images from assets/drawable folders
But, When you using ListView you are recreating the view . So, Where ever you store the image all the images are will not feel much different .

There are not so much differences. Just for coding pattern changes.
assets/
Bitmap files (.png, .9.png, .jpg, .gif) or XML files that are compiled into the following drawable resource.
drawable/
Arbitrary files to save in their raw form. To open these resources with a raw InputStream, call Resources.openRawResource() with the resource ID, which is R.raw.filename.
https://developer.android.com/guide/topics/resources/providing-resources.html#ResourceTypes

Saving run-time generated NinePatch on external memory

I'm following this post to create nine patch drawable at run-time. I need to save the 9patch image on the internal/external memory, so that i can easily retrieve it's URI and assign it to an ImageView for example. Does anybody know how can I achieve this?
P.S. Bitmap.compress method won't work, because it will save the image as a regular (not 9patch) png file.
P.S. I know that I can serialize generated NinePatch object and save it to a file. But this way I can't assign it to a RemoteViews object (using RemoteViews.setImageViewUri method). So I need to save it as a real nine patch image.

You can store the image as Bitmap and then create a NinePatch using http://developer.android.com/reference/android/graphics/NinePatch.html#NinePatch(android.graphics.Bitmap, byte[])

Android how to load Image file with different extension using Picasso

This is a different situation. I want to load a image file which has stored with different extension like 'photo.xyz' instead of 'photo.jpg or photo.png' using Picasso. to avoid image from gallery i am storing image like this. Please help me is there any option to show like this.

Neither Picasso nor Android (which does the actual image decoding) cares what the file name is. It can be anything. The type of the image is always determined from the first few bytes of the actual image data.

As a small workaround you can programmatically put .nomedia file into your app folder to prevent images to be cached by mediaserver and displayed in a Gallery app.

getting string image path placed in drawable folder

Is it possible to get the path of an image in string form in android like
res/drawable/image.png
Or is their any other way for getting string path of an image that is placed in drawable.

No, it is not.
Drawable drawable = this.getResources().getDrawable(R.drawable.ic_launcher);
e.g. will give you the default launcher icon. It is not possible to get the exact path for an image , that is stored in drawable.
Why not? When you compile your app to an *.apk file, all resources (ok, except from them in /raw) are compiled as well. You can only acces them, using their R. id.
Solution? Not really, you could copy them to a location on the sd card for example. Now you know the location :)

its not possible to get path of drawable image directly , but you can get this by storing it in internal memory or sdcard of device.For this i have written blog.. check out the link
here
i am sure it will help you.

Android Load Image from Drawable

i need to create a object Image from import javax.microedition.lcdui.Image; using a file .png placed in drawable folder. How can i do that?
Thanks

Since this Android and not JavaME, you cannot create a javax.microedition.lcdui.Image. You would create a Bitmap instead. Here's a decent tutorial on working with images in Android.