hdpi ldpi mdpi icon/menu resolution

Question

I want to set an icon for my application, and don't know the exact resolution to put in the three folders hdpi/ldpi/mdpi . Also i want to set icons to my menu options and don't know what resolution to apply.

Thank you for your help.

Answer 1

Launcher icons

48 × 48 (mdpi)
72 × 72 (hdpi)
96 × 96 (xhdpi)
144 × 144 (xxhdpi)
192 × 192 (xxxhdpi)
512 × 512 (Google Play store).png 

Action bar, Dialog & Tab icons

24 × 24 area in 32 × 32 (mdpi)
36 × 36 area in 48 × 48 (hdpi)
48 × 48 area in 64 × 64 (xhdpi)
72 × 72 area in 96 × 96 (xxhdpi)
96 × 96 area in 128 × 128 (xxxhdpi)

.png These icons are used in the action bar menu. The first number is the size of the icon area, and the second is file size.

Notification icons

 22 × 22 area in 24 × 24 (mdpi) 
 33 × 33 area in 36 × 36 (hdpi)
 44 × 44 area in 48 × 48 (xhdpi)
 66 × 66 area in 72 × 72 (xxhdpi)
 88 × 88 area in 96 × 96 (xxxhdpi)

.png These are used to represent application notifications in the status bar. They should be flat (no gradients), white and face-on perspective

Small Contextual Icons

16 × 16 (mdpi)
24 × 24 (hdpi)
32 × 32 (xhdpi)
48 × 48 (xxhdpi)
64 × 64 (xxxhdpi)

.png Small icons are used to surface actions and/or provide status for specific items. For example, in the Gmail app, each message has a star icon that marks the message as important.

For more information, use the android developers iconography material.

http://developer.android.com/design/style/iconography.html

Answer 2

Everything you need to know is here in the official documentation.