The Google Nexus 10 comes out shortly, and is the first device to use xxhdpi resources. It sports a display density of about 300 DPI (according to the Nexus 10 website and this calculator).
However, when I go to the Android documentation, it states:
ldpi: ~120dpimdpi: ~160dpihdpi: ~240dpixhdpi: ~320dpixxhdpiis not specified.
How come the Nexus 10's 300 DPI screen is xxhdpi instead of xhdpi, and what should be the approximate DPI of xxhdpi? Should we even worry about having new resources (aside from icons) for xxhdpi at this point, or should we just let the OS scale up xhdpi resources?
According to the post linked in the G+ resource:
The gorgeous screen on the Nexus 10 falls into the XHDPI density bucket. On tablets, Launcher uses icons from one density bucket up [0] to render them slightly larger. To ensure that your launcher icon (arguably your apps most important asset) is crisp you need to add a 144*144px icon in the drawable-xxhdpi or drawable-480dpi folder.
So it looks like the xxhdpi is set for 480dpi. According to that, tablets use the assets from one dpi bucket higher than the one they're in for the launcher. The Nexus 10 being in bucket xhdpi will pull the launcher icon from the xxhdpi.
Also, was not aware that tablets take resources from the asset bucket above their level. Noted.
xxhdpi was not specified before but now new devices S4, HTC one are surely comes inside xxhdpi .These device dpi are around 440. I do not know exact limit for xxhdpi See how to develop android application for xxhdpi device Samsung S4 I know this is late answer but as thing had change since the question asked
Note Google Nexus 10 need to add a 144*144px icon in the drawable-xxhdpi or drawable-480dpi folder.
The DPI of the screen of the Nexus 10 is ±300, which is in the unofficial xhdpi range of 280‑400.
Usually, devices use resources designed for their density. But there are exceptions, and exceptions might be added in the future.
The Nexus 10 uses xxhdpi resources when it comes to launcher icons.
The standard quantised DPI for xxhdpi is 480 (which means screens with a DPI somewhere in the range of 400‑560 are probably xxhdpi).
480 dpi is the standard QUANTIZED resolution for xxhdpi, it can vary something less (i.e.: 440 dpi) or more (i.e.: 520 dpi). Scale factor: 3x (3 * mdpi).
Now there's a higher resolution, xxxhdpi (640 dpi). Scale factor 4x (4 * mdpi).
Here's the source reference.
The resolution is 480 dpi, the launcher icon is 144*144px all is scaled 3x respect to mdpi (so called "base", "baseline" or "normal") sizes.
The newer android phones in the market like HTC one, Xperia Z etc have resolutions in the >480dpi range, putting them in the new xxhdpi class as well. The new assets might be useful for them too.
A set of four generalized sizes: small, normal, large, and xlarge Note: Beginning with Android 3.2 (API level 13), these size groups are deprecated in favor of a new technique for managing screen sizes based on the available screen width. If you're developing for Android 3.2 and greater, see Declaring Tablet Layouts for Android 3.2 for more information.
A set of six generalized densities:
ldpi (low) ~120dpi
mdpi (medium) ~160dpi
hdpi (high) ~240dpi
xhdpi (extra-high) ~320dpi
xxhdpi (extra-extra-high) ~480dpi
xxxhdpi (extra-extra-extra-high) ~640dpi
From developer.android.com : http://developer.android.com/guide/practices/screens_support.html
来源：https://stackoverflow.com/questions/13215587/android-xxhdpi-resources