How to get the screen density programmatically in android?
I mean: How to find the screen dpi of the current device?
This should help on your activity ...
void printSecreenInfo(){
    Display display = getWindowManager().getDefaultDisplay();
    DisplayMetrics metrics = new DisplayMetrics();
    display.getMetrics(metrics);
    Log.i(TAG, "density :" +  metrics.density);
    // density interms of dpi
    Log.i(TAG, "D density :" +  metrics.densityDpi);
    // horizontal pixel resolution
    Log.i(TAG, "width pix :" +  metrics.widthPixels);
     // actual horizontal dpi
    Log.i(TAG, "xdpi :" +  metrics.xdpi);
    // actual vertical dpi
    Log.i(TAG, "ydpi :" +  metrics.ydpi);
}
OUTPUT :
I/test( 1044): density :1.0
I/test( 1044): D density :160
I/test( 1044): width pix :800
I/test( 1044): xdpi :160.0
I/test( 1044): ydpi :160.42105
Yet another answer:
/**
* @return "ldpi", "mdpi", "hdpi", "xhdpi", "xhdpi", "xxhdpi", "xxxhdpi", "tvdpi", or "unknown".
*/
public static String getDensityBucket(Resources resources) {
    switch (resources.getDisplayMetrics().densityDpi) {
        case DisplayMetrics.DENSITY_LOW:
            return "ldpi";
        case DisplayMetrics.DENSITY_MEDIUM:
            return "mdpi";
        case DisplayMetrics.DENSITY_HIGH:
            return "hdpi";
        case DisplayMetrics.DENSITY_XHIGH:
            return "xhdpi";
        case DisplayMetrics.DENSITY_XXHIGH:
            return "xxhdpi";
        case DisplayMetrics.DENSITY_XXXHIGH:
            return "xxxhdpi";
        case DisplayMetrics.DENSITY_TV:
            return "tvdpi";
        default:
            return "unknown";
    }
}
This also works:
 getResources().getDisplayMetrics().density;
This will give you:
0.75 - ldpi
1.0 - mdpi
1.5 - hdpi
2.0 - xhdpi
3.0 - xxhdpi
4.0 - xxxhdpi

ref: density
ref 2
Blundell's answer as a static helper method:
private static String getDensityName(Context context) {
    float density = context.getResources().getDisplayMetrics().density;
    if (density >= 4.0) {
        return "xxxhdpi";
    }
    if (density >= 3.0) {
        return "xxhdpi";
    }
    if (density >= 2.0) {
        return "xhdpi";
    }
    if (density >= 1.5) {
        return "hdpi";
    }
    if (density >= 1.0) {
        return "mdpi";
    }
    return "ldpi";
}
Actualy if you want to have the real display dpi the answer is somewhere in between if you query for display metrics:
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
int dpiClassification = dm.densityDpi;
float xDpi = dm.xdpi;
float yDpi = dm.ydpi;
densityDpi * 160 will give you the values/suggestion which density you should use
0.75 - ldpi - 120 dpi
1.0 - mdpi - 160 dpi
1.5 - hdpi - 240 dpi
2.0 - xhdpi - 320 dpi
3.0 - xxhdpi - 480 dpi
4.0 - xxxhdpi - 640 dpi
as specified in previous posts
but dm.xdpi won't give you always the REAL dpi of given display:
Example:
Device: Sony ericsson xperia mini pro (SK17i)
Density: 1.0 (e.g. suggests you use 160dpi resources)
xdpi: 193.5238
Real device ppi is arround 193ppi
Device: samsung GT-I8160 (Samsung ace 2)
Density 1.5 (e.g. suggests you use 240dpi resources)
xdpi 160.42105
Real device ppi is arround 246ppi
so maybe real dpi of the display should be Density*xdpi .. but i'm not sure if this is the correct way to do!
public static String getDensity(Context context) {
    String r;
    DisplayMetrics metrics = new DisplayMetrics();
    if (!(context instanceof Activity)) {
        r = "hdpi";
    } else {
        Activity activity = (Activity) context;
        activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
        if (metrics.densityDpi <= DisplayMetrics.DENSITY_LOW) {
            r = "ldpi";
        } else if (metrics.densityDpi <= DisplayMetrics.DENSITY_MEDIUM) {
            r = "mdpi";
        } else {
            r = "hdpi";
        }
    }
    return r;
}