How to check an Android device is HDPI screen or MDPI screen?

density = getResources().getDisplayMetrics().density;// return 0.75 if it's LDPI// return 1.0 if it's MDPI// return 1.5 if it's HDPI// return 2.0 if it's XHDPI// return 3.0 if it's XXHDPI// return 4.0 if it's XXXHDPI

You can check the screen density with:

switch (getResources().getDisplayMetrics().densityDpi) {case DisplayMetrics.DENSITY_LOW:    // ...    break;case DisplayMetrics.DENSITY_MEDIUM:    // ...    break;case DisplayMetrics.DENSITY_HIGH:    // ...    break;case DisplayMetrics.DENSITY_XHIGH:    // ...    break;}

EDIT Be aware that as Android evolves, other values should be included in the switch cases. As of this edit, this includes DisplayMetrics.DENSITY_TV and DisplayMetrics.DENSITY_XXHIGH. Consult the docs for the latest info; I'm not going to bother maintaining this answer.

As of 2018, you can use the below method -

    public static String getDeviceDensityString(Context context) {    switch (context.getResources().getDisplayMetrics().densityDpi) {        case DisplayMetrics.DENSITY_LOW:            return "ldpi";        case DisplayMetrics.DENSITY_MEDIUM:            return "mdpi";        case DisplayMetrics.DENSITY_TV:        case DisplayMetrics.DENSITY_HIGH:            return "hdpi";        case DisplayMetrics.DENSITY_260:        case DisplayMetrics.DENSITY_280:        case DisplayMetrics.DENSITY_300:        case DisplayMetrics.DENSITY_XHIGH:            return "xhdpi";        case DisplayMetrics.DENSITY_340:        case DisplayMetrics.DENSITY_360:        case DisplayMetrics.DENSITY_400:        case DisplayMetrics.DENSITY_420:        case DisplayMetrics.DENSITY_440:        case DisplayMetrics.DENSITY_XXHIGH:            return "xxhdpi";        case DisplayMetrics.DENSITY_560:        case DisplayMetrics.DENSITY_XXXHIGH:            return "xxxhdpi";    }}

But as @Ted pointed always consult the official docs before using