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

Question

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

From the above answers, I combined them and created the below function:

    public static String getDeviceDensity(Context context){
    String deviceDensity = "";
    switch (context.getResources().getDisplayMetrics().densityDpi) {
        case DisplayMetrics.DENSITY_LOW:
            deviceDensity =  0.75 + " ldpi";
            break;
        case DisplayMetrics.DENSITY_MEDIUM:
            deviceDensity =  1.0 + " mdpi";
            break;
        case DisplayMetrics.DENSITY_HIGH:
            deviceDensity =  1.5 + " hdpi";
            break;
        case DisplayMetrics.DENSITY_XHIGH:
            deviceDensity =  2.0 + " xhdpi";
            break;
        case DisplayMetrics.DENSITY_XXHIGH:
            deviceDensity =  3.0 + " xxhdpi";
            break;
        case DisplayMetrics.DENSITY_XXXHIGH:
            deviceDensity =  4.0 + " xxxhdpi";
            break;
        default:
            deviceDensity = "Not found";
    }
    return deviceDensity;
}

Now, on which device you want to get the density information and which folder it will be used, just add the above method in that activity and add the below line in onCreate

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    Log.d("Screen Density: ", Helper.getDeviceDensity(this));

}