public class TypedValueApiUseDemoActivity extends AppCompatActivity {

    public static final String TAG = "xp.chen";

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_typed_value_api_use_demo);

        int dipValue = 20;

        float density = getResources().getDisplayMetrics().density;

        int finalPx = (int) (dipValue * density);

        int pxValue = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dipValue, getResources().getDisplayMetrics());

        Log.i(TAG, "finalPx: "+finalPx+", pxValue: "+pxValue);

    }

}

/**

     * Converts an unpacked complex data value holding a dimension to its final floating

     * point value. The two parameters <var>unit</var> and <var>value</var>

     * are as in {@link #TYPE_DIMENSION}.

     *

     * @param unit The unit to convert from.

     * @param value The value to apply the unit to.

     * @param metrics Current display metrics to use in the conversion --

     *                supplies display density and scaling information.

     *

     * @return The complex floating point value multiplied by the appropriate

     * metrics depending on its unit.

     */

    public static float applyDimension(int unit, float value,

                                       DisplayMetrics metrics)

    {

        switch (unit) {

        case COMPLEX_UNIT_PX:

            return value;

        case COMPLEX_UNIT_DIP:

            return value * metrics.density;

        case COMPLEX_UNIT_SP:

            return value * metrics.scaledDensity;

        case COMPLEX_UNIT_PT:

            return value * metrics.xdpi * (1.0f/72);

        case COMPLEX_UNIT_IN:

            return value * metrics.xdpi;

        case COMPLEX_UNIT_MM:

            return value * metrics.xdpi * (1.0f/25.4f);

        }

        return 0;

    }