android dp和px转换

public class DensityUtils {    /**     * dp转px     */    public static int dp2px(Context ctx, float dp) {        float density = ctx.getResources().getDisplayMetrics().density;        int px = (int) (dp * density + 0.5f);// 4.9->5 4.4->4        return px;    }    public static float px2dp(Context ctx, int px) {        float density = ctx.getResources().getDisplayMetrics().density;        float dp = px / density;        return dp;    }}