dpでマージンを指定する場合は、この方法を使用できます。
private void addMarginsInDp(View view, int leftInDp, int topInDp, int rightInDp, int bottomInDp) {
DisplayMetrics dm = view.getResources().getDisplayMetrics();
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
lp.setMargins(convertDpToPx(leftInDp, dm), convertDpToPx(topInDp, dm), convertDpToPx(rightInDp, dm), convertDpToPx(bottomInDp, dm));
view.setLayoutParams(lp);
}
private int convertDpToPx(int dp, DisplayMetrics displayMetrics) {
float pixels = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, displayMetrics);
return Math.round(pixels);
}