how to make background transparent in android studio code example

Example 1: how to make background image transparent in android studio

android:backgroundTint="#80FFFFFF"
android:backgroundTintMode="src_over"
>>for setting background as transparent in android studio(only bg)
android:alpha="0.4"
>>for all views

Example 2: android java transparent background

100% — FF
95% — F2
90% — E6
85% — D9
80% — CC
75% — BF
70% — B3
65% — A6
60% — 99
55% — 8C
50% — 80
45% — 73
40% — 66
35% — 59
30% — 4D
25% — 40
20% — 33
15% — 26
10% — 1A
5% — 0D
0% — 00