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yourView.setBackgroundColor(Color.TRANSPARENT);
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android:background="#55000000" //Black transparent
android:background="#00000000" //Transparent
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"color code" #0000
"More colors below"
#FFFF #F888 #F000 - full color
#EFFF #E888 #E000
#DFFF #D888 #D000
#CFFF #C888 #C000
#BFFF #B888 #B000
#AFFF #A888 #A000
#9FFF #9888 #9000
#8FFF #8888 #8000
#7FFF #7888 #7000
#6FFF #6888 #6000
#5FFF #5888 #5000
#4FFF #4888 #4000
#3FFF #3888 #3000
#2FFF #2888 #2000
#1FFF #1888 #1000
#0FFF #0888 #0000 - full transparency