The * character converts to true, everything else to false.
This answer shows how to convert to Boolean[], but I seek to convert to an array of scalar booleans.
java8 lambda: convert a String of 0's and 1's to basic array of booleans
2 Answers
If the requirements are simply to convert to the described boolean array and to use streams, you can do it like this:
boolean[] result = new boolean[string.length()];
IntStream.range(0, string.length()).forEach(n -> result[n] = (string.charAt(n)=='*'));
Comments
Consider using a BitSet instead, which is the more efficient storage structure
BitSet bs = IntStream.range(0, string.length())
.filter(i -> string.charAt(i)=='*')
.collect(BitSet::new, BitSet::set, BitSet::or);
You can test the bits using bs.get(index), which is not worse than array[index].
Note that a BitSet also has a stream() method which produces an IntStream of the indices of true value, equivalent to the stream we used for constructing the BitSet. So if you can’t get away without an array at some point, you could create it like
boolean[] array = new boolean[string.length()];
bs.stream().forEach(i -> array[i]=true);
1 Comment
fps
Holger, I was terribly slow with this question (actually I'm having a SO break), but I had in mind exactly this.
collectingAndThen(toList(), boxedBooleanListToArray)or the like.Boolean[]or aList<Boolean>and then converting that to a primitiveboolean[], and you'll have to write that part yourself (or get it from a third-party library).booleanprimitive type is a waste of resources. It's much better to use aBitSet. Do you need aboolean[]for any special reason?