How to convert a String to a searchable Array in dart? - flutter

Question

I have a String like Lion is the king I need to split it in such a way that it returns an array like this :
L
Li
Lio
Lion
""
i
is
""
t
th
the
""
k
ki
kin
king
My CODE :
List<String> splitList = name.split(' ');
List<String> indexList = [];
for (int i = 0; i < splitList.length; i++,) {
for (int j = 0; j < splitList[i].length; j++) {
indexList.add(splitList[i].substring(0, j).toLowerCase());
}
}
return indexList;
Here name is a String.
Result of the above code:
L
Li
Lio
""
i
""
t
th
""
k
ki
kin
Problem with my code :
In my code the last alphabet of every word is missing.
Uses of this:
I am using this for searching purposes, in short I am saving this array in Firestore and create a searching function using array contains: in StreamBuilder

Answer 1

By adding one to the splitList[i].length it should works:
String name = "Lion is the king";
List<String> splitList = name.split(' ');
List<String> indexList = [];
for (int i = 0; i < splitList.length; i++,) {
for (int j = 0; j < splitList[i].length + 1; j++) {
indexList.add(splitList[i].substring(0, j).toLowerCase());
}
}
for (var element in indexList){
print("\n $element");
}
//return indexList

Answer 2

use split to every char
String name = "Lion is the king";
var res = List<String>();
var word = '';
name.split('').forEach((char) {
word = (char.isEmpty) ? '': word + char.toLowerCase();
res.add(word);
});
print(res);
output:
[l, li, lio, lion, , i, is, , t, th, the, , k, ki, kin, king]

Answer 3

The first element of your j loop is using `word.substring(0, 0) or ''.
This is why the result of your method contains an empty string before each word split:
[, l, li, lio, , i, , t, th, , k, ki, kin, king]
Your code with correction:
List<String> indexString(String name) {
List<String> splitList = name.split(' ');
List<String> indexList = [];
for (int i = 0; i < splitList.length; i++,) {
for (int j = 0; j < splitList[i].length; j++) {
indexList.add(splitList[i].substring(0, j + 1).toLowerCase());
}
}
return indexList;
}
But, you'll also have a problem with punctuation.
Input: "Lion, he is the king!"
Output: ["l", "li", "lio", "lion", "lion,", "h", "he", "i", "is", "t", "th", "the", "k", "ki", "kin", "king", "king!"]
RegExp
Maybe you should use Regular Expressions.
void main() {
final name = "Lion, he is the king!";
print(indexString(name));
}
List<String> indexString(String name) {
RegExp regExp = new RegExp(r"(\w+)");
List<String> splitList =
regExp.allMatches(name).map((m) => m.group(0)).toList();
print(splitList);
List<String> indexList = splitList
.map(
(word) => word.split('').fold<List<String>>(
[''],
(acc, curr) => [...acc, '${acc.last}$curr'],
).sublist(1),
)
.expand((i) => i)
.toList();
return indexList;
}
Note: This will also index alphanumeric words.