[英]custom sort a string list in flutter
I have a list (in flutter):我有一个列表(颤动):
loadedSummaryList = [
'BILD',
'DRIT',
'VIMN',
'WELT',
'FLUTTER',
'ALL'
];
, and I want to sort this list like: ,我想像这样对这个列表进行排序:
['WELT', 'BILD', 'VIMN', 'DRIT', 'ALL', 'FLUTTER']
in other words, I want to sort the first four elements of the list always like 'WELT', 'BILD', 'VIMN', 'DRIT', and then alphabetically.换句话说,我想对列表的前四个元素进行排序,例如“WELT”、“BILD”、“VIMN”、“DRIT”,然后按字母顺序排序。 I tried it like this:我这样试过:
List<String> sortList = ['WELT', 'BILD', 'VIMN', 'DRIT'];
loadedSummaryList.sort(
(a, b) {
int aIntex = sortList.indexOf(a.name);
int bIntex = sortList.indexOf(b.name);
return aIntex.compareTo(bIntex);
},
);
which returns返回
['ALL', 'FLUTTER', 'WELT', 'BILD', 'VIMN', 'DRIT'];
but actually, I want to have it like:但实际上,我想让它像:
['WELT', 'BILD', 'VIMN', 'DRIT', 'ALL', 'FLUTTER']
could someone help me, please?有人可以帮我吗? thanks in advance提前致谢
Just sort them and merge them into one.只需对它们进行排序并将它们合并为一个即可。
void main() {
var all = <String>['BILD', 'DRIT', 'VIMN', 'WELT', 'FLUTTER', 'ALL'];
var sort = <String>['WELT', 'BILD', 'VIMN', 'DRIT'];
// It depends on how you want list sorting in the end result.
// You can sort both lists if you want.
all.sort();
//sort.sort();
var result = sort.followedBy(all).toSet().toList();
print(result); // [WELT, BILD, VIMN, DRIT, ALL, FLUTTER]
}
First thing, indexOf
returns -1
when the element is not in the list, therefore it will put those in front.首先,当元素不在列表中时, indexOf
返回-1
,因此它将把那些放在前面。 A solution for that is to change it to a higher number in that case.解决方案是在这种情况下将其更改为更高的数字。 Secondly, you also need to sort them alphabetically, which you don't do now.其次,您还需要按字母顺序对它们进行排序,而您现在不需要这样做。 You can do that by doing a compareTo
on the strings themselves in the case that the first compareTo
returns 0
.在第一个compareTo
返回0
的情况下,您可以通过对字符串本身执行compareTo
来做到这一点。
final result:最后结果:
loadedSummaryList.sort(
(a, b) {
int aIntex = sortList.indexOf(a);
int bIntex = sortList.indexOf(b);
if (aIntex == -1) aIntex = sortList.length;
if (bIntex == -1) bIntex = sortList.length;
var result = aIntex.compareTo(bIntex);
if (result != 0) {
return result;
} else {
return a.compareTo(b);
}
},
);
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