英文:
Get the parent values in the arraylist from a list of decimal numbers
问题
我有一个包含以下数值的ArrayList（数值可能会变化）：
1
1.1
1.2
1.3
2
2.1
2.2
2.3
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
4
4.1
4.1.1
4.1.1.1
4.1.1.2
4.1.2
4.1.2.1
4.1.2.2
4.2
4.2.1
4.2.2
4.3
5
5.1
我需要在ArrayList中确定父级值，对于这种情况，ArrayList中的父级值如下：
1, 2, 3, 4, 4.1, 4.1.1, 4.1.2, 4.2, 5
例如，在此图片中，“父级值”（1、1.3）无法被选择，因为它们有子选项。
我在Android应用中有一个Spinner，并且我想要做类似的事情，即Spinner中只能隐藏或无法选择父级值。我不知道如何处理这个问题。
有任何想法吗？请提供帮助。
英文:
I have an arraylist with these values (the values can change):
1
1.1
1.2
1.3
2
2.1
2.2
2.3
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
4
4.1
4.1.1
4.1.1.1
4.1.1.2
4.1.2
4.1.2.1
4.1.2.2
4.2
4.2.1
4.2.2
4.3
5
5.1
I need to identifiy the fathers value in an arraylist, for this case, the arraylist has this fathers values:
1, 2, 3, 4, 4.1, 4.1.1, 4.1.2, 4.2, 5
for example, in this picture the "fathers values" (1, 1.3) can't be selected, because it has child options.
I have an spinner in an android app, and I want to do something like that, the idea is in the spinner only parent values are hidden or cannot be selected. I don't have idea how can I do with this exercise.
Any idea? Please
答案1
得分: 1
请尝试以下代码：
List<String> list = List.of(
"1", "1.1", "1.2", "1.3",
"2", "2.1", "2.2", "2.3",
"3", "3.1", "3.2", "3.3", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10",
"4", "4.1", "4.1.1", "4.1.1.1", "4.1.1.2", "4.1.2", "4.1.2.1", "4.1.2.2", "4.2", "4.2.1", "4.2.2", "4.3",
"5", "5.1");
Set<String> fathers = list.stream()
.map(e -> e.replaceAll("\\.\\d+$", ""))
.collect(Collectors.toCollection(LinkedHashSet::new));
System.out.println(fathers);
输出结果为：
[1, 2, 3, 4, 4.1, 4.1.1, 4.1.2, 4.2, 5]
英文:
Try this.
List<String> list = List.of(
"1", "1.1", "1.2", "1.3",
"2", "2.1", "2.2", "2.3",
"3", "3.1", "3.2", "3.3", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10",
"4", "4.1", "4.1.1", "4.1.1.1", "4.1.1.2", "4.1.2", "4.1.2.1", "4.1.2.2", "4.2", "4.2.1", "4.2.2", "4.3",
"5", "5.1");
Set<String> fathers = list.stream()
.map(e -> e.replaceAll("\\.\\d+$", ""))
.collect(Collectors.toCollection(LinkedHashSet::new));
System.out.println(fathers);
output
[1, 2, 3, 4, 4.1, 4.1.1, 4.1.2, 4.2, 5]
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