| 9. 21. 21. headset, tailset and subset |
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headSet: The fromElement will be in the subset, while the toElement will not: fromElement
<= set view < toElement |
If you want the toElement to be in the subset, you must pass in the next node of the tree, or
a value that is just beyond the element. |
If you are using string nodes, you can adding something to the end: |
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SortedSet headSet = set.headSet(toElement+"\0");
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To remove the fromElement in the subset: |
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SortedSet tailSet = set.tailSet(fromElement+"\0");
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To get a set that includes both ends, use: |
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SortedSet bothEnds = set.subSet(fromElement, toElement+"\0");
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Or, for a set that includes neither end, use: |
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SortedSet neitherEnd = set.subSet(fromElement+"\0", toElement);
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import java.util.Arrays;
import java.util.TreeSet;
public class MainClass {
public static void main(String args[]) throws Exception {
String elements[] = { "A", "C", "D", "G", "F" };
TreeSet set = new TreeSet(Arrays.asList(elements));
System.out.println(set.tailSet("C"));
System.out.println(set.headSet("C"));
System.out.println(set.headSet("C\0"));
System.out.println(set.tailSet("C\0"));
System.out.println(set.subSet("C", "F\0"));
System.out.println(set.subSet("C", "C\0"));
System.out.println(set.subSet("C", "C"));
}
}
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[C, D, F, G]
[A]
[A, C]
[D, F, G]
[C, D, F]
[C]
[] |
While displaying elements in an easily sorted manner is nice, if you don't need the behavior,
the cost to add elements and search for them is not worth it. |