Java 中的 TreeSet subSet()方法
原文:https://www . geesforgeks . org/treeset-subset-method-in-Java/
java.util.TreeSet.subSet()用于返回参数中提到的范围内现有 TreeSet 的子集。该方法接受一个上限和一个下限，并返回该范围内提到的所有元素。如果元素存在于集合中，则包括下限，而排除上限。基本上，它取大于等于下限且严格小于上限的子集。
语法:
*TreeSet* tree_set.subSet(Object low_element, Object up_element)
参数:
- low_element: 这是 TreeSet 的类型，定义了评估子集的下限或起始元素。该元素包含在子集中。
- up_element: 这是 TreeSet 的类型，定义了子集评估的上限或最后一个元素。此元素被排除在子集之外。
返回值:该方法返回给定参数范围内提到的 TreeSet 类型的子集。
下面的程序说明了 Java . util . TreeSet . SubIt()方法:
程序 1 :
// Java code to illustrate subSet() method
import java.io.*;
import java.util.Iterator;
import java.util.TreeSet;
public class Tree_Set_Demo {
public static void main(String[] args)
{
// Creating an empty TreeSet
TreeSet<Integer> tree_set = new TreeSet<Integer>();
// Adding the elements using add()
tree_set.add(5);
tree_set.add(1);
tree_set.add(50);
tree_set.add(10);
tree_set.add(20);
tree_set.add(6);
tree_set.add(20);
tree_set.add(18);
tree_set.add(9);
tree_set.add(30);
// Creating the subset tree
TreeSet<Integer> sub_set = new TreeSet<Integer>();
// Limiting the values till 5
sub_set = (TreeSet<Integer>)tree_set.subSet(6, 30);
// Creating an Iterator
Iterator iterate;
iterate = sub_set.iterator();
// Displaying the tree set data
System.out.println("The resultant values within the sub set: ");
// Iterating through the subset
while (iterate.hasNext()) {
System.out.println(iterate.next() + " ");
}
}
}
Output:
The resultant values within the sub set:
6
9
10
18
20
程序 2 :
// Java code to illustrate subSet() method when TreeSet
// contains elements of String type
import java.io.*;
import java.util.Iterator;
import java.util.TreeSet;
public class Tree_Set_Demo {
public static void main(String[] args)
{
// Creating an empty TreeSet
TreeSet<String> tree_set = new TreeSet<String>();
// Adding the elements using add()
tree_set.add("Welcome");
tree_set.add("To");
tree_set.add("Geek");
tree_set.add("4");
tree_set.add("Geeks");
tree_set.add("TreeSet");
// Creating the subset tree
TreeSet<String> sub_set = new TreeSet<String>();
// Limiting the values till 5
sub_set = (TreeSet<String>)tree_set.subSet("4", "TreeSet");
// Creating an Iterator
Iterator iterate;
iterate = sub_set.iterator();
// Displaying the tree set data
System.out.println("The resultant values within the sub set: ");
// Iterating through the subset
while (iterate.hasNext()) {
System.out.println(iterate.next() + " ");
}
}
}
Output:
The resultant values within the sub set:
4
Geek
Geeks
To
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