Java中的TreeSet subSet()方法

爪哇。util。TreeSet。subSet()用于返回参数中提到的范围内现有树集的子集。该方法接受上限和下限,并返回范围内提到的所有元素。如果元素存在于集合中,则包含下限,但不包括上限。基本上,它取大于等于下限且严格小于上限的子集。

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语法:

TreeSet tree_set.subSet(Object low_element, Object up_element)

参数:

  • 低_元素: 这是树集的类型,定义下限或从中计算子集的起始元素。此元素包含在子集中。
  • up_元素: 这是树集的类型,定义了子集计算的上限或最后一个元素。此元素将从子集中排除。

返回值: 该方法返回给定参数范围内提到的树集类型的子集。

下面的程序演示了java。util。TreeSet。subSet()方法:

方案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() + " " );
}
}
}


输出:

The resultant values within the sub set: 
6 
9 
10 
18 
20

方案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() + " " );
}
}
}


输出:

The resultant values within the sub set: 
4 
Geek 
Geeks 
To

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