Java TreeSet subSet() Method

Description

The Java TreeSet subSet(E fromElement,E toElement) method is used to return a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive.

Declaration

Following is the declaration for java.util.TreeSet.subSet() method.

public SortedSet<E> subSet(E fromElement,E toElement)

Parameters

  • fromElement − This is the low endpoint (inclusive) of the returned set.

  • toElement − This is the high endpoint (exclusive) of the returned set.

Return Value

The method call returns a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive.

Exception

  • ClassCastException − This is thrown if fromElement and toElement cannot be compared to one another using this set's comparator.

  • NullPointerException − This is thrown if fromElement or toElement is null and this set uses natural ordering, or its comparator does not permit null elements.

  • IllegalArgumentException − This is thrown if fromElement is greater than toElement; or if this set itself has a restricted range, and fromElement or toElement lies outside the bounds of the range.

Java TreeSet subSet(E fromElement,boolean fromInclusive,E toElement,boolean toInclusive) Method

Description

The subSet(E fromElement,boolean fromInclusive,E toElement,boolean toInclusive) method is used to return a view of the portion of this set whose elements range from fromElement to toElement. If fromElement and toElement are equal, the returned set is empty unless fromExclusive and toExclusive are both true.

Declaration

Following is the declaration for java.util.TreeSet.subSet() method.

public NavigableSet<E> subSet(E fromElement,boolean fromInclusive,E toElement,boolean toInclusive)

Parameters

  • fromElement − This is the low endpoint of the returned set.

  • fromInclusive − This is true if the low endpoint is to be included in the returned view.

  • toElement − This is the high endpoint of the returned set.

  • toInclusive − This is true if the high endpoint is to be included in the returned view.

Return Value

The method call returns a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive.

Exception

  • ClassCastException − This is thrown if fromElement and toElement cannot be compared to one another using this set's comparator.

  • NullPointerException − This is thrown if fromElement or toElement is null and this set uses natural ordering, or its comparator does not permit null elements.

  • IllegalArgumentException − This is thrown if fromElement is greater than toElement; or if this set itself has a restricted range, and fromElement or toElement lies outside the bounds of the range.

Getting SubSet of a TreeSet of Integer Example

The following example shows the usage of Java TreeSet subset(E fromElement,E toElement) method to get a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive. We've created two TreeSet objects of Integer. Then few entries are added using add() method and a subset retrieved from first treeset and printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet <Integer>treeadd = new TreeSet<>();
      TreeSet <Integer>treesubset = new TreeSet<>();

      // adding in the tree set
      treeadd.add(1);
      treeadd.add(2);
      treeadd.add(3);
      treeadd.add(4);
      treeadd.add(5);
      treeadd.add(6);
      treeadd.add(7);
      treeadd.add(8);

      // creating subset
      treesubset = (TreeSet)treeadd.subSet(3,7); 

      System.out.println("Tree subset data: " + treesubset);
	  
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Tree subset data: [3, 4, 5, 6]

Getting SubSet of a TreeSet of String Example

The following example shows the usage of Java TreeSet subset(E fromElement,boolean fromInclusive,E toElement,boolean toInclusive) method to get a view of the portion of this set whose elements range from fromElement (included as fromInclusive is true), to toElement (included as toInclusive is true). We've created two TreeSet objects of Integer. Then few entries are added using add() method and a subset retrieved from first treeset and printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet <Integer>treeadd = new TreeSet<>();
      TreeSet <Integer>treesubset = new TreeSet<>();

      // adding in the tree set
      treeadd.add(1);
      treeadd.add(2);
      treeadd.add(3);
      treeadd.add(4);
      treeadd.add(5);
      treeadd.add(6);
      treeadd.add(7);
      treeadd.add(8);

      // creating subset
      treesubset = (TreeSet)treeadd.subSet(3,true, 7, true); 

      System.out.println("Tree subset data: " + treesubset);	  
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Tree subset data: [3, 4, 5, 6, 7]

Getting SubSet of a TreeSet of Object Example

The following example shows the usage of Java TreeSet subset(E fromElement,boolean fromInclusive,E toElement,boolean toInclusive) method to get a view of the portion of this set whose elements range from fromElement (excluded as fromInclusive is false), to toElement (excluded as toInclusive is true). We've created two TreeSet objects of Integer. Then few entries are added using add() method and a subset retrieved from first treeset and printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet <Integer>treeadd = new TreeSet<>();
      TreeSet <Integer>treesubset = new TreeSet<>();

      // adding in the tree set
      treeadd.add(1);
      treeadd.add(2);
      treeadd.add(3);
      treeadd.add(4);
      treeadd.add(5);
      treeadd.add(6);
      treeadd.add(7);
      treeadd.add(8);

      // creating subset
      treesubset = (TreeSet)treeadd.subSet(3,false, 7, false); 

      System.out.println("Tree subset data: " + treesubset);	  
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Tree subset data: [4, 5, 6]
java_util_treeset.htm
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