Java TreeSet tailSet() Method

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Description

The Java TreeSet tailSet(E fromElement) method is used to return a view of the portion of this set whose elements are greater than or equal to fromElement.

Declaration

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

public SortedSet<E> tailSet(E fromElement)

Parameters

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

Return Value

The method call returns a view of the portion of this set whose elements are greater than or equal to fromElement.

Exception

• ClassCastException − This is thrown if fromElement is not compatible with this set's comparator (or, if the set has no comparator, if fromElement does not implement Comparable). Implementations may, but are not required to, throw this exception if fromElement cannot be compared to elements currently in the set.

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

• IllegalArgumentException − This is thrown if this set itself has a restricted range, and fromElement lies outside the bounds of the range

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

Description

The tailSet(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.tailSet() method.

public NavigableSet<E> tailSet(E fromElement, boolean inclusive)

Parameters

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

• inclusive − This is true if the low 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 are greater than or equal to fromElement.

Exception

• ClassCastException − This is thrown if fromElement is not compatible with this set's comparator (or, if the set has no comparator, if fromElement does not implement Comparable). Implementations may, but are not required to, throw this exception if fromElement cannot be compared to elements currently in the set.

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

• IllegalArgumentException − This is thrown if this set itself has a restricted range, and fromElement lies outside the bounds of the range

Getting tailSet of a TreeSet of Integer Example

The following example shows the usage of Java TreeSet tailSet(E fromElement) method to get a view of the portion of this set whose elements range from fromElement, inclusive. We've created two TreeSet objects of Integer. Then few entries are added using add() method and a tailSet 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>treetailSet = 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 tailSet
      treetailSet = (TreeSet)treeadd.tailSet(3); 

      System.out.println("Tree tailSet data: " + treetailSet);
	  
   }    
}

Output

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

Tree tailSet data: [3, 4, 5, 6, 7, 8]

Getting tailSet of a TreeSet of String Example

The following example shows the usage of Java TreeSet tailSet(E fromElement,boolean inclusive) method to get a view of the portion of this set whose elements range from fromElement (included as inclusive is true). We've created two TreeSet objects of Integer. Then few entries are added using add() method and a tailSet 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>treetailSet = 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 tailSet
      treetailSet = (TreeSet)treeadd.tailSet(3,true); 

      System.out.println("Tree tailSet data: " + treetailSet);	  
   }    
}

Output

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

Tree tailSet data: [3, 4, 5, 6, 7, 8]

Getting tailSet of a TreeSet of Object Example

The following example shows the usage of Java TreeSet tailSet(E fromElement,boolean inclusive) method to get a view of the portion of this set whose elements range from fromElement (excluded as fromInclusive is false). We've created two TreeSet objects of Integer. Then few entries are added using add() method and a tailSet 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>treetailSet = 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 tailSet
      treetailSet = (TreeSet)treeadd.tailSet(3,false); 

      System.out.println("Tree tailSet data: " + treetailSet);	  
   }    
}

Output

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

Tree tailSet data: [4, 5, 6, 7, 8]