Java Tutorial
TreeSet()
This constructor builds an empty TreeSet that will be sorted in ascending order based on natural order of elements.
TreeSet(Collection collection)
This constructor initializes the elements of the collection.
TreeSet(Comparator comparator)
This constructor builds an empty TreeSet that will be sorted based on comparator specified.
HashSet(SortedSet sortedSet)
Initializes TreeSet with SortedSet elements.
add method is used to add element in the TreeSet.
add(object)
contains method is used to check whether element exists in TreeSetor not. returns true if object exist in TreeSet, otherwise returns false.
contains(object)
remove method is used to remove element in the TreeSet.
remove(object)
size method is used to return the number of elements in the TreeSet.
size()
// Codingpointer Demonstrates TreeSet import java.util.*; class TreeSetTest { public static void main(String args[]) { TreeSet ts = new TreeSet(); //Add elements ts.add("B"); ts.add("E"); ts.add("D"); ts.add("E"); System.out.println(ts); } }Output:
$ java TreeSetTest [B, D, E]
import java.util.*; class TreeSetTest { public static void main(String args[]) { TreeSet ts = new TreeSet(); //Add elements ts.add("B"); ts.add("E"); ts.add("D"); ts.add("E"); System.out.println(ts); System.out.println("TreeSet contains 'B':" + ts.contains("B")); System.out.println("TreeSet contains 'R':" + ts.contains("R")); System.out.println("Size: "+ts.size()); ts.remove("E"); System.out.println("after removed 'E'"); System.out.println(ts); System.out.println("Size: "+ts.size()); } }Output:
java TreeSetTest [B, D, E] TreeSet contains 'B':true TreeSet contains 'R':false Size: 3 after removed 'E' [B, D] Size: 2
import java.util.*; class TreeSetTest { public static void main(String args[]) { TreeSet ts = new TreeSet(); //Add elements ts.add("B"); ts.add("E"); ts.add(2); ts.add("E"); System.out.println(ts); System.out.println("TreeSet contains 'B':" + ts.contains("B")); System.out.println("TreeSet contains 'R':" + ts.contains("R")); System.out.println("Size: "+ts.size()); ts.remove("E"); System.out.println("after removed 'E'"); System.out.println(ts); System.out.println("Size: "+ts.size()); } }Output:
$ java TreeSetTest Exception in thread "main" java.lang.ClassCastException: java.base/java.lang.String cannot be cast to java.base/java.lang.Integer at java.base/java.lang.Integer.compareTo(Unknown Source) at java.base/java.util.TreeMap.put(Unknown Source) at java.base/java.util.TreeSet.add(Unknown Source) at TreeSetTest.main(TreeSetTest.java:9)
Java Tutorial
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