Java/Collections Data Structure/TreeSet

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Add values to TreeSet<String>

   <source lang="java">
  

import java.util.TreeSet; class TreeSetDemo {

 public static void main(String args[]) {
   TreeSet<String> ts = new TreeSet<String>();
   ts.add("C");
   ts.add("A");
   ts.add("B");
   ts.add("E");
   ts.add("F");
   ts.add("D");
   System.out.println(ts);
 }

}


 </source>
   
  
 
  



Check if a particular value exists in Java TreeSet example

   <source lang="java">
 

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<String> tSet = new TreeSet<String>();
   tSet.add("1");
   tSet.add("2");
   tSet.add("3");
   tSet.add("4");
   tSet.add("5");
   boolean blnExists = tSet.contains("3");
   System.out.println("3 exists in TreeSet ? : " + blnExists);
 }

}


 </source>
   
  
 
  



Comparable with a sorted collection.

   <source lang="java">

import java.util.Set; import java.util.TreeSet; class Product implements Comparable<Product> {

 String prodName;
 int prodID;
 Product(String str, int id) {
   prodName = str;
   prodID = id;
 }
 public int compareTo(Product p2) {
   return prodName.rupareToIgnoreCase(p2.prodName);
 }
 public boolean equals(Object p2) {
   return prodName.rupareToIgnoreCase(((Product) p2).prodName) == 0;
 }

} public class Main {

 public static void main(String args[]) {
   Set<Product> prodList = new TreeSet<Product>();
   prodList.add(new Product("A", 13546));
   prodList.add(new Product("B", 04762));
   prodList.add(new Product("C", 12221));
   prodList.add(new Product("D", 44387));
   for (Product p : prodList)
     System.out.printf("%-14s ID: %d\n", p.prodName, p.prodID);
 }

}

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Copy all elements of Java TreeSet to an Object Array Example

   <source lang="java">
 
      

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<Integer> tSet = new TreeSet<Integer>();
   tSet.add(new Integer("1"));
   tSet.add(new Integer("2"));
   tSet.add(new Integer("3"));
   Object[] objArray = tSet.toArray();
   for (Object obj: objArray){
     System.out.println(obj);
   }
 }

}


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Creating a Sorted Set

   <source lang="java">

import java.util.Arrays; import java.util.Iterator; import java.util.Set; import java.util.TreeSet; public class Main {

 public static void main(String[] argv) {
   // Create the sorted set
   Set<String> set = new TreeSet<String>();
   set.add("b");
   set.add("c");
   set.add("a");
   Iterator it = set.iterator();
   while (it.hasNext()) {
     Object element = it.next();
     System.out.println(element);
   }
   // Create an array containing the elements in a set
   String[] array = (String[]) set.toArray(new String[set.size()]);
   Arrays.toString(array);
 }

}

 </source>
   
  
 
  



Get Head Set from Java TreeSet example

   <source lang="java">
 

import java.util.SortedSet; import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<String> tSet = new TreeSet<String>();
   tSet.add("1");
   tSet.add("2");
   tSet.add("3");
   tSet.add("4");
   tSet.add("5");
   SortedSet sortedSet = tSet.headSet("3");
   System.out.println("Head Set Contains : " + sortedSet);
 }

}


 </source>
   
  
 
  



Get lowest and highest value stored in Java TreeSet

   <source lang="java">
 

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<String> tSet = new TreeSet<String>();
   tSet.add("1");
   tSet.add("2");
   tSet.add("3");
   tSet.add("4");
   tSet.add("5");
   System.out.println("Lowest value Stored in Java TreeSet is : " + tSet.first());
   System.out.println("Highest value Stored in Java TreeSet is : " + tSet.last());
 }

}


 </source>
   
  
 
  



Get Size of Java TreeSet

   <source lang="java">
 

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<Integer> tSet = new TreeSet<Integer>();
   System.out.println("Size of TreeSet : " + tSet.size());
   tSet.add(new Integer("1"));
   tSet.add(new Integer("2"));
   tSet.add(new Integer("3"));
   System.out.println(tSet.size());
   // remove one element from TreeSet using remove method
   tSet.remove(new Integer("1"));
   System.out.println("Size of TreeSet after removal : " + tSet.size());
 }

}


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Get Sub Set from Java TreeSet

   <source lang="java">
 

import java.util.TreeSet; import java.util.SortedSet; public class Main {

 public static void main(String[] args) {
   TreeSet<String> tSet = new TreeSet<String>();
   tSet.add("1");
   tSet.add("2");
   tSet.add("3");
   tSet.add("4");
   tSet.add("5");
   
   SortedSet sortedSet = tSet.subSet("2", "5");
   System.out.println("SortedSet Contains : " + sortedSet);
 }

}


 </source>
   
  
 
  



Get Synchronized Set from Java TreeSet example

   <source lang="java">
 

import java.util.Collections; import java.util.Set; import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet treeSet = new TreeSet();
   Set set = Collections.synchronizedSet(treeSet);
 }

}


 </source>
   
  
 
  



Get Tail Set from Java TreeSet

   <source lang="java">
 

import java.util.SortedSet; import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<String> tSet = new TreeSet<String>();
   tSet.add("1");    
   tSet.add("2");
   tSet.add("3");
   tSet.add("5");
   tSet.add("4");
   SortedSet sortedSet = tSet.tailSet("2");
   System.out.println("Tail Set Contains : " + sortedSet);
 }

}


 </source>
   
  
 
  



Iterate through elements of Java TreeSet

   <source lang="java">
 

import java.util.Iterator; import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<Integer> tSet = new TreeSet<Integer>();
   tSet.add(new Integer("1"));
   tSet.add(new Integer("2"));
   tSet.add(new Integer("3"));
   Iterator itr = tSet.iterator();
   while (itr.hasNext()){
     System.out.println(itr.next());
   }
 }

}


 </source>
   
  
 
  



Loop and remove element from a TreeSet

   <source lang="java">
 

import java.util.Iterator; import java.util.Set; import java.util.TreeSet; public class TreeSetExample {

 public static void main(String[] args) {
   // Create a new TreeSet
   Set<Integer> set = new TreeSet<Integer>();
   // Add Items to the TreeSet
   set.add(new Integer(1));
   set.add(new Integer(2));
   set.add(new Integer(3));
   set.add(new Integer(4));
   set.add(new Integer(5));
   set.add(new Integer(6));
   set.add(new Integer(7));
   set.add(new Integer(8));
   set.add(new Integer(9));
   set.add(new Integer(10));
   // Use iterator to display the vsetes
   System.out.println("TreeSet Before: ");
   for (Iterator i = set.iterator(); i.hasNext();) {
     Integer integer = (Integer) i.next();
     System.out.println(integer);
   }
   // Remove the integer 6
   System.out.println("\nRemove Integer 6");
   set.remove(new Integer(6));
   // Use iterator to display the vsetes
   System.out.println("\nTreeSet After: ");
   for (Iterator i = set.iterator(); i.hasNext();) {
     Integer integer = (Integer) i.next();
     System.out.println(integer);
   }
 }

}


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Remove all elements from Java TreeSet

   <source lang="java">
 
      

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<Integer> tSet = new TreeSet<Integer>();
   tSet.add(new Integer("1"));
   tSet.add(new Integer("2"));
   tSet.add(new Integer("3"));
   System.out.println("TreeSet before removal : " + tSet);
   tSet.clear();
   System.out.println("TreeSet after removal : " + tSet);
   System.out.println("Is TreeSet empty ? " + tSet.isEmpty());
 }

}


 </source>
   
  
 
  



Remove specified element from Java TreeSet

   <source lang="java">
 

import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   TreeSet<Integer> tSet = new TreeSet<Integer>();
   tSet.add(new Integer("1"));
   tSet.add(new Integer("2"));
   tSet.add(new Integer("3"));
   System.out.println(tSet);
   System.out.println("Was 2 removed from TreeSet ? " + tSet.remove(new Integer("2")));
   System.out.println(tSet);
 }

}


 </source>
   
  
 
  



Sort items in a Set

   <source lang="java">
 

import java.util.Set; import java.util.TreeSet; public class Main {

 public static void main(String[] args) {
   Set<String> set = new TreeSet<String>();
   set.add("Z");
   set.add("A");
   set.add("F");
   set.add("B");
   set.add("H");
   set.add("X");
   set.add("N");
   for (String item : set) {
     System.out.print(item + " ");
   }
 }

}


 </source>
   
  
 
  



TreeSet, SortedSet and HashSet

   <source lang="java">
 

import java.util.HashSet; import java.util.Iterator; import java.util.Set; import java.util.SortedSet; import java.util.TreeSet; class SetDemo {

 public static void main(String[] args) {
   String[] letters = { "A", "B", "C", "D", "E" };
   Set s = new HashSet();
   for (int i = 0; i < letters.length; i++)
     s.add(letters[i]);
   if (!s.add(letters[0]))
     System.out.println("Cannot add a duplicate.\n");
   Iterator iter = s.iterator();
   while (iter.hasNext())
     System.out.println(iter.next());
   System.out.println("");
   SortedSet ss = new TreeSet();
   for (int i = 0; i < letters.length; i++)
     ss.add(letters[i]);
   if (!ss.add(letters[0]))
     System.out.println("Cannot add a duplicate.\n");
   iter = ss.iterator();
   while (iter.hasNext())
     System.out.println(iter.next());
 }

}


 </source>