treemap in java code example

Example 1: list in java

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;
public class Main {
   public static void main(String[] args) {
      List<String> list = new ArrayList<String>();
      list.add("a");
      list.add("b");
      list.add("c");
      list.add("d");
      list.add("e");
      list.add("f");
      
      //On met la liste dans le désordre
      Collections.shuffle(list);
      System.out.println(list);
      
      //On la remet dans l'ordre
      Collections.sort(list);
      System.out.println(list);
      
      Collections.rotate(list, -1);
      System.out.println(list);
      
      //On récupère une sous-liste
      List<String> sub = list.subList(2, 5);
      System.out.println(sub);
      Collections.reverse(sub);
      System.out.println(sub);
      
      //On récupère un ListIterator
      ListIterator<String> it = list.listIterator();
      while(it.hasNext()){
         String str = it.next();
         if(str.equals("d"))
            it.set("z");
      }
      while(it.hasPrevious())
         System.out.print(it.previous());
      
   }
}

Example 2: TreeMap in java

import java.util.Map;
import java.util.TreeMap;
public class TreeMapExample
{
   public static void main(String[] args) 
   {
      TreeMap<Integer, String> tm = new TreeMap<Integer, String>();    
      tm.put(1000, "Apple");    
      tm.put(1002, "Raspberry");    
      tm.put(1001, "Velvet apple");    
      tm.put(1003, "Banana");    
      for(Map.Entry obj : tm.entrySet())
      {    
         System.out.println(obj.getKey() + " " + obj.getValue());    
      }
   }
}

Example 3: java treemap

import java.util.*;

// Declare the variable using the interface of the object for flexibility.
// Non-primative data types only.
Map<Integer, String> mambo = new TreeMap<Integer, String>();

mambo.put(key, value);
// TreeMap will be sorted by key.
// Work with any comparable object as a key.

mambo.put(1, "Monica");
mambo.put(2, "Erica");
mambo.put(3, "Rita");

Example 4: treemap in java

TreeSet: Can contain only unique values and it is sorted in ascending order
TreeMap: Can contain only unique keys and keys are sorted in ascending order.

Example 5: what is treemap

- TreeMap doesn't have null key and keys are sorted
 Can contain only unique keys and keys are sorted in ascending order.