Java TreeMap size() Method

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Description

The Java TreeMap size() method is used to return the number of key-value mappings in this map.

Declaration

Following is the declaration for java.util.TreeMap.size() method.

 public int size() 

Parameters

NA

Return Value

The method call returns the number of key-value mappings in this map.

Exception

NA

Getting Size of a TreeMap of Integer,Integer Pair Example

The following example shows the usage of Java TreeMap size() method to get the total key-value mappings present in the map. We've created a TreeMap object of Integer,Integer pairs. Then few entries are added, and using size() we're printing a count of key-value mappings.

 package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Integer> treemap = new TreeMap<>(); // populating tree map treemap.put(2, 2); treemap.put(1, 1); treemap.put(3, 3); treemap.put(6, 6); treemap.put(5, 5); // getting size of the map System.out.println("Size of the map: "+treemap.size()); } } 

Output

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

 Size of the map: 5 

Getting Size of a TreeMap of Integer,String Pair Example

The following example shows the usage of Java TreeMap size() method to get the total key-value mappings present in the map. We've created a TreeMap object of Integer,String pairs. Then few entries are added, and using size() we're printing a count of key-value mappings.

 package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, String> treemap = new TreeMap<>(); // populating tree map treemap.put(2, "two"); treemap.put(1, "one"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(5, "five"); // getting size of the map System.out.println("Size of the map: "+treemap.size()); } } 

Output

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

 Size of the map: 5 

Getting Size of a TreeMap of Integer,Object Pair Example

The following example shows the usage of Java TreeMap size() method to get the total key-value mappings present in the map. We've created a TreeMap object of Integer,Student pairs. Then few entries are added, and using size() we're printing a count of key-value mappings.

 package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Student> treemap = new TreeMap<>(); // populating tree map treemap.put(2, new Student(2, "Robert")); treemap.put(1, new Student(1, "Julie")); treemap.put(3, new Student(3, "Adam")); treemap.put(6, new Student(6, "Julia")); treemap.put(5, new Student(5, "Tom")); // getting size of the map System.out.println("Size of the map: "+treemap.size()); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { if(obj == null) return false; Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } } 

Output

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

 Size of the map: 5