Java TreeMap get() Method

The TreeMap.get() method in Java is used to retrieve the value associated with a specific key from the map. This guide will cover the method’s usage, explain how it works, and provide examples to demonstrate its functionality. We will also cover a real-world use case to show how TreeMap.get() can be used effectively.

Table of Contents

1. Introduction
2. get Method Syntax
3. Examples
   • Retrieving a Value from a TreeMap
   • Handling Non-Existent Keys
4. Real-World Use Case
   • Example: Retrieving Student Scores
5. Conclusion

Introduction

The TreeMap.get() method is a member of the TreeMap class in Java. It allows you to retrieve the value associated with a specific key from the map. If the key is not present in the map, the method returns null.

get() Method Syntax

The syntax for the get method is as follows:

public V get(Object key)

• Parameters:
  • key: The key whose associated value is to be returned.
• Returns: The value associated with the specified key, or null if the map contains no mapping for the key.

Examples

Retrieving a Value from a TreeMap

The get method can be used to retrieve the value associated with a specific key from the TreeMap.

Example

import java.util.TreeMap;

public class GetExample {
    public static void main(String[] args) {
        // Creating a TreeMap with String keys and Integer values
        TreeMap<String, Integer> treeMap = new TreeMap<>();

        // Adding entries to the TreeMap
        treeMap.put("Ravi", 25);
        treeMap.put("Priya", 30);
        treeMap.put("Vijay", 35);
        treeMap.put("Anita", 28);
        treeMap.put("Suresh", 40);

        // Retrieving the value associated with the key "Priya"
        Integer age = treeMap.get("Priya");

        // Printing the retrieved value
        System.out.println("Age of Priya: " + age);
    }
}

Output:

Age of Priya: 30

Handling Non-Existent Keys

If the key is not present in the TreeMap, the get method returns null.

Example

import java.util.TreeMap;

public class NonExistentKeyExample {
    public static void main(String[] args) {
        // Creating a TreeMap with String keys and Integer values
        TreeMap<String, Integer> treeMap = new TreeMap<>();

        // Adding entries to the TreeMap
        treeMap.put("Ravi", 25);
        treeMap.put("Priya", 30);
        treeMap.put("Vijay", 35);
        treeMap.put("Anita", 28);
        treeMap.put("Suresh", 40);

        // Attempting to retrieve the value associated with the key "Amit"
        Integer age = treeMap.get("Amit");

        // Printing the result
        System.out.println("Age of Amit: " + age);
    }
}

Output:

Age of Amit: null

Real-World Use Case

Example: Retrieving Student Scores

A common real-world use case for TreeMap.get() is managing a student score database where you need to retrieve the score of a specific student.

Example

import java.util.TreeMap;

public class StudentScores {
    public static void main(String[] args) {
        // Creating a TreeMap to manage student names and their scores
        TreeMap<String, Integer> studentScores = new TreeMap<>();

        // Adding student names and their scores to the TreeMap
        studentScores.put("Ravi", 85);
        studentScores.put("Priya", 90);
        studentScores.put("Vijay", 75);
        studentScores.put("Anita", 95);
        studentScores.put("Suresh", 80);

        // Retrieving the score of a specific student
        Integer score = studentScores.get("Priya");

        // Printing the student's score
        System.out.println("Score of Priya: " + score);
    }
}

Output:

Score of Priya: 90

In this example, TreeMap.get() is used to retrieve the score of a specific student from the map, making it easy to manage and access student scores.

Conclusion

The TreeMap.get() method in Java provides a way to retrieve the value associated with a specific key from the map. By understanding how to use this method, you can efficiently manage and navigate collections of key-value pairs in your Java applications. The method allows you to access values based on their keys, making it a versatile tool for data management in various scenarios.