020-004-002

Map Basics: Key-Value Pair Management

Medium

Problem Description

In this problem, you will create a program that registers and retrieves key-value pairs using HashMap<String, Integer>, checks key existence, and displays the result to standard output.

HashMap Basics

HashMap is a class that manages key-value pairs.

Basic Operations

HashMap<String, Integer> map = new HashMap<>();
map.put("apple", 100);  // Add key-value pair
map.get("apple");       // Get value by key
map.containsKey("apple"); // Check key existence

Learning Points

  • Keys must be unique, values can be duplicated
  • get() returns null for non-existent keys
  • Use containsKey() to check existence beforehand

Test Cases

※ Output examples follow programming industry standards

Normal case
Input:
3
apple 150
banana 100
orange 200
apple
Expected Output:
150
Normal case
Input:
2
book 500
pen 80
pen
Expected Output:
80

Your Solution

Current Mode:● My Code
import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Write your code here

sc.close();
}
}
0 B / 5 MB

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