Fixed API and added plain-text USD↔INR converter with user input

Author: Ilmakram

src/main/java/com/thealgorithms/conversions/USDtoIND.java

@@ -0,0 +1,89 @@
+package com.thealgorithms.conversions;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.Scanner;
+
+public class USDtoIND {
+
+    // ✅ Free, keyless API endpoint
+    private static final String API_URL = "https://open.er-api.com/v6/latest/USD";
+
+    /**
+     * Fetches the live USD to INR rate from open.er-api.com
+     * 
+     * @return the exchange rate, or -1 if an error occurs
+     */
+    public static double fetchLiveRate() {
+        try {
+            // Step 1: Connect to the URL
+            URL url = new URL(API_URL);
+            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+            conn.setRequestMethod("GET");
+
+            // Step 2: Read API response
+            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
+            StringBuilder response = new StringBuilder();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                response.append(line);
+            }
+            reader.close();
+
+            // Step 3: Extract INR value manually from the JSON text
+            String json = response.toString();
+
+            // Find INR rate
+            int start = json.indexOf("\"INR\":") + 6;
+            int end = json.indexOf(",", start);
+            if (end == -1)
+                end = json.indexOf("}", start);
+            String rateStr = json.substring(start, end);
+
+            return Double.parseDouble(rateStr);
+        } catch (Exception e) {
+            System.out.println("Error fetching exchange rate: " + e.getMessage());
+            return -1;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("USD ↔ INR Converter");
+        System.out.println("--------------------");
+        System.out.println("Choose conversion type:");
+        System.out.println("1. USD → INR");
+        System.out.println("2. INR → USD");
+        System.out.print("Enter your choice (1 or 2): ");
+        int choice = sc.nextInt();
+
+        // Fetch live exchange rate
+        double rate = fetchLiveRate();
+
+        if (rate <= 0) {
+            System.out.println("Failed to retrieve live exchange rate. Please check your internet connection.");
+            sc.close();
+            return;
+        }
+
+        // Conversion logic
+        if (choice == 1) {
+            System.out.print("Enter amount in USD: ");
+            double usd = sc.nextDouble();
+            double inr = usd * rate;
+            System.out.printf("%.2f USD = %.2f INR (Rate: %.2f)%n", usd, inr, rate);
+        } else if (choice == 2) {
+            System.out.print("Enter amount in INR: ");
+            double inr = sc.nextDouble();
+            double usd = inr / rate;
+            System.out.printf("%.2f INR = %.2f USD (Rate: %.2f)%n", inr, usd, rate);
+        } else {
+            System.out.println("Invalid choice. Please run the program again and select 1 or 2.");
+        }
+
+        sc.close();
+    }
+}