How to URL Decode a String in Java

Introduction

URL decoding is a vital task in Java when you need to safely extract data from a URL. It ensures that encoded characters in the URL are correctly represented and can be converted back to their original form. In Java, you can perform URL decoding using the URLDecoder class from the java.net package.

Code and Explanation

Here's how to URL decode a string in Java:

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;

public class URLDecodingExample {
    public static void main(String[] args) {
        try {
            // Encoded URL string
            String encodedString = "Hello%2C+World%21";
            
            // URL decode the string
            String decodedString = URLDecoder.decode(encodedString, "UTF-8");
            
            // Print the decoded string
            System.out.println("Decoded Text: " + decodedString);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }
}

Explanation:

1. Import the necessary classes:

   • java.io.UnsupportedEncodingException for handling decoding errors.
   • java.net.URLDecoder for decoding the URL-encoded string.

2. Create a main method for your Java program.

3. Define the encoded URL string from which you want to extract data.

4. Use URLDecoder.decode() to decode the encoded URL string. The second parameter, "UTF-8", specifies the character encoding scheme used during encoding (UTF-8 is a common choice).

5. Print the decoded string to the console.

This code illustrates how to perform URL decoding in Java, ensuring that the encoded URL string is correctly converted back to its original form, allowing you to extract meaningful data from it.