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How to Unescape HTML in Java

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🏆 Unescaping HTML in Java: Because Code Deserves to Breathe​

Ever looked at <java>public static void main(String[] args) { ... }</java> and thought, "Wow, that’s an ancient spell!"? Well, fear not, brave developer! Today, we shall unmask these cryptic symbols and return them to their former glory! 💪🔥

1️⃣ The Magic of StringEscapeUtils.unescapeHtml4() 🪄​

Apache Commons Text brings us a powerful tool to unescape HTML like a pro! But first, let's summon it with Maven:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-text</artifactId>
    <version>1.10.0</version>
</dependency>

🔥 The Spell: unescapeHtml4()​

  • Takes an escaped HTML string and restores it to its true form.
  • If you pass null, it gracefully returns null (because it’s polite!).
  • Recognizes all standard HTML 4.0 entities.
  • If it encounters an unknown entity, it shrugs and leaves it alone. 😎

🏗 Example​

String escapedString = "&lt;java&gt;public static void main(String[] args) { ... }&lt;/java&gt;";
     
String unEscapedHTML = StringEscapeUtils.unescapeHtml4(escapedString);

System.out.println(unEscapedHTML);

🎉 Output:

<java>public static void main(String[] args) { ... }</java>

Ahhh, that’s better! Now our Java code can breathe! 😌

2️⃣ Rolling Our Own Unescaper (a.k.a. Doing It the Hard Way 🤓)​

Want to impress your teammates by reinventing the wheel? Here’s how you can build your own unescaper with plain Java!

🏗 The DIY Approach​

private static HashMap<String, String> htmlEntities;

static {
    htmlEntities = new HashMap<>();
    htmlEntities.put("&lt;", "<");
    htmlEntities.put("&gt;", ">");
    htmlEntities.put("&amp;", "&");
    htmlEntities.put("&quot;", "\"");
    htmlEntities.put("&nbsp;", " ");
    htmlEntities.put("&copy;", "\u00a9");
    htmlEntities.put("&reg;", "\u00ae");
    htmlEntities.put("&euro;", "\u20a0");
}

public static final String unescapeHTML(String source) {
    int i, j;
    boolean continueLoop;
    int skip = 0;
    
    do {
        continueLoop = false;
        i = source.indexOf("&", skip);
        if (i > -1) {
            j = source.indexOf(";", i);
            if (j > i) {
                String entityToLookFor = source.substring(i, j + 1);
                String value = htmlEntities.get(entityToLookFor);
                if (value != null) {
                    source = source.substring(0, i) + value + source.substring(j + 1);
                    continueLoop = true;
                } else {
                    skip = i + 1;
                    continueLoop = true;
                }
            }
        }
    } while (continueLoop);
    return source;
}

🏗 Example Usage​

String input = "&lt;java&gt;public static void main(String[] args) { ... }&lt;/java&gt;";
     
String output = unescapeHTML(input);

System.out.println(output);

🎉 Output:

<java>public static void main(String[] args) { ... }</java>

🎯 The Takeaway​

  • Use Apache Commons if you value your time. ⏳
  • Build your own if you enjoy a bit of coding adventure. 🏗
  • Either way, you now have the power to unleash your HTML-escaped text into its readable form! 🚀

Happy Coding! 🎉🎨