Trimming whitespace from strings

🔹 1️⃣ String.trim()

The classic method for removing whitespace from both ends of a string.

Syntax:

String trimmed = str.trim();

String trimmed = str.trim();

Behavior:

• Removes leading and trailing whitespace.
• Whitespace includes:
  spaces (' '), tabs ('\t'), newlines ('\n'), carriage returns ('\r').

✅ Example:

String s = "   Hello World!  ";
System.out.println(s.trim());

String s = "   Hello World!  ";
System.out.println(s.trim());

Output:

Hello World!

Hello World!

🔹 2️⃣ Limitation of trim()

trim() only removes characters ≤ ‘\u0020’ (space).
It does not handle all Unicode whitespace characters (like non-breaking spaces).

Example:

String s = "\u00A0Hello\u00A0"; // non-breaking spaces
System.out.println(s.trim().equals("Hello")); // false

String s = "\u00A0Hello\u00A0"; // non-breaking spaces
System.out.println(s.trim().equals("Hello")); // false

🔹 3️⃣ String.strip() — Modern Alternative (Java 11+)

Introduced in Java 11, strip() is Unicode-aware and replaces trim() for most modern uses.

Syntax:

String result = str.strip();

String result = str.strip();

Behavior:

• Removes all Unicode whitespace (not just ASCII).
• Uses Character.isWhitespace() to decide what counts as whitespace.

✅ Example:

String s = "\u2003 Hello World! \u2003"; // contains em space
System.out.println(s.strip());

String s = "\u2003 Hello World! \u2003"; // contains em space
System.out.println(s.strip());

Output:

Hello World!

Hello World!

🔹 4️⃣ Related Methods (Java 11+)

🔹 5️⃣ Comparison Table

🔹 6️⃣ Example Comparison

String s = "\u2002Java\u2002"; // contains en-space (U+2002)

System.out.println("[" + s.trim() + "]");  // [ Java ]
System.out.println("[" + s.strip() + "]"); // [Java]

String s = "\u2002Java\u2002"; // contains en-space (U+2002)

System.out.println("[" + s.trim() + "]");  // [ Java ]
System.out.println("[" + s.strip() + "]"); // [Java]

✅ strip() works correctly with all Unicode whitespaces.

🔹 7️⃣ Summary

💡 Best practice:

Always use strip() in modern Java (11+) unless you specifically need the old trim() behavior.