Invisible characters in Java Strings

Question

String a = "Hello\u200e";
String b = "Hello\u200f";

System.out.println("a = '" + a + "' and b = '" + b + "' are length "
                     + a.length() + " and " + b.length()
                     + ", equals() is " + a.equals(b));

The code in the above code snippet produces the following output.

a = 'Hello‎' and b = 'Hello‏' are length 6 and 6, equals() is false

Although the value of both a and b displayed on the console is Hello‏, a.equals(b) returns false. How?

Answer 1

U+200E and U+200F are not printable characters. They're both control characters which dictate how the text should be rendered - either left to right, or right to left.

You won't see these in the terminal, and they shouldn't be equivalent strings.

^{0x200E ^ 0x200F != 0}