为什么 parseBoolean 不抛出异常？

Question

Considering

boolean b = Boolean.parseBoolean("100");

I thought it would throw an exception because "100" is neither "true" nor "false" . But it passed, no exceptions.

Why does the method not throw?

Answer 1

Reading the JavaDoc of the method (emphasis mine):

Parses the string argument as a boolean. The boolean returned represents the value true if the string argument is not null and is equal, ignoring case, to the string "true" . Otherwise, a false value is returned , including for a null argument.

Looking at the implementation :

    public static boolean parseBoolean(String s) {
        return "true".equalsIgnoreCase(s);
    }

So anything not equal to the String "true" – ignoring case – is considered to be false