Casting String to Charsequence

Question

What is the purpose of casting String to CharSequence explicitly? String itself implements CharSequence interface.

Spring 4.x supports Java 6+ and CharSequence is present since 1.4.

Code snippet from Spring Framework:

public static boolean hasText(String str) {
    // Why do we cast str to CharSequence? 
    return hasText((CharSequence) str);
}

public static boolean hasText(CharSequence str) {
    if (!hasLength(str)) {
        return false;
    }

    int strLen = str.length();
    for (int i = 0; i < strLen; i++) {
        if (!Character.isWhitespace(str.charAt(i))) {
            return true;
        }
    }
    return false;
}

So that it won't recurse infinitely. The method could actually be removed. It is probably only there for backwards compatibility. — user207421, Jun 27 '17 at 07:58
@EJP, oh..so we do it to point compiler that we want to execute method specific to `CharSequence` parameter. Thank you. — Andrii Abramov, Jun 27 '17 at 07:59
@EJP this is the right answer. You should post it so that it can be accepted. — Arnaud Denoyelle, Jun 27 '17 at 08:04

score 5 · Accepted Answer · edited Jun 28 '17 at 21:00

5

So that it won't recurse infinitely. The method could actually be removed. It is probably only there for backwards compatibility.

edited Jun 28 '17 at 21:00

Andrii Abramov

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answered Jun 27 '17 at 08:06

user207421

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Casting String to Charsequence

1 Answers1