Integer Object (Unicode) to Characterobject

Question

:)I am pretty new to coding! My question is as following:

I have a method which gets a Integer Object i as a parameter and this Integer is supposed to be a Unicode. Now my question is, is there a way to transform a given Unicode to a Characterobject? A little example to illustrate the question:

public Character randomName(Integer i) {
    if(i == 0)
            throw new NullPointerException();
    if(i > Character.MAX_VALUE)
            throw new FormatException(i);
    else {
            Character c = new Character(i);
            return c;
}

of course this doesn't work but i can't find a way around it.... Downcasting didnt work and I usually use char and int but in this case i have to do it that way.

Thanks for the help already!!

Does this answer your question? [Creating Unicode character from its number](https://stackoverflow.com/questions/5585919/creating-unicode-character-from-its-number) — Tarmo, Feb 01 '22 at 11:49
It certainly helped, still, as the return type is a single Character Object I still dont know how to turn the integer into a Character but thanks a lot, it helped already a little! — Serkan Besim, Feb 01 '22 at 11:55
Note that a Character/char can't hold all possible Unicode codepoints. — Shawn, Feb 01 '22 at 12:06
But if that's not a problem, `return Character.vakueOf((char) i.intValue());` — Shawn, Feb 01 '22 at 12:08

Stephen C · Accepted Answer · 2022-02-01T23:44:26.590

The problem is that a Character object represents a char; i.e. a number on the range 0 through 0xffff. Unicode code-points range up to U+10FFFF and many cannot be represented as a single char value.

So this gives you a problem:

If the code-points that you want to represent are all between U+0000 and U+FFFF, then you can represent them as Character values.
If any are U+10000 or larger, then it won't work.

So, if you have an int that represents a Unicode code-point, you need to do do something like this:

int value = ...

if (Character.isDefined(value)) {
    if (value <= 0xffff) {
        return Character.valueOf((char) value);
    } else {
        // code point not representable as a `Character`
    }
} else {
    // Not a valid code-point at all
}

Note:

int values that are not valid code points include negative values, values greater than 0x10ffff and lower and upper surrogate code-units.
A number of commonly used Unicode code-points are great than U+10000. For example, the code-points for Emojis! This means that using Character is a bad idea. It would be better to use either a String, a char[] or an Integer.

It seems to work so far.

I guess you haven't tried @Shawn's approach with an Emoji yet.

Is there a way around using a downcast?

No.

if(i == 0)
       throw new NullPointerException();

That is just wrong:

Zero is a valid code-point.
Even if it wasn't valid, it is NOT a null. So throwing NullPointerException is totally inappropriate.
If you are concerned about the case where i is null, don't worry. Any operation that unboxes i will automatically throw NullPointerException if it is null. Just let it happen ...

Wow, thanks! Well, my method is supposed to throw exceptions if the value is e.g negative or out of the Character's Max Value. So, it only turns the integer into a char after it checked if it is even possible. Yes a String would also be a lot easier but my task clearly wants a Charakter..... Thanks a lot!!! — Serkan Besim, Feb 01 '22 at 13:59
Sounds like your task is incorrect! But I guess there are few people who teach Java and don't understand Unicode properly. — Stephen C, Feb 01 '22 at 14:03

Integer Object (Unicode) to Characterobject

1 Answers1