The char data type in Java represents a 16-bit Unicode character. To display any Unicode character, you need to use a font that contains the character. What operating system are you using? The font that Windows uses in the command prompt window does not contain the full set of Unicode characters. If you try to display a character which is not in the font, it will display a "?".
By the way, I looked up character 897 (code point U+0381) on the Unicode website, and this code point is empty - there is no character assigned to that particular code.