Question

I would like write a java function like:
if one char is not in GB2312, return false

Boolean isGB2312(String chinese) {
    ......
}

Answer 1

import java.nio.charset.*;

class Some{

public static void main(String args[]) 
 {
final Charset cs = Charset.forName("GB2312");
final CharsetEncoder encode = cs.newEncoder();
System.out.println(encode.canEncode("ダチヂッツヅテデ")); 
 }

}

UPDATE:
As a static method:

final static boolean isGB2312(final String s)
{
return java.nio.charset.Charset.forName("GB2312").newEncoder().canEncode(s);
}