fork(4) download
/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String str = "Americans said that Obama is ... Americans said that Barack Obama is ...";
    	Pattern ptrn = Pattern.compile("(?<!\\b[A-Z][a-z]{0,100}\\s)Obama(?!\\s+[A-Z][a-z]*)");
    	Matcher matcher = ptrn.matcher(str);
    	while (matcher.find()) {
    		System.out.println(matcher.group(0));
    	}
	}
}
Success #stdin #stdout 0.05s 4386816KB
stdin
Standard input is empty
stdout
Obama