import java.util.*;
import java.util.regex.*;
import java.lang.*;
import java.io.*;
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String instanceResultString = "InstanceId: i-1234XYAadsadd, More text: InstanceId: u-222tttt, dde InstanceId: i-8999UIIIgjkkd,";
		List<String> instanceIdList = new ArrayList<String>();
		Matcher matcher = Pattern.compile("InstanceId:\\s*(\\S+),").matcher(instanceResultString);
    	while(matcher.find())
        	instanceIdList.add(matcher.group(1));
        System.out.println(instanceIdList);
	}
}

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