multithreading (unable to accessing global variables like ann)

I am trying multithreaded annotation, but complaining with accessing ann
from run(). Do you have any idea?

Properties props = new Properties();
props.setProperty("annotators", "tokenize,ssplit,parse");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);

Annotation ann = new Annotation("your sentence here");
for (int i = 0; i < 100; ++i) {
    new Thread() {
        @Override public void run() {
          pipeline.annotate(ann);  
          Tree tree = ann.get(SentencesAnnotation.class).get(0).get(TreeAnnotation.class);
        }
    }.start();
}