import java.util.HashMap;
import java.util.Map;

public class TestMapDefaultCompute {

	public static void main(String[] args) {
		Map<String, Integer> map = new HashMap<>();
		new Thread(()-> {try {
			Thread.sleep(100);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
			map.put("foo", 55);}).start();
		new Thread(()-> {
			map.compute("foo", (k, v) ->  v + 41);
			System.out.println(map);
		                }).start();
	
		System.out.println(map);
	}

}