import java.util.*;

class AAA {
    private void foo(List<String> list) {
        for (String val : list) {
            if (val == null) continue;
            val = val.trim();
            if (val.isEmpty()) continue;
            try {
                Integer.parseInt(val);
            } catch (NumberFormatException e) {
                continue;
            }
            throw new IllegalArgumentException("Should not be a number!");
        }
    }

}