forEach循环对集合进行循环时，需判断是否为null；

public class Foreach {

    public static void main(String[] args) {
        List<String> strings = new ArrayList<>();
        strings.add("Alis");

        for (String name:strings){
            System.out.println(name);
        }
    }
}

public class Foreach {
    public Foreach() {
    }

    public static void main(String[] args) {
        List<String> strings = new ArrayList();
        strings.add("Alis");
        Iterator var2 = strings.iterator();

        while(var2.hasNext()) {
            String name = (String)var2.next();
            System.out.println(name);
        }

    }
}