Java/Android -在匿名内部类中更新ArrayList

ArrayList<String> arrayList = new ArrayList<>();
arrayList.add("元素1");
arrayList.add("元素2");

new Thread(new Runnable() {
    @Override
    public void run() {
        arrayList.add("新元素");
    }
}).start();

import java.util.ArrayList;

public class Example {
    public static void main(String[] args) {
        ArrayList<String> arrayList = new ArrayList<>();
        arrayList.add("元素1");
        arrayList.add("元素2");

        new Thread(new Runnable() {
            @Override
            public void run() {
                arrayList.add("新元素");
            }
        }).start();

        System.out.println(arrayList);
    }
}