AarrayList的遍历方式（六种）

 public static void main(String[] args) {
        ArrayList<Integer> arrayList = new ArrayList<>();
        arrayList.add(10);
        arrayList.add(20);
        arrayList.add(30);
        //第一种遍历方式
        System.out.println(arrayList);//[10, 20, 30]
        //第二种遍历方式  for
        for (int i = 0; i < arrayList.size(); i++) {
            System.out.print(arrayList.get(i) + " ");//10 20 30
        }
        System.out.println();
        //第三种遍历方式  for-each
        for (int x:arrayList) {
            System.out.print(x + " ");//10 20 30
        }
        System.out.println();
        //第四种遍历方式  迭代器·
        Iterator<Integer> it = arrayList.iterator();
        while(it.hasNext()) {
            System.out.print(it.next()+" ");//10 20 30
        }
        System.out.println();
        //第五种遍历方式
        ListIterator<Integer> it1 = arrayList.listIterator();
        while(it1.hasNext()) {
            System.out.print(it1.next()+" ");//10 20 30
        }
        System.out.println();
        //6.从后往前遍历
        ListIterator<Integer> it2 = arrayList.listIterator(arrayList.size());
        while(it1.hasPrevious()) {
            System.out.print(it1.previous()+" ");//30 20 10 
        }
        System.out.println();
    }