List 集合遍歷方式
阿新 • • 發佈:2021-09-08
List 集合的幾種遍歷方式
public class ListDemo { public static void main(String[] args) { List<Fruit> fruitList = new ArrayList<>(); fruitList.add(new Fruit(1, "apple", "紅色", 120.00)); fruitList.add(new Fruit(2, "orange", "黃色", 140.00)); fruitList.add(new Fruit(3, "guava", "灰色", 160.00)); fruitList.add(new Fruit(4, "pear", "黃色", 180.00)); fruitList.add(new Fruit(5, "mango", "黃色", 240.00)); fruitList.add(new Fruit(6, "watermelon", "綠色", 260.00)); // 遍歷方式一 // 對於 List 集合判空 if (Objects.nonNull(fruitList) && !fruitList.isEmpty()) { for (int i = 0; i < fruitList.size(); i++) { System.out.println(i); } } // 遍歷方式二 if (Objects.nonNull(fruitList) && !fruitList.isEmpty()) { for (Fruit fruit : fruitList) { System.out.println(fruit); } } // 遍歷方式三 if (Objects.nonNull(fruitList) && !fruitList.isEmpty()) { ListIterator<Fruit> iterator = fruitList.listIterator(); while (iterator.hasNext()) { System.out.println(iterator.next()); } } // 遍歷方式四 if (Objects.nonNull(fruitList) && !fruitList.isEmpty()) { fruitList.forEach((x) -> System.out.println(x)); } } }