1. 程式人生 > >Java集合類Collections常用方法總結

Java集合類Collections常用方法總結

public class CollectionsTest {

    public static void main(String[] args) {
        List<Integer> list = new ArrayList<Integer>();
        list.add(34);
        list.add(55);
        list.add(56);
        list.add(89);
        list.add(12);
        list.add(23);
        list.add(126);
        System.out
.println(list); //對集合進行排序 Collections.sort(list); System.out.println(list); //對集合進行隨機排序 Collections.shuffle(list); System.out.println(list); //獲取集合最大值、最小值 int max = Collections.max(list); int min = Collections.min(list); System.out
.println("Max:" + max + " Min: " + min); List<String> list2 = Arrays.asList("Monday,Tuesday,Wednesday,Thursday,Friday,Saturday,Sunday".split(",")); System.out.println(list2); //查詢集合指定元素,返回元素所在索引 //若元素不存在,n表示該元素最有可能存在的位置索引 int index1 = Collections.binarySearch
(list2, "Thursday"); int index2 = Collections.binarySearch(list2, "TTTTTT"); System.out.println(index1); int n = -index2 - 1; //查詢子串在集合中首次出現的位置 List<String> subList = Arrays.asList("Friday,Saturday".split(",")); int index3 = Collections.indexOfSubList(list2, subList); System.out.println(index3); int index4 = Collections.lastIndexOfSubList(list2, subList); System.out.println(index4); //替換集合中指定的元素,若元素存在返回true,否則返回false boolean flag = Collections.replaceAll(list2, "Sunday", "tttttt"); System.out.println(flag); System.out.println(list2); //反轉集合中的元素的順序 Collections.reverse(list2); System.out.println(list2); //集合中的元素向後移動k位置,後面的元素出現在集合開始的位置 Collections.rotate(list2, 3); System.out.println(list2); //將集合list3中的元素複製到list2中,並覆蓋相應索引位置的元素 List<String> list3 = Arrays.asList("copy1,copy2,copy3".split(",")); Collections.copy(list2, list3); System.out.println(list2); //交換集合中指定元素的位置 Collections.swap(list2, 0, 3); System.out.println(list2); //替換集合中的所有元素,用物件object Collections.fill(list2, "替換"); System.out.println(list2); //生成一個指定大小與內容的集合 List<String> list4 = Collections.nCopies(5, "哈哈"); System.out.println(list4); //為集合生成一個Enumeration List<String> list5 = Arrays.asList("I love my country!".split(" ")); System.out.println(list5); Enumeration<String> e = Collections.enumeration(list5); while (e.hasMoreElements()) { System.out.println(e.nextElement()); } } }