Java List操作详解-优快云博客

本文链接：https://blog.youkuaiyun.com/u013553694/article/details/103638833

1.增加

1.增加

        List<String> list = new ArrayList();
        list.add("a");// [a],向集合中追加元素
        System.out.println(list);// [a],不是地址，重写了toString方法
        list.add(1, "b");// [a,b],向集合的指定位置中追加元素
        list.addAll(list);//[a, b, a, b], 向集合追加一个collection，只可追加collection，由于java不提供collection的实现，由它的下级接口来实现
        System.out.println(list);
        list.addAll(4, list);// [a, b, a, b, a, b, a, b],与上述含义相同， “4”意为追加元素所放的位置

2.删除

        List<String> list = new ArrayList<>();
        list.add("a");list.add("b");list.add("c");list.add("d");list.add("e");
        list.remove(0);//[b,c,d,e]
        System.out.println(list.remove(0));//b
        list.remove("c");//[d, e]
        list.add("e");list.add("f");
        List<String> list1 = new ArrayList<>();
        list1.add("d");list1.add("e");
        list.removeAll(list1);//[f]
        list.clear();//[]
        list.add("a");list.add("b");list.add("c");list.add("d");list.add("e");
        list.retainAll(list1);
        System.out.println(list);//[d, e]

3.修改

        List<String> list = new ArrayList<>();
        list.add("a");list.add("b");list.add("b");list.add("a");
        list.replaceAll(t -> t + 1);//[a1, b1, c1, a1]
        list.set(2, "c");
        System.out.println(list);//[a1, b1, c, a1]

4.查询

        List<String> list = new ArrayList<>();
        list.add("a");list.add("b");
        Integer indexOf = list.indexOf("a");//0
        String get = list.get(1);//b
        Boolean contains = list.contains("a");//true
        Boolean isEmpty = list.isEmpty();//false

5.遍历

        List<String> list = new ArrayList<>();
        list.add("a");list.add("b");
        Iterator it=list.iterator();
        while(it.hasNext()) {
            String string=(String) it.next();
            System.out.println(string);
        }
        //方式二：
        for (Object o:list) {
            System.out.println(o);
        }
        //方式三：
        for(int s=0;s<list.size();s++) {
            System.out.println(list.get(s));
        }

6.排序

        List<String> list = new ArrayList<>();
        list.add("c");
        list.add("b");
        list.add("a");
        list.add("f");
        list.sort((s1,s2)-> s1.compareTo(s2));//[a, b, c, f]
        list.sort((s1,s2)-> s2.compareTo(s1));//[f, c, b, a]


        List<String> list = new ArrayList<>();
        list.add("c");
        list.add("b");
        list.add("a");
        list.add("f");
        list.sort(new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                return o1.compareTo(o2);
            }
        });//[a, b, c, f]
        list.sort(new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                return o2.compareTo(o1);
            }
        });//[f, c, b, a]

7.其他

7.1获得子串

        List<String> list = new ArrayList<>();
        list.add("a");list.add("b");list.add("c");list.add("d");list.add("e");
        List<String> list1 = list.subList(1,3);//[b, c]

7.2转变为数组

        List<String> list = new ArrayList<>();
        list.add("a");
        list.add("b");
        list.add("c");
        Object[] ob = list.toArray();//[a, b, c]
        System.out.println(Arrays.toString(ob));

        String[] s = new String[list.size()];
        System.out.println(list);//[a, b, c]
        System.out.println(Arrays.toString(s));//[null, null, null]
        list.toArray(s);
        System.out.println(list);//[a, b, c]
        System.out.println(Arrays.toString(s));//[a, b, c]