lambda使用

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public static void main(String[] args) {        Map<String, Object> map = new HashMap<>();        map.put("1", "111");        map.put("2", "2222");        //1.需求：打印输出已经排好序的字符串数组中长度大于20 ，并且为其添加hello ;        //数据源        String[] players = {"Rafael Nadal", "Novak Djokovic",                "Stanislas Wawrinka", "David Ferrer",                "Roger Federer", "Andy Murray",                "Tomas Berdych", "Juan Martin Del Potro",                "Richard Gasquet", "John Isner"};        //排序        Arrays.sort(players);        //转化为list操作        List<String> list = Arrays.asList(players);        //过滤长度大于20 ，并为其添加hello 输出          list.stream().filter(a -> a.startsWith("J")).map(a -> a += " hello").forEach(player -> System.out.println(player));        list.stream().filter(a -> a.length() > 20).map(a -> a += " hello").forEach(player -> System.out.println(player));        //2.需求：对多个对象，按照年龄进行排序输出：        List<Student> peopleList = new ArrayList<>();        peopleList.add(new Student("a", 17));        peopleList.add(new Student("b", 16));        peopleList.add(new Student("c", 19));        peopleList.add(new Student("d", 15));        //按照年龄排序：        Collections.sort(peopleList, (Student a, Student b) -> a.getAge().compareTo(b.getAge()));        peopleList.stream().forEach(a -> System.out.println(a.getAge()));    }