1、数字排序  

/**     * 数字排序     */    public static void testIntegerSort() {        List
     
       list = Arrays.asList(4, 2, 5, 3, 1);        System.out.println(list);//执行结果：[4, 2, 5, 3, 1]        //升序        list.sort((a, b) -> a.compareTo(b.intValue()));        System.out.println(list);//执行结果：[1, 2, 3, 4, 5]        //降序        list.sort((a, b) -> b.compareTo(a.intValue()));        System.out.println(list);//执行结果：[5, 4, 3, 2, 1]    }
     

2、字符串排序  

/**     * 字符串排序     */    public static void testStringSort() {        List
     
       list = new ArrayList<>();        list.add("aa");        list.add("cc");        list.add("bb");        list.add("ee");        list.add("dd");        System.out.println(list);//执行结果：aa, cc, bb, ee, dd        //升序        list.sort((a, b) -> a.compareTo(b.toString()));        System.out.println(list);//执行结果：[aa, bb, cc, dd, ee]        //降序        list.sort((a, b) -> b.compareTo(a.toString()));        System.out.println(list);//执行结果：[ee, dd, cc, bb, aa]    }
     

3、对象串排序 

class Person {        private String name;        private int age;        public Person() {        }        public Person(String name, Integer age) {            this.name = name;            this.age = age;        }        public String getName() {            return name;        }        public void setName(String name) {            this.name = name;        }        public int getAge() {            return age;        }        public void setAge(int age) {            this.age = age;        }        @Override        public String toString() {            return "Person{" +                    "name='" + name + '\'' +                    ", age=" + age +                    '}';        }    }

/**     * 对象串排序     */    public void testObjectSort() {        List
     
       list = new ArrayList<>();        list.add(new Person("三炮", 48));        list.add(new Person("老王", 35));        list.add(new Person("小明", 8));        list.add(new Person("叫兽", 70));        System.out.println(list); //执行结果：[Person{name='三炮', age=48}, Person{name='老王', age=35}, Person{name='小明', age=8}, Person{name='叫兽', age=70}]        //按年龄升序        list.sort((a, b) -> Integer.compare(a.age, b.getAge()));        System.out.println(list);//执行结果：[Person{name='小明', age=8}, Person{name='老王', age=35}, Person{name='三炮', age=48}, Person{name='叫兽', age=70}]        //按年龄降序        list.sort((a, b) -> Integer.compare(b.age, a.getAge()));        System.out.println(list);//执行结果：[Person{name='叫兽', age=70}, Person{name='三炮', age=48}, Person{name='老王', age=35}, Person{name='小明', age=8}]        //如果按姓名排序，其实就是按字符串排序一样    }