package gather;import java.util.ArrayList;import java.util.Collections;public class CollecSortTest {    public static void main(String[] args) {                //        System.out.println(list.isEmpty()); 判断结合是否为空                ArrayList
     
       list1   = new ArrayList<>();                 Collections.sort(list1); //方法1                        list1.add("222");        list1.add("1");        list1.add("444");        list1.add("33");//        list1.sort(new ComparatorOne());  //方法2                Collections.sort(list1, ( first, second) -> first.length() - second.length());//  方法5 lambda表达式                         ArrayList
      
        list2   = new ArrayList<>();         Student student1 = new Student();        student1.setAge(1);                Student student2 = new Student();        student2.setAge(2);                Student student3 = new Student();        student3.setAge(3);                list2.add(student3);        list2.add(student2);        list2.add(student1);//        list2.sort(new ComparatorTwo()); //方法3                Collections.sort(list2, ( first, second) -> second.getAge() - first.getAge());//  方法5 lambda表达式                System.out.println("true");             }}
      
     

 

package gather;import java.util.Comparator;public class ComparatorOne implements Comparator
     
       {    @Override    public int compare(String arg0, String arg1) {        System.out.println("---ComparatorOne---");         return arg0.length() - arg1.length();    } }
     

package gather;import java.util.Comparator;public class ComparatorTwo implements Comparator
     
      {    @Override    public int compare(Student o1, Student o2) {                System.out.println("---ComparatorTwo---");         return o1.getAge()-o2.getAge();    }        }