package java_test; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; class clearListDemo{//清除list public void clearList(){ List<String> list=new ArrayList<String>(); list.add("a"); boolean e=list.isEmpty(); System.out.println(e); list.clear();//清除list里的所有元素 boolean m=list.isEmpty(); System.out.println(m); System.out.println(list); } public void sortList(){//list排序 List<String> list=new ArrayList<String>(); list.add("d"); list.add("c"); list.add("a"); Collections.sort(list);//集合排序,升序排序 System.out.println(list); } } public class arrayToArrayListDemo { public static void main(String[] args) { Integer [] i=new Integer[]{1,2,3}; List<Integer> t=Arrays.asList(i); List<Integer> list =new ArrayList<>(t);//将数组转换为ArrayList的正确方式 System.out.println(list); clearListDemo c=new clearListDemo(); c.clearList(); c.sortList(); } }