package cn.burce.Collection; import java.util.ArrayList; import java.util.Collections; import java.util.List; //集合操作的工具类collections // public class collectionsDemo { public static void main(String[] args) { fun(); fun1(); fun2(); } // Collections.sort()对list集合进行排序 public static void fun() { List<String> list = new ArrayList<String>(); list.add("abc1"); list.add("abc3"); list.add("abc2"); list.add("abc4"); System.out.println(list); Collections.sort(list); System.out.println(list); } // collections.binarysearch查找元素 public static void fun1() { List<String> list = new ArrayList<String>(); list.add("abc1"); list.add("abc3"); list.add("abc2"); list.add("abc4"); Collections.sort(list);// 二分查找时先进行升序排序 int a = Collections.binarySearch(list, "abc2"); System.out.println(a); } // collections.shuffle对元素随机排列 public static void fun2() { List<String> list = new ArrayList<String>(); list.add("abc1"); list.add("abc3"); list.add("abc2"); list.add("abc4"); Collections.sort(list);// 二分查找时先进行升序排序 Collections.shuffle(list); System.out.println(list); } }