1 package cn.itcast.p2.toolclass.collections.demo;
  2 
  3 import java.util.ArrayList;
  4 import java.util.Collections;
  5 import java.util.Comparator;
  6 import java.util.List;
  7 import java.util.TreeSet;
  8 
  9 import cn.itcast.p2.comparator.ComparatorByLength;
 10 
 11 public class CollectionsDemo {
 
 12 
 13     public static void main(String[] args) {
 14         // TODO Auto-generated method stub
 15         /*
 16          * Collections：是集合框架的工具類。
 17          * 裡面的方法都是靜態的。
 18          */
 19 //        demo_1();//排序
 20 //        demo_2();//折半 最值
 21         demo_3();//逆序 
 22         demo_4();//替換
 23     }
 
 24     
 25     private static void demo_4() {
 26         // TODO Auto-generated method stub
 27         List<String> list = new ArrayList<String>();
 28         
 29         list.add("abcde");
 30         list.add("cba");
 31         list.add("aa");
 32         
 33         System.out.println(list);
 
 34         Collections.replaceAll(list, "cba", "nba");//replaceAll相當於set(indexOf"cba","nba");
 35         System.out.println(list);
 36     }
 37 
 38     private static void demo_3() {
 39         // TODO Auto-generated method stub
 40         
 41 //        TreeSet<String> ts = new TreeSet<String>(Collections.reverseOrder());//原理就是下面這個方法
 42     /*    TreeSet<String> ts = new TreeSet<String>(new Comparator<String>() {
 43             public int compare(String o1, String o2) {
 44                 int temp = o2.compareTo(o1);
 45                 return temp;
 46             }
 47         });
 48         */ //自己實現
 49         
 50         //reverseOrder(Comparator<T> cmp),將一個已有比較器逆轉
 51         TreeSet<String> ts = new TreeSet<String>(Collections.reverseOrder(new ComparatorByLength()));
 52         ts.add("abc");
 53         ts.add("hahaha");
 54         ts.add("zzz");
 55         ts.add("aa");
 56         ts.add("cba");
 57         
 58         System.out.println(ts);
 59     }
 60 
 61     private static void demo_2() {
 62         // TODO Auto-generated method stub
 63         List<String> list = new ArrayList<String>();
 64         
 65         list.add("abcde");
 66         list.add("cba");
 67         list.add("aa");
 68         list.add("zzz");
 69         list.add("cba");
 70         list.add("nbaa");
 71         //折半要先排序
 72         Collections.sort(list);
 73         System.out.println(list);
 74         
 75         int index = Collections.binarySearch(list, "aaa");
 76         
 77         System.out.println("index="+index);
 78         
 79         //獲取最大值。
 80 //        String max = Collections.max(list);//max=zzz
 81         String max = Collections.max(list,new ComparatorByLength());
 82         System.out.println("max="+max);
 83     }
 84 
 85     public static void demo_1() {
 86         
 87         List<String> list = new ArrayList<String>();
 88         
 89         list.add("abcde");
 90         list.add("cba");
 91         list.add("aa");
 92         list.add("zzz");
 93         list.add("nbaa");
 94         System.out.println(list);
 95 
 96         
 97         
 98         //對list集合進行指定順序的排序。
 99 //        Collections.sort(list);
100 //        mySort(list);
101 //        mySort(list, new ComparatorByLength());
102         System.out.println(list);
103         
104         
105     }
106     //下面方法相當於Collections.sort(list,new ComparatorByLength);
107     /*
108     public static <T> void mySort(List<T> list,Comparator<? super T> comp) {
109             
110             for (int i = 0; i < list.size()-1; i++) {
111                 for (int j = i+1; j < list.size(); j++) {
112                     if (comp.compare(list.get(i),list.get(j)) >0) {
113 //                        T temp = list.get(i);
114 //                        list.set(i, list.get(j));
115 //                        list.set(j, temp);
116                         Collections.swap(list, i, j);
117                     }
118                 }
119             }
120         }
121     //介紹Collections.swap交換方法
122     /*
123     public static <T extends Comparable<? super T>> void mySort(List<T> list) {
124         for (int i = 0; i < list.size()-1; i++) {
125             for (int j = i+1; j < list.size(); j++) {
126                 if (list.get(i).compareTo(list.get(j))> 0 ) {
127 //                    T temp = list.get(i);
128 //                    list.set(i, list.get(j));
129 //                    list.set(j, temp);
130                     Collections.swap(list, i, j);
131                 }
132             }
133         }
134     }*/
135     
136     //相當於按自然順序方法升序排列Collections.sort
137     //public static <T extends Comparable<? super T>> void sort(List<T> list)
138     /*
139     public static <T extends Comparable<? super T>> void mySort(List<T> list) {
140         for (int i = 0; i < list.size()-1; i++) {
141             for (int j = i+1; j < list.size(); j++) {
142                 if (list.get(i).compareTo(list.get(j))> 0 ) {
143                     T temp = list.get(i);
144                     list.set(i, list.get(j));
145                     list.set(j, temp);
146                 }
147             }
148         }
149     }*/
150     
151     //傳入String型別的集合
152  /*    public static void mySort(List<String> list) {
153         
154         for (int i = 0; i < list.size()-1; i++) {
155             for (int j = i+1; j < list.size(); j++) {
156                 if (list.get(i).compareTo(list.get(j))> 0 ) {
157                     String temp = list.get(i);
158                     list.set(i, list.get(j));
159                     list.set(j, temp);
160                 }
161             }
162         }
163     }*/
164 
165 }