Java List 的merge

List的merge的基本思路与数组是相同的，但是在具体实现的时候还是有一些困难的。由于List的Iterator没有Prev函数。本文采用简单测量规避了这个问题。

有兴趣的同学参照一下下面的示例。

 

 

 1 package tests;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Iterator;
 5 import java.util.List;
 6 
 7 /*
 8  * a demo of merge to Lists, whose values are both sorted
 9  */
10 public class mergeLists {
11 
12     /**
13      * @param args
14      */
15     public static void main(String[] args) {
16         // two test lists with sequential int values
17         List<Integer> added_list = new ArrayList<Integer>();
18         List<Integer> base_list = new ArrayList<Integer>();
19         for(int i = 0; i < 20; i+=2){
20             base_list.add(i);
21         }
22         for(int i = -3; i < 30; i+=3){
23             added_list.add(i);
24         }
25         System.out.println("base " +base_list);
26         System.out.println("add " + added_list);
27         Iterator<Integer> added_iter = added_list.iterator();
28         Iterator<Integer> base_iter = base_list.iterator();
29         int lbase = 0;
30         // since there is no "Prev" function for Interator,
31         // we need to use this boolean to record whether
32         // it needs to move next
33         boolean base_added = true;
34         // begin to merge
35         for(;added_iter.hasNext();){
36             int ladded = added_iter.next();
37             for(;(base_added && base_iter.hasNext()) || !base_added;){
38                 if(base_added){
39                     lbase = base_iter.next();
40                 }
41                 if(ladded > lbase){
42                     System.out.print("b"  + lbase + ", ");
43                     base_added = true;
44                 }
45                 else{
46                     base_added = false;
47                     System.out.print("k, ");
48                     break;
49                 }
50             }
51             System.out.print("a" + ladded + ", ");
52         }
53         // deal with left data in list b
54         for(;(base_added && base_iter.hasNext()) || !base_added;){
55             if(base_added){
56                 lbase = base_iter.next();
57             }
58             System.out.print("b"  + lbase + ", ");
59             base_added = true;
60         }
61 
62     }
63 
64 }