JAVA 中清除StringBuffer中的内容

在开发程序的时候，经常使用StringBuffer类来进行字符串的拼接。

如果在循环中来反复的做字符串拼接时，会清空stringbuffer中的内容，然后再拼接新的字符串信息。

例如：

stringbuffer sb ;
for (userinfo ui : userinfolist) {
    sb = new stringbuffer("");
    sb.append("姓名:");
    sb.append(ui.getname());
    sb.append("  ");
    sb.append("年龄:");
    sb.append(ui.getage());
    system.out.println(sb.tostring());
}

　　以下为《JAVA语言程序设计》进阶版 27章编程题2 本人编写的作业，涉及到以上用法。

 1 package Graph_27;
 2 
 3 import java.io.*;
 4 
 5 
 6 public class Exercise27_2 {
 7   public Exercise27_2() {
 8       
 9   }
10   
11   public static void main(String[] args) throws Exception {
12       String[] vertices = {"Seattle", "San Francisco", "Los Angeles",
13               "Denver", "Kansas City", "Chicago", "Boston", "New York",
14               "Atlanta", "Miami", "Dallas", "Houston"};
15 
16             int[][] edges = {
17               {0, 1}, {0, 3}, {0, 5},
18               {1, 0}, {1, 2}, {1, 3},
19               {2, 1}, {2, 3}, {2, 4}, {2, 10},
20               {3, 0}, {3, 1}, {3, 2}, {3, 4}, {3, 5},
21               {4, 2}, {4, 3}, {4, 5}, {4, 7}, {4, 8}, {4, 10},
22               {5, 0}, {5, 3}, {5, 4}, {5, 6}, {5, 7},
23               {6, 5}, {6, 7},
24               {7, 4}, {7, 5}, {7, 6}, {7, 8},
25               {8, 4}, {8, 7}, {8, 9}, {8, 10}, {8, 11},
26               {9, 8}, {9, 11},
27               {10, 2}, {10, 4}, {10, 8}, {10, 11},
28               {11, 8}, {11, 9}, {11, 10}
29             };
30 
31             Graph<String> graph = new UnweightedGraph<String>(edges, vertices);
32            
33             File file = new File("Graph.txt");
34             if(!file.exists()) {
35                 PrintWriter date = new PrintWriter(file);
36                 int numberOfVertices = graph.getVertices().size();
37                 date.println(numberOfVertices);
38                 StringBuffer s;
39                 for(int i = 0; i < numberOfVertices; i++) {
40                  s = new StringBuffer();
41                  s.append(i + " ");
42                  for(int j = 0; j < graph.getNeighbors(i).size(); j++) {
43                      s.append(graph.getNeighbors(i).get(j) + " ");
44                  }
45                  date.println(s);
46                 }
47                 date.close();
48             }
49             else
50             System.out.println("file is existed");    
51   }
52 }

posted on 2012-04-23 20:46 qqfc650 阅读(1411) 评论(2) 编辑收藏举报

JAVA 中 清除StringBuffer中的内容

JAVA 中清除StringBuffer中的内容