排序行包括在行

Question

我有以下文本文件（offline.txt）：

# Timestamp, X, Y, MAC Address of AP, RSS 
1395444273179 35.19967269897461 19.1965389251709 28:c6:8e:85:80:d3 -71 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a1 -75 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a2 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b1 -84 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b2 -85 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b0 -85 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a0 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:41 -75 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:40 -73 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:42 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:52 -96 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:50 -97 

我想根据在数目的文件的行进行排序文件的第5列按降序排列，如果重复一个值，则重复值的顺序无关紧要。

例如，这是所需的输出（offline_out.txt）我想上一个特别的文本文件：

# Timestamp, X, Y, MAC Address of AP, RSS 
1395444273179 35.19967269897461 19.1965389251709 28:c6:8e:85:80:d3 -71 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:40 -73 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:42 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a0 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a2 -74 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:a1 -75 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b1 -84 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b2 -85 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:8e:e9:b0 -85 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:52 -96 
1395444273179 35.19967269897461 19.1965389251709 00:1a:1e:87:04:50 -97 

我知道如何读取这个文件，我知道了“排序”功能java可以帮助我排序。 所以我的想法是提取第五行中的所有数字，将它们保存在一个向量中，然后对向量进行排序并找到一种方法将数字指定给特定的行，因此一旦数字被排序，行也被排序，然后将它们保存到另一个文件。关于如何编程的任何想法？

这是程序我到目前为止：

public class extract { 
    public static void main (String[] args) throws java.lang.Exception 
    { 
    File inputFile = new File("offline.txt"); 
    File tempFile = new File("offline_out.txt"); 

    BufferedReader reader = new BufferedReader(new FileReader(inputFile)); 
    BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile)); 

    //while to read all the lines, but how can I store only the numbers to a vector an associate them to a specific row? 
     while((currentLine = reader.readLine()) != null) { 
      } 
    } 

    //to save the output file 
    boolean successful = tempFile.renameTo(inputFile); 

    } 

Answer 1

使用一个TreeMap来存储对应于las的行在特定线路

TreeMap<Integer, String> map = new TreeMap<Integer, String>(); 
while((currentLine = reader.readLine()) != null) { 

    // split the line and use the last value as key 
    if (!currentLine.contains("Timestamp")) 
     map.put(Integer.parseInt(currentLine.split("\\s+")[4]), currentLine); 
    else 
     map.put(0, currentLine); 
} 

最后，你可以打印和看到的结果（或者你可以写一个文件，请你）T编号：

for(Integer key : map.descendingKeySet()) 
    System.out.println(map.get(key)); 

重复的线路不被捕获在上述中，更新所述结构以捕获它

使用地图与Arraylist，存储对应于所述特定数目

0123的线

TreeMap<Integer, ArrayList<String>> map = new TreeMap<Integer, ArrayList<String>>(); 
while((currentLine = reader.readLine()) != null) { 

    int key; 
    if (!currentLine.contains("Timestamp")) 
     // split the line and use the last value as key 
     key = Integer.parseInt(currentLine.split("\\s+")[4]; 
    else 
     key = 0; 
    ArrayList<String> lines; 
    if (!map.contains(key)) //if the key doesn't exist create a new arraylist 
     lines = new ArrayList<String>();    
    else // if the key exists use the arraylist in the map 
     lines = map.get(key); 
    lines.add(currentLine); 
    map.put(key, lines); 
} 

和用于打印：

for(Integer key : map.descendingKeySet()) 
    for(String line : map.get(key)) 
     System.out.println(line); 

Answer 2

如何只使用String.split

String [] arr = currentLine.split ("\\s+"); 

尝试使用树形图存储

http://docs.oracle.com/javase/6/docs/api/java/util/TreeMap.html

Answer 3

创建具有两个字段，number和line值对象bean类。执行comparable并覆盖该类中的compareTo方法。在扫描文件时填充此Bean类的ArrayList。然后对ArrayList进行排序。