Question

我想在基于序列的列表中将文件拆分为Header和详细信息。

想要使用标题和细节拆分文本文件我试过这样的事情，但没有帮助。

我想调用迭代器的前一次迭代，但我不能......

文件：

H＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

H＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

H＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;

L＆GT;＆GT;＆GT;＆GT;＆GT;＆GT;＆GT; ...

我想：

列出1，H，L，L，L

列出2，H，L，L

列出3与H，L

代码尝试：

 List<String> poString = new ArrayList<String>();
    if(poString !=null && poString.size() > 0)
            {      
               ListIterator<String> iter = poString.listIterator();
               while(iter.hasNext())
               {
                String tempHead = iter.next();
                List<String> detailLst = new ArrayList<String>();
                if(tempHead.startsWith("H"))
                 {
                    while(iter.hasNext())
                    {
                        String detailt = iter.next();
                        if(!detailt.startsWith("H"))
                          detailLst.add(detailt);
                        else
                        {
                            iter.previousIndex();
                        }
                    }
                 }
               }

Answer 1

试试这个（未经测试）：

BufferedReader br = new BufferedReader(new FileReader("file.txt"));
try {
        List<StringBuilder> myList = new List<StringBuilder>();
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();
        while (line != null) {
        if (line[0] == 'H')
        {
            myList.add(sb);  
            sb = new StringBuilder();                               
        }   
        sb.append(line[0]);        
        line = br.readLine();
    }
} finally {
    br.close();
}

Answer 2

你可以使用它..

public static void main(String a[]) throws Exception
{
    ArrayList<String> headers=new ArrayList();
    ArrayList<String> lines=new ArrayList();
    HashMap<String, ArrayList<String>> map = new HashMap<String, ArrayList<String>>(); 
    File f= new File("inputfile.txt");
    Scanner scanner = new Scanner(f);
    try {
      while (scanner.hasNextLine()){
       String ss=scanner.nextLine();
       String key= String.valueOf(ss.charAt(0));
       if ( map.containsKey(key))
       {
           ArrayList<String> temp=(ArrayList) map.get(key);
           temp.add(ss);
           map.put(key, temp);
       }
       else
       {
           ArrayList<String> temp= new ArrayList();
           temp.add(ss);
           map.put(key, temp);
       }
      }
    }
      catch(Exception e)
      {
          throw e;
      }

}

Answer 3

据我了解，最终文件中有多少H..lines，您希望有多少List<String>。

如果您不知道确切的数字（在您的示例中，它是3），那么您有一个列表列表（List<List<String>>）。

//read the file, omitted

List<List<String>> myList = new ArrayList<<List<String>>();
List<String> lines = null;
boolean createList = false;
while (line != null) {
    if (line.startsWith("H")){
      myList.add(lines);
      lines = new ArrayList<String>();
    }
//if the 1st line of your file not starting with 'H', NPE, you have to handle it
   lines.add(line);
   line=readnextlineSomeHow(); //read next line
}

上述代码可能不会开箱即用，但它会为您提供想法。

Answer 4

尝试这个，我已经尝试了一点，我的工作

    BufferedReader br = new BufferedReader(new FileReader("file.txt"));
    ArrayList<ArrayList<String>> result = new ArrayList<> ();
    int numlines =0;
    try {
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();
        while (line != null) {
            if (line.startsWith("H"))
            { 
                   result.add(new ArrayList<String>());
                   result.get(numlines).add("H");

                   line = br.readLine();

                   while(line != null && !line.startsWith("H")){
                       if(line.startsWith("L")) result.get(numlines).add("L");
                       line = br.readLine();
                   }
                   ++numlines;
            }        
            else line = br.readLine();
        }

    } finally {
        br.close();
    }

如何基于startswith拆分文本文件

4 个答案: