从导入到 hash map 的文本文件中打印数据，忽略字符

Question

I have a text file that contains the following:

example.txt

#ignore
#ignore line
#ignore line again
1234567
8940116
12131415

I want to read in the example.txt file into eclipse and add the data into a hashmap. I want the list to be arranged in numerical order and I want it to ignore any comments(any text with #) in the text file. I would like to print the hashmap as follows:

output:

1234567
8940116
12131415

Answer 1

You don't need a hashmap for storing just Strings. Maps are for key value pairs. If you want to put each line from file into a collection use Lists. ArrayLists, LinkedList maintain insertion order. You can use any of them. If you want sorted list you can use TreeList.

    BufferedReader reader;
    List<String> list = new ArrayList<String>();
    try {
        reader = new BufferedReader(new FileReader(
                "example"));
        String line = reader.readLine();
        while (line != null) {
            if(!line.startsWith("#"){
                list.add(line);
              }
              line = reader.readLine();
        }
        reader.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 2

Thr purpose of a Map is to store pairs Key/Value , for a single collection you may use a List it's far more efficient, the printing part is you job whatever the type of collection is

List<String> values = new ArrayList<>();
try (BufferedReader reader = new BufferedReader(new FileReader("filename"))) {
    String line;
    while ((line = reader.readLine()) != null) {
        if (!line.startsWith("#")) {
            values.add(line);
        }
    }
} catch (IOException e) {
    e.printStackTrace();
}

for (String v : values)
    System.out.println(v);