Java只能从文件中读取整数

Question

如果我有一个文件包含例如:

results1: 2, 4, 5, 6, 7, 8, 9
results2: 5, 3, 7, 2, 8, 5, 2

我想把每一行的整数加到一个数组中。一个数组对于每一行。我如何用只读取整数的代码做到这一点?

这是我到目前为止得到的

 String data = null;
    try {

        Scanner in = new Scanner(new File(myFile));
        while (in.hasNextLine()) {

                data = in.nextLine();
                numbers.add(data);

        }
        in.close();
    } catch (Exception e) {
    }

Answer 1

轻松。

每个数组一行，而不是两个。每行后面加一行。

将每行读取为String，丢弃前导"resultsX:"，并将剩余的部分分割为您选择的分隔符(例如，逗号)。将每个解析为整数并将其添加到List中。

我不认为引导"results1: "是增加任何价值。你怎么会有这个?

Answer 2

public static void main(String[] args) throws IOException {
    BufferedReader reader=null;
    try {
        reader = new BufferedReader(new FileReader(new File("PATH TO FILE")));
        // Only works if File allways contains at least two lines ... all lines after the second
        // will be ignored
        System.out.println(String.format("Array 1 : %s", Arrays.toString(stringArray2IntArray(readNextLine(reader)))));
        System.out.println(String.format("Array 2 : %s", Arrays.toString(stringArray2IntArray(readNextLine(reader)))));
    } finally {
        if (reader!=null) {
            reader.close();
        }
    }
}
private static Integer[] stringArray2IntArray(String[] numStrings) {
    List<Integer> result = new ArrayList<Integer>();
    for (int i = 0; i < numStrings.length; i++) {
        result.add(Integer.parseInt(numStrings[i].trim()));
    }
    return result.toArray(new Integer[numStrings.length]);
}
private static String[] readNextLine(BufferedReader reader) throws IOException {
    return reader.readLine().split(":")[1].split(",");    
} 

Answer 3

假设您有一个输入文件，像这样:

2,4,5,6,7,8,9
5,3,7,2,8,5,2

下面是加载它的代码片段:

    String firstLine = "";
    String secondLine = "";
    File file = new File("path/to/file");
    try {
        BufferedReader br = new BufferedReader(new FileReader(file)); 
        firstLine = br.readLine();
        secondLine = br.readLine();
    } catch(Exception e){
        e.printStackTrace();
    }
    String[] firstResult = firstLine.split(",");
    String[] secondResult = secondLine.split(",");
    int[] firstIntegers = new int[firstResult.length];
    for(int i = 0; i <= firstResult.length ; i++){
        firstIntegers[i] = Integer.parseInt(firstResult[i]);
    }
    int[] secondIntegers = new int[secondResult.length];
    for(int i = 0; i <= secondResult.length ; i++){
        firstIntegers[i] = Integer.parseInt(secondResult[i]);
    }

Answer 4

用BufferedReader br打开文件，然后逐行读取。将每行存储在一个int数组中，并将所有这些int数组添加到一个列表中。最后，这个列表将包含我们想要的所有int数组，所以迭代这个列表来做你接下来想做的任何事情。

String filePath = "/path/to/file";
BufferedReader br = null;
List<Integer[]> arrays = new ArrayList<>(); //this contains all the arrays that you want
try {
  br = new BufferedReader(new FileReader(filePath));
  String line = null;
  while ((line = br.readLine()) != null) {
      line = line.substring(line.indexOf(":")+2); //this starts the line from the first number
      String[] stringArray = line.split(", ");
      Integer[] array = new Integer[stringArray.length];
      for (int i = 0; i < stringArray.length; ++i) {
        array[i] = Integer.parseInt(stringArray[i]);
      }
      arrays.add(array);
  }      
} catch (FileNotFoundException ex) {
   System.err.println(ex);
} catch (IOException ex) {
   System.err.println(ex);
} finally {
   try {
     br.close();
   } catch (Exception ex) {
     System.err.println(ex);
   }      
}

由于数组列表保持插入顺序，那么，例如，arrays.get(3)将给你第四行数组(如果有这样一行)，arrays.size()将给你存储的行数(即int数组)。