我正在使用Java中的BufferedReader，并希望在讀取整數時獲得一些指導?？偠灾?，輸入文件的每一行將表示無向圖中的一條邊。它將包含兩個整數，即邊緣的端點，后跟一個實數，即邊緣的權重。最后一行將包含一個 -1，表示輸入的結束。我創建了一個BufferedReader對象并初始化了一個整數變量和該文件的格式如下： 0 1 5.0 1 2 5.0 2 3 5.0... 5 10 6.0 5 11 4.017 11 4.0-1public static void processFile(String inputFilePath) throws IOException { //Check to see if file input is valid if (inputFilePath == null || inputFilePath.trim().length() == 0) { throw new IllegalArgumentException("Error reading file."); } //Initialize required variables for processing the file int num = 0; int count = 0; try { //We are reading from the file, so we can use FileReader and InputStreamReader. BufferedReader fileReader = new BufferedReader(new FileReader(inputFilePath)); //Read numbers from the line while ((num = fileReader.read()) != -1) { //Stop reading file when -1 is reached //First input is the start //Second input is the end //Third input is the weight } } catch (IOException e) { throw new IOException("Error processing the file."); } } 這是我到目前為止所嘗試的，但我想知道我如何獲取每行代碼，并使第一個數字是“開始”變量，第二個數字是“結束”變量，第三個數字是“權重”變量？我在網上看到了一些創建數組的解決方案，但由于我的文件格式，我有點困惑。我可以幫助澄清有關以下方面的任何細節：
3 回答
狐的傳說
TA貢獻1804條經驗 獲得超3個贊
我會首先檢查我是否可以讀取該文件（您可以使用File.canRead（）來執行此操作）。接下來，我將編譯一個具有三個分組操作的正則表達式。然后我會使用BufferedReader.readLine（）來讀取文本行;read（） 調用返回單個字符。然后它只剩下解析匹配的行。而且我認為吞下原始異常只是為了重新刪除它（事實上，你以當前的方式丟失了所有堆棧跟蹤信息）。我看不出有什么意義。把這些放在一起，
public static void processFile(String inputFilePath) throws IOException {
File f = new File(inputFilePath);
if (!f.canRead()) {
throw new IllegalArgumentException("Error reading file.");
}
// Initialize required variables for processing the file
try (BufferedReader fileReader = new BufferedReader(new FileReader(inputFilePath))) {
Pattern p = Pattern.compile("^\\s*(\\d+)\\s+(\\d+)\\s+(\\d.+)$");
String line;
while ((line = fileReader.readLine()) != null) {
Matcher m = p.matcher(line);
if (m.matches()) {
int start = Integer.parseInt(m.group(1));
int end = Integer.parseInt(m.group(2));
double weight = Double.parseDouble(m.group(3));
System.out.printf("start=%d, end=%d, weight=%.2f%n", start, end, weight);
}
}
}
}
冉冉說
TA貢獻1877條經驗 獲得超1個贊
切換到readLine并使用掃描儀：
public static void processFile(String inputFilePath) throws IOException {
// Check to see if file input is valid
if (inputFilePath == null || inputFilePath.trim()
.length() == 0) {
throw new IllegalArgumentException("Error reading file.");
}
// Initialize required variables for processing the file
String line;
int count = 0;
// We are reading from the file, so we can use FileReader and InputStreamReader.
try (BufferedReader fileReader = new BufferedReader(new FileReader(inputFilePath))) {
// Read numbers from the line
while ((line = fileReader.readLine()) != null) { // Stop reading file when -1 is reached
Scanner scanner = new Scanner(line);
// First input is the start
int start = scanner.nextInt();
if (start == -1) {
break;
}
// Second input is the end
int end = scanner.nextInt();
// Third input is the weight
double weight = scanner.nextDouble();
// do stuff
}
} catch (IOException e) {
throw new IOException("Error processing the file.");
}
}
心有法竹
TA貢獻1866條經驗 獲得超5個贊
而不是使用，你可以只是使用然后使用分裂與你的分隔符是三個空格，我想？readreadLine
try (BufferedReader fileReader = new BufferedReader(new FileReader(inputFilePath))) {
String line;
while(!(line = fileReader.readLine()).equals("-1")) {
String[] edge = line.split(" ");
int start = Integer.parseInt(edge[0]);
int end = Integer.parseInt(edge[1]);
double weight = Double.parseDouble(edge[2]);
}
} catch (IOException e) {
e.printStackTrace();
}
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