Java用于读取200万行文本文件的最快方式 [英] Java Fastest way to read through text file with 2 million lines

问题描述

目前我正在使用扫描仪/文件阅读器并使用whilenextline。我认为这种方法效率不高。有没有其他方法来读取具有类似功能的文件？

Currently I am using scanner/filereader and using while hasnextline. I think this method is not highly efficient. Is there any other method to read file with the similar functionality of this?

public void Read(String file) {
        Scanner sc = null;


        try {
            sc = new Scanner(new FileReader(file));

            while (sc.hasNextLine()) {
                String text = sc.nextLine();
                String[] file_Array = text.split(" ", 3);

                if (file_Array[0].equalsIgnoreCase("case")) {
                    //do something
                } else if (file_Array[0].equalsIgnoreCase("object")) {
                    //do something
                } else if (file_Array[0].equalsIgnoreCase("classes")) {
                    //do something
                } else if (file_Array[0].equalsIgnoreCase("function")) {
                    //do something
                } 
                else if (file_Array[0].equalsIgnoreCase("ignore")) {
                    //do something
                }
                else if (file_Array[0].equalsIgnoreCase("display")) {
                    //do something
                }
            }

        } catch (FileNotFoundException e) {
            System.out.println("Input file " + file + " not found");
            System.exit(1);
        } finally {
            sc.close();
        }
    }

推荐答案

你会发现 BufferedReader.readLine（） 可以满足您的需求：您可以每秒读取数百万行。您的字符串拆分和处理更可能导致您遇到的任何性能问题。

You will find that BufferedReader.readLine() is as fast as you need: you can read millions of lines a second with it. It is more probable that your string splitting and handling is causing whatever performance problems you are encountering.

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