如何在 java 中的字符串中查找长双精度数

Question

我正在尝试提取存在于文本文件每一行中的端到端延迟值。我使用正则表达式只获取每行末尾的数字，但正则表达式出现错误：

illegal escape character

此外，我需要打开文件以获取每一行并提取端到端延迟值并将其存储在另一个文本文件中（所有提取的端到端延迟）。

这是我的代码：

import java.awt.Desktop;
import java.io.File;
import java.io.IOException;
import javax.swing.filechooser.FileSystemView;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author DevAdmin
 */
public class extarctor {

    public static final String s_example = "sender id: 116/sequence number: 117/depth: 443/sending time: 4/23/2020 2:08:54 AM/data: Hello I am SN: 116 this is event # 117 from my sideEnd-End Delay is:2.74550137092987E-05delay registered @ Sink: 621.932901880787";

    public static void main(String[] args) throws IOException {
        //text file, should be opening in default text editor
        File file = new File(FileSystemView.getFileSystemView().getHomeDirectory().getAbsolutePath()+ "/res/End-End-Delay.txt");

        //first check if Desktop is supported by Platform or not
        if(!Desktop.isDesktopSupported()){
            System.out.println("Desktop is not supported");
            return;
        }

        Desktop desktop = Desktop.getDesktop();
        if(file.exists()) System.out.println("Good, keep going!");

        System.out.println(s_example.matches("\d+\.\d+$"));



    }


}

Answer 1

使用Matcher::group提取所需的数字。

演示：

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) {
        String s_example = "sender id: 116/sequence number: 117/depth: 443/sending time: 4/23/2020 2:08:54 AM/data: Hello I am SN: 116 this is event # 117 from my sideEnd-End Delay is:2.74550137092987E-05delay registered @ Sink: 621.932901880787";

        Pattern pattern = Pattern.compile("\d+.\d+$");
        Matcher matcher = pattern.matcher(s_example);
        while (matcher.find()) {
            System.out.println(matcher.group());
        }
    }
}

输出：

621.932901880787

如何在 java 中的字符串中查找长双精度数

How to find a long double number in a string in java

java

regex

qregularexpression