【问题标题】:java read specific lines from filejava从文件中读取特定行
【发布时间】:2020-11-26 11:25:19
【问题描述】:

我有一个巨大的 txt 文件,其中包含重复部分,从 HouseName 开始,到 RentPrice,如下文所示:

[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]getHouseName: house1
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]
[04:06:04s] [startedRetrieving]getHouseName: house2
[04:06:04s] [startedRetrieving]price(in doll) [min: 1004, max 1100]
[04:06:04s] [startedRetrieving]squaremtr(in doll) [min: 85, max 99]
[04:06:04s] [startedRetrieving]sellVal(in doll) [min: 950, max: 1050]
[04:06:04s] [startedRetrieving]random useless text
[04:06:04s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 290]
[04:09:04s] [startedRetrieving]getHouseName: house3
[04:09:04s] [startedRetrieving]price(in doll) [min: 1099, max: 1200]
[04:09:04s] [startedRetrieving]squaremtr(in doll) [min: 90, max: 110]
[04:09:04s] [startedRetrieving]random useless text
[04:09:04s] [startedRetrieving]random useless text
[04:09:04s] [startedRetrieving]sellVal(in doll) [min: 1100, max: 1300]
[04:09:04s] [startedRetrieving]random useless text
[04:09:04s] [startedRetrieving]rentPrice(in doll) [min: 199, max: 300]

现在,我使用扫描仪方法逐行阅读,我想将每个房间的行附加到字符串中。例如:

[04:04:04s] [startedRetrieving]getHouseName: house1
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]

通过这种方式,我可以使用特定的正则表达式解析每个字符串的值并检索值。这是我正在使用的代码:

Scanner scan = new Scanner(new File("path//to//file", "UTF-8"));
String string = "";
while(scan.hasNextLine()){
String str = scan.nextLine();
while(str.startsWith("getHouseName" && str.endsWith("rentPrice")){
string = string.append(str);
}
System.out.println(string);
}

但我得到一个空值。我怎样才能保存他文件中特定于每个房子的所有行? 非常感谢

编辑:感谢回复,我设法检索了所有内容。我怎样才能分开组?现在我有:

[04:04:04s] [startedRetrieving]getHouseName: house1
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]

[04:04:04s] [startedRetrieving]getHouseName: house2
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]

[04:04:04s] [startedRetrieving]getHouseName: house3
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]

[04:04:04s] [startedRetrieving]getHouseName: house4
[04:04:04s] [startedRetrieving]random useless text
[04:04:04s] [startedRetrieving]price (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]squaremtr (in doll) [min: 75, max:85]
[04:04:04s] [startedRetrieving]sellVal (in doll) [min: 1000, max: 1200]
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]random useless text
[04:04:05s] [startedRetrieving]rentPrice(in doll) [min: 150, max: 200]

但我想在 for 循环中单独打印所有内容。我该怎么做?

【问题讨论】:

    标签: java string file text


    【解决方案1】:
    String string = "";
    while(scan.hasNextLine()){
        String str = scan.nextLine();
        if (str.contains("getHouseName")) {
            string = "";
        }
        string = string + str + System.lineSeparator();
        if (str.contains("rentPrice")) {
            System.out.println(string);
            string = "";
        }
    }
    

    【讨论】:

    • 谢谢!但这是打印整个文件并以 RentPrice 结尾。是否可以只打印每个房屋的部分?
    • @thranduil90 string 包含一所房子的所有信息。如果您删除+ System.lineSeparator(),它将在打印输出中清晰显示。
    • 如何创建一个 for 循环以便每次都打印房子及其值?
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