如何在Java中的特定詞后找到特定值？

Question

我從BufferedReader獲得了文本，我需要在特定字符串中獲取特定值。

這是文本：

    aimtolerance = 1024;
    model = Araarrow;
    name = Bow and Arrows;
    range = 450;
    reloadtime = 3;
    soundhitclass = arrow;
    type = Ballistic;
    waterexplosionclass = small water explosion;
    weaponvelocity = 750;

        default = 213;
        fort = 0.25;
        factory = 0.25;
        stalwart = 0.25;
        mechanical = 0.5;
        naval = 0.5;

我需要獲取默認=和;之間的確切數字。

就是“ 213”

Answer 1

像這樣...

String line;
while ((line = reader.readLine())!=null) {
   int ind = line.indexOf("default =");
   if (ind >= 0) {
      String yourValue = line.substring(ind+"default =".length(), line.length()-1).trim(); // -1 to remove de ";"
      ............
   }
}

Answer 2

如果只關心最終結果，即從“ =”分隔值文本文件中獲取內容，您可能會發現內置的Properties對象有用嗎？

http://docs.oracle.com/javase/6/docs/api/java/util/Properties.html

這可以滿足您的大部分需求。 當然，如果您特別想手動執行此操作，則可能不是正確的選擇。

Answer 3

分割字符串的“默認值=”，然后使用的indexOf找到的第一次出現“;”。 做一個從0到索引的子字符串，您便擁有了自己的價值。

參見http://docs.oracle.com/javase/7/docs/api/java/lang/String.html

Answer 4

使用正則表達式：

private static final Pattern DEFAULT_VALUE_PATTERN
        = Pattern.compile("default = (.*?);");

private String extractDefaultValueFrom(String text) {
    Matcher matcher = DEFAULT_VALUE_PATTERN.matcher(text);
    if (!matcher.find()) {
        throw new RuntimeException("Failed to find default value in text");
    }
    return matcher.group(1);
}

Answer 5

您可以使用Properties類來加載字符串並從中找到任何值

String readString = "aimtolerance = 1024;\r\n" + 
"model = Araarrow;\r\n" + 
"name = Bow and Arrows;\r\n" + 
"range = 450;\r\n" + 
"reloadtime = 3;\r\n" + 
"soundhitclass = arrow;\r\n" + 
"type = Ballistic;\r\n" + 
"waterexplosionclass = small water explosion;\r\n" + 
"weaponvelocity = 750;\r\n" + 
"default = 213;\r\n" + 
"fort = 0.25;\r\n" + 
"factory = 0.25;\r\n" + 
"stalwart = 0.25;\r\n" + 
"mechanical = 0.5;\r\n" + 
"naval = 0.5;\r\n";
readString = readString.replaceAll(";", "");
Properties properties = new Properties();

System.out.println(properties);
try {
    properties.load(new StringReader(readString));
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
System.out.println(properties);

String requiredPropertyValue = properties.getProperty("default");
System.out.println("requiredPropertyValue : "+requiredPropertyValue);