line.split(",")[1] 是什么意思 [Java]？
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What does line.split(",")[1] mean [Java]?
提问by SmashCode
I came across code where i had encountered with Double.valueOf(line.split(",")[1])I am familiar with Double.valueOf()and my problem is to understand what does [1]mean in the sentence. Searched docs didn't find anything.
我遇到过Double.valueOf(line.split(",")[1])我熟悉的代码，Double.valueOf()我的问题是理解[1]句子中的含义。搜索文档没有找到任何内容。
while ((line = reader.readLine()) != null)
double crtValue = Double.valueOf(line.split(",")[1]);
回答by dryairship
It means that your lineis a String of numbers separated by commas.
eg: "12.34,45.0,67.1"
这意味着您line是一个由逗号分隔的数字字符串。
例如："12.34,45.0,67.1"
The line.split(",")returns an array of Strings.
eg: {"12.34","45.0","67.1"}
该line.split(",")返回字符串的数组。
例如：{"12.34","45.0","67.1"}
line.split(",")[1]returns the 2nd(because indexes begin at 0) item of the array.
eg: 45.0
line.split(",")[1]返回数组的第二个（因为索引从 0 开始）项。
例如：45.0
回答by dejvuth
It means lineis a string beginning with a,bwhere bis in fact a number.
这意味着line是一个以a,bwhere开头的字符串b，实际上是一个数字。
crtValueis the doublevalue of b.
crtValue是 的double值b。
回答by Buhake Sindi
Java public String[] split(String regex)
爪哇 public String[] split(String regex)
Splits this string around matches of the given regular expression.
围绕给定正则表达式的匹配项拆分此字符串。
It
它
Returns:the array of stringscomputed by splitting this string around matches of the given regular expression
返回：通过围绕给定正则表达式的匹配拆分此字符串计算出的字符串数组
So the [1]gets the 2nd item of the array found in String[].
因此，[1]获取 中找到的数组的第二项String[]。
回答by Andrew Tobilko
Your code tries to get the second doublevalue from reader.readLine().
您的代码尝试double从reader.readLine().
String numbers = "1.21,2.13,3.56,4.0,5";String[] array = numbers.split(",");split the input line by commmaString second = array[1];get the second element from the array. Java array numeration starts from0index.double crtValue = Double.valueOf(second);convertStringtodouble
String numbers = "1.21,2.13,3.56,4.0,5";String[] array = numbers.split(",");用逗号分割输入行String second = array[1];从数组中获取第二个元素。Java 数组编号从0索引开始。double crtValue = Double.valueOf(second);转换String为double
Don't forget about NumberFormatExceptionthat may be thrown if the string does not contain a parsable double.
不要忘记NumberFormatException，如果字符串不包含 parsable 可能会抛出double。
