What does line.split(",")[1] mean [Java]?

Question

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.

while ((line = reader.readLine()) != null)
                double crtValue = Double.valueOf(line.split(",")[1]);

https://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html — Reimeus, Apr 04 '16 at 13:26
`line#split` returns an array, `[1]` acceses the second element of the returned array. — SomeJavaGuy, Apr 04 '16 at 13:27
@KevinEsche uhm, no, the 2nd element; unless you mean element at index 0 to be the 0th element — fge, Apr 04 '16 at 13:28

score 14 · Accepted Answer · answered Apr 04 '16 at 13:27

It means that your line is a String of numbers separated by commas.
eg: "12.34,45.0,67.1"

The line.split(",") returns an array of Strings.
eg: {"12.34","45.0","67.1"}

line.split(",")[1] returns the 2nd(because indexes begin at 0) item of the array.
eg: 45.0

score 3 · Answer 2 · answered Apr 04 '16 at 13:28

3

It means line is a string beginning with a,b where b is in fact a number.

crtValue is the double value of b.

answered Apr 04 '16 at 13:28

dejvuth

6,986
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score 3 · Answer 3 · answered Apr 04 '16 at 13:29

Java public String[] split(String regex)

Splits this string around matches of the given regular expression.

It

Returns: the array of strings computed by splitting this string around matches of the given regular expression

So the [1] gets the 2nd item of the array found in String[].

Andrew Tobilko · Answer 4 · 2016-04-04T13:42:47.177

Your code tries to get the second double value from reader.readLine().

String numbers = "1.21,2.13,3.56,4.0,5";
String[] array = numbers.split(","); split the input line by commma
String second = array[1]; get the second element from the array. Java array numeration starts from 0 index.
double crtValue = Double.valueOf(second); convert String to double

Don't forget about NumberFormatException that may be thrown if the string does not contain a parsable double.

What does line.split(",")[1] mean [Java]?

4 Answers4