extracting substring by lines

I am fairly new to programming so please bear with me. Say I have a large string such as this.

String story = "This is the first line.\开发者_如何学Pythonn"

+ "This is the second line.\n"

+ "This is the third line\n"

+ "This is the fourth line.\n"

+ "This is the fifth line.";

How would I go about extracting the first, fourth, and so on lines?

If you want to avoid creating arrays, you can use Scanner

Scanner scanner = new Scanner(story);
while(scanner.hasNextLine()) {
  System.out.println(scanner.nextLine());
}

String[] lines = story.split(System.getProperty("line.separator"));
String firstLine = lines[0];
// and so on

You can split on \n, but thus you are fixed to the line separator of *nix systems. If it happens that you have to parse on windows, splitting on \n won't work (unless of course your string is hard-coded, which defeats the whole purpose of splitting - you know which are the lines beforehand)

You can split your string into lines using the split method and then index to get the line you want:

String story =
    "This is the first line.\n" +
    "This is the second line.\n" +
    "This is the third line\n" +
    "This is the fourth line.\n" +
    "This is the fifth line."; 

String[] lines = story.split("\n");
String secondLine = lines[1];
System.out.println(secondLine);

Result:

This is the second line.

Notes:

• In Java indexing arrays starts at zero, not one. So the first line is lines[0].
• The split method takes a regular expressions as its argument.

String[] lines = story.split('\n');

String line_1 = lines[0];
String line_4 = lines[3];

or something along those lines

If the string is going to be very long, you can use a combination of a BufferedReader and a StringReader to do it one line at a time:

String story = ...;
BufferedReader reader = new BufferedReader(new StringReader(story));

while ((str = reader.readLine()) != null)  {
   if (str.length() > 0) System.out.println(str);
}

Otherwise, split the string into an Array, if it's small enough using Split:

String[] lines = story.split("\n");

You would split the string into an array and then select the array elements you want

String[] arr = story.split("\n")
arr[0] // first line
arr[3] // fourth line