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PaddyW
Tux's lil' helper
Joined: 19 Jun 2006
Posts: 113
Location: germany/nrw/neuss
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 Posted: Thu Apr 15, 2010 9:39 am Post subject: [Help] Java: Save many strings to one 2d string array. How? |
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Hey guys,
I'm pretty new to Java. Sorry for the bad thread name, but I'm just so helpless, I can't even find a proper name for my problem.
My problem is:
I'm reading a file, line by line. That's no problem. The thing is, the file contains a section where it says:
header
begin
this is gentoo linux
i am
paddyw noob
...
end
My code reads each line as a string-array. the delimiter is a whitespace. so 'header' is a string-array with length 1, and 'this is gentoo linux' is a string-array with length 4 and so on.
I want to create a 2D string array, where it saves each string.
array[0][0] = "header"
array[1][0] = "begin"
array[2][0] = "this"
array[2][1] = "is"
...
and so on. The problem is: How can I do that? All my strings have different lengths...
A friend of mine told me I should look up ArrayLists, because with ArrayCopy it seems pretty confusing. But it's hard to understand that without a proper example code or tutorial. Can someone help me please?
Thank you very much! If this is over I'm going to party!!!!!! |
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Dr.Willy
Guru
Joined: 15 Jul 2007
Posts: 547
Location: NRW, Germany
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| Posted: Thu Apr 15, 2010 9:48 am Post subject: |
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| Code: | ArrayList lines = new ArrayList();
String line;
while((line = reader.readLine()) != null) {
lines.add(Arrays.asList(line.split(" ")));
} |
..from the top of my head. Convert to generics if you feel like it  |
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PaddyW
Tux's lil' helper
Joined: 19 Jun 2006
Posts: 113
Location: germany/nrw/neuss
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| Posted: Thu Apr 15, 2010 10:05 am Post subject: |
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Thanks for the fast reply!!!
So, I have an object of type ArrayList. But what if I want to return an object of type String[][]? |
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HoloDoc
Tux's lil' helper
Joined: 20 Jun 2006
Posts: 76
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| Posted: Thu Apr 15, 2010 11:51 am Post subject: |
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Hey PeddyW!
here is my Solution for your 2 dimensional String Problem:
| Code: | public static void main(String[] args) {
ArrayList<String[]> lines = new ArrayList<String[]>();
String[] inputArray = new String[1];
inputArray[0] = "header";
lines.add(inputArray);
inputArray = new String[1];
inputArray[0] = "begin";
lines.add(inputArray);
inputArray = new String[2];
inputArray[0] = "this";
inputArray[1] = "this";
lines.add(inputArray);
String[][] sOut = ArrayListToPaddyWsGreat2DimensionalExcellentArray(lines);
}
public static String[][] ArrayListToPaddyWsGreat2DimensionalExcellentArray (ArrayList<String[]> alInput){
String[][] out =new String[alInput.size()][];
for(int i = 0; i < alInput.size(); i++){
out[i] = alInput.get(i);
}
return out;
} |
have fun!
Holodoc
ps: no violation against doves  |
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Voltago
Advocate
Joined: 02 Sep 2003
Posts: 2593
Location: userland
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| Posted: Thu Apr 15, 2010 12:02 pm Post subject: |
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I'd try (similar to Dr. Willy)
| Code: | BufferedReader br = new BufferedReader(new FileReader("myfile.txt"));
ArrayList<String[]> lines = new ArrayList();
String line;
while((line=br.readLine())!=null)
lines.add(line.split("\\s*")); //splits each line around whitespace characters and adds to lines
String[][] linesArray = (String[][]) lines.toArray(); |
Note the last line. Problem with using a String[][] object directly is that you don't know how many lines you will need, so it's more convenient to use something dynamically growing like ArrayList. |
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