CODEWITHSUNDEEP
javatext-parsingline-processing
user597608
user597608

Reputation: 387

Parsing in Java with C style?

I am new to java text parsing and I'm wondering what is the best way to parse a file when the format of each line is known.

I have a file that has the following format for each line:

Int;String,double;String,double;String,double;String,double;String,double

Note how the String,double act as a pair separated by a comma and each pair is separated by a semicolon.

A few examples:

1;art,0.1;computer,0.5;programming,0.6;java,0.7;unix,0.3
2;291,0.8;database,0.6;computer,0.2;java,0.9;undegraduate,0.7
3;coffee,0.5;colombia,0.2;java,0.1;export,0.4;import,0.5

I'm using the following code to read each line:

public static void main(String args[]) {
    try {
        // Open the file that is the first
        // command line parameter
        FileInputStream fstream = new FileInputStream("textfile.txt");
        // Get the object of DataInputStream
        DataInputStream in = new DataInputStream(fstream);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String strLine;
        // Read File Line By Line
        while ((strLine = br.readLine()) != null) {
            // Print the content on the console             
            System.out.println(strLine);
        }
        // Close the input stream
        in.close();
    } catch (Exception e) {// Catch exception if any
        System.err.println("Error: " + e.getMessage());
    }   
 }

Thanks in advance :)

Upvotes: 0

Views: 576

Answers (3)

r0ast3d
r0ast3d

Reputation: 2635

You can provide a pattern and use the Scanner

String input = "fish1-1 fish2-2";
java.util.Scanner s = new java.util.Scanner(input);
s.findInLine("(\\d+)");
java.util.regex.MatchResult result = s.match();
for (int i=1; i<=result.groupCount(); i++)
    System.out.println(result.group(i));
s.close();

Upvotes: 0

&#211;scar L&#243;pez
&#211;scar L&#243;pez

Reputation: 236014

You could use the Scanner class, for starters:

A simple text scanner which can parse primitive types and strings using regular expressions.

Upvotes: 4

Edwin Buck
Edwin Buck

Reputation: 70909

If you are truly trying to do "C" style parsing, where is the buffer which contains the characters being accumulated for the "next" field? Where is the check that sees if the field separator was read, and where is the code that flushes the current field into the correct data structure once the end of line / field separator is read?

A character by character read loop in Java looks like

int readChar = 0;
while ((readChar = in.read()) != -1) {
   // do something with the new readChar.
}

Upvotes: 0

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