i have a text file with contents:
26/09/2013,16:04:40 2412 -928.0
25/09/2013,14:24:30 2412 914.0
The file above contains a date, time an integer and a double on each line
I have made a class to contain the data once it is read in:
public class Entry{
public String date, time;
public int integerNumber;
public double doubleNumber;
public Entry(String d, String t, int n1, double n2){
this.date=d;
this.time=t;
this.integerNumber=n1;
this.doubleNumber=n2;
}
}
What is the best way to read the above file into an Entry[] array where each element in the array is the data from each line?
EDIT : My current attempt involves reading each line as a String and creating substrings for the various pieces of data eg String date=line.substring(0,10);
This works fine for now but when i get to the integer for example, it wont necessarily be a 4 digit number. This leaves me stuck as i don't know how to read a number of arbitrary size.
You can use a regular expression to read the text file.
For example,
String line = "001 John Smith";
String regex = "(\\d)+ (\\w)+ (\\w)+";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(line);
while(matcher.find()){
String [] group = matcher.group().split("\\s");
System.out.println("First Name "+group[1]);
System.out.println("Last Name " +group[2]);
}
Well, if you can guarantee that all your lines in the file you're reading have the following format
<date>,<time> <integer> <double>
You could read it like this
String foo = "25/09/2013,14:24:30 2412 914.0";
String delims = "[, ]+";
String[] tokens = foo.split(delims);
String d = tokens[0]; // d would contain the string '25/09/2013'
String t = tokens[1]; // t would contain the string '14:24:30'
int n1 = Integer.parseInt(tokens[2]); // n1 would contain the integer 2412
double n2 = Double.parseDouble(tokens[3]); // n2 would contain the double 914.0
You can use Scanner for this.
It has constructor which takes File
and also has next()
, nextInt()
, nextDouble()
methods to read String,int,double
respectively.
For sample code reference link : http://www.cs.utexas.edu/users/ndale/Scanner.html
Could be done by using Use Apache Commons FileUtils
File file = new File("/yourfile.txt");
List<String> lines = FileUtils.readLines(file, null);
List<Entry> entries = new ArrayList<Entry>();
for (String line : lines) {
//line == 26/09/2013,16:04:40 2412 -928.0
Entry entry = createEntry(line); // parse string and create a Entry...
entries.add(entry);
}
// Warning, not safe and not pretty...
private static Entry createEntry(String line) {
String[] parts = line.split(" ");
String[] datePart = parts[0].split(",");
return new Entry(datePart[0],
datePart[1],
Integer.valueOf(parts[1]),
Double.valueOf(parts[2])
);
}
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