How to parse a table into a Java Data Structure?

Question

I've a text file with the following matrix/table:

# Matrix size is 13x13
        DEPOT   CHESHNT LIVST   CHINGFD ENFLDTN HERTFDE BSHPSFD CAMBDGE STFD    ELYY    KLYNN   STANAIR BROXBRN
DEPOT   00:00   01:00   00:28   00:02   00:40   01:00   00:02   00:05   01:00   00:30   01:00   00:31   01:00   
CHESHNT 01:00   00:00   00:38   01:00   01:03   01:27   01:02   01:05   01:56   01:21   02:00   01:25   02:00   
LIVST   00:28   00:38   00:00   00:22   00:25   00:49   01:00   01:27   01:20   01:44   01:24   00:47   01:24   
CHINGFD 00:02   01:00   00:20   00:00   00:42   01:02   00:45   01:30   00:58   01:45   01:30   00:45   01:02   
ENFLDTN 00:40   01:03   00:25   00:42   00:00   01:14   00:42   00:45   01:36   01:01   01:40   01:11   01:40   
HERTFDE 01:00   01:27   00:49   01:02   01:14   00:00   01:02   01:05   00:56   01:21   02:00   01:31   01:26   
BSHPSFD 00:02   01:02   01:00   01:00   00:42   01:02   00:00   00:30   00:54   00:47   01:02   00:33   01:02   
CAMBDGE 00:03   01:05   01:27   01:30   00:45   01:05   00:30   00:00   01:01   00:17   01:05   00:36   01:05   
STFD    01:00   01:56   01:20   00:58   01:36   00:52   00:54   01:01   00:00   01:17   01:56   01:06   00:30   
ELYY    00:22   01:30   01:44   01:45   01:10   01:30   00:47   00:17   01:26   00:00   01:30   01:01   01:30   
KLYNN   00:52   02:00   01:24   01:30   01:40   02:00   01:02   01:05   01:56   01:21   00:00   01:31   02:00   
STANAIR 00:31   01:12   00:36   00:45   00:52   01:12   00:33   00:36   01:02   00:53   01:12   00:00   01:12   
BROXBRN 01:00   02:00   01:24   01:02   01:40   01:23   01:02   01:05   00:31   01:21   02:00   01:31   00:00

Given that the structure is pretty common, is there no Java library to parse into a Java structure? Something like:

Map<String,String> matrix = MatrixParser.parse("matrix.txt"); //where the key is the concatenation of the row and column coordinates.

I can see parsing it as a CSV with OpenCSV, the separator being a space or tab instead of the comma. Nothing higher level?

There's really no reason for a "library" when String.split() pretty much covers it. — Brian Roach
– Brian Roach, Commented Nov 14, 2011 at 18:11
Once you've parsed that with OpenCSV, you'll find turning it into the data structure you're after is really trivially easy. Probably no more than a couple dozen lines of codes, tops. — G_H
– G_H, Commented Nov 14, 2011 at 18:12

Dave Newton · Accepted Answer · 2011-11-14 18:16:18Z

1

This is covered in the opencsv FAQ.

From the FAQ:

ColumnPositionMappingStrategy strat = new ColumnPositionMappingStrategy();
strat.setType(YourOrderBean.class);
String[] columns = new String[] {"name", "orderNumber", "id"}; // the fields to bind do in your JavaBean
strat.setColumnMapping(columns);

CsvToBean csv = new CsvToBean();
List list = csv.parse(strat, yourReader);

That said, it isn't that difficult anyway :)

You could do the same thing in a few lines of code using Commons BeanUtils' populate() method after splitting, line-by-line. Pseudo-code:

cols = loadColumnNamesToArray();
while (moreLines()) {
    vals = line.split
    vals.each_with_index {
        colName = cols[index]
        valMap.put(colName, val)
    }
    bean = Bean.new
    BeanUtils.populate(bean, valMap)
    beanList.add(bean)
}

answered Nov 14, 2011 at 18:16

Dave Newton

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2 Comments

simpatico Over a year ago

you see that's different from the map I'm looking for. I don't have (and don't want) a Bean.

Dave Newton Over a year ago

@simpatico Use the code w/o the bean part then. And this is less common than you think; never done it in 12 years of Java business/scientific apps. Maps of strings aren't all that useful, I almost always need actual data structures in order to manipulate them more easily, in type-safe ways.

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