Sorting the values in the treemap

Question

I read a text file and stored in a Tree map with each key having multiple values.Like,

key: A1BG values: G5730 A4527 E3732 B0166

key: BCA3 values: C1478 A4172 D8974 B1432 E2147

key: DB8C values: N0124 K7414 X9851

Since it is tree map I got all the keys sorted.Now,I want to sort all those values corresponding to the key.And get o/p As,

key: A1BG values: A4527 B0166 E3732 G5730

key: BCA3 values: A4172 B1432 C1478 D8974 E2147

key: DB8C values: K7414 N0124 X9851

Iam new to java.Can anyone help over this. Here is my code

BufferedReader reader =  new BufferedReader(new FileReader("E:\\book\\datasone.txt"));
Map<String, String> map = new TreeMap<String,String>();
String currentLine;
while ((currentLine = reader.readLine()) != null) 
{
  String[] pair  = currentLine.split("\\s+");
  key = pair[0];
  value = pair[1];
  if(map.containsKey(key))
  {
    value +=  map.get(key);
  }
  else
  {
    map.put(key,value);    
  }
}
for (String name: map.keySet())
{
  String key =name.toString();
  String value = map.get(name).toString();  
  System.out.println(key + " " + value+ " ");  
}

possible duplicate of [How to sort a treemap based on its values?](http://stackoverflow.com/questions/1448369/how-to-sort-a-treemap-based-on-its-values) — smonff, Aug 20 '13 at 02:32

BevynQ · Answer 1 · 2013-08-20T03:32:07.233

If there are no duplicate values then you could store the values as a TreeSet

public class TestMap {

    public static void main(String[] args) {

        List<String> lines = new ArrayList();
        lines.add("A1BG G5730");
        lines.add("A1BG A4527");
        lines.add("A1BG E3732");
        lines.add("A1BG B0166");
        lines.add("BCA3 C1478");
        lines.add("BCA3 A4172");
        lines.add("BCA3 D8974");
        lines.add("BCA3 B1432");
        lines.add("BCA3 E2147");
        lines.add("DB8C N0124");
        lines.add("DB8C K7414");
        lines.add("DB8C X9851");

        Map<String, Set<String>> map = new TreeMap<String,Set<String>>();
        for(String currentLine : lines){
            String[] pair  = currentLine.split("\\s+");
            String key = pair[0];
            String value = pair[1];
            if(!map.containsKey(key)){
                Set<String> set = new TreeSet<String>();
                map.put(key,set);
            }
            map.get(key).add(value);
        }
        for (String name: map.keySet())
        {
            String key =name.toString();
            System.out.print(key);
            for (String value : map.get(name)){
                System.out.print(" " + value);
            }
            System.out.println();
        }
    }
}

output

A1BG A4527 B0166 E3732 G5730
BCA3 A4172 B1432 C1478 D8974 E2147
DB8C K7414 N0124 X9851

It stores the garbage data into values. Can u please help me to figure this out.. — trx, Aug 20 '13 at 03:22

MadProgrammer · Answer 2 · 2013-08-20T03:12:24.013

Since all the values are stored in the Map as Strings separated by space, you will have to post-process the Map (ie, process it after you've finished reading it)...

Basically, I would extract each value, split them on the space character into a String[] and use Arrays#sort to sort them. Reproduce the String value and set it back as the value for the specified key.

For example...

for (String name: map.keySet())
{
  String key = name.toString();
  String value = map.get(name).toString();  
  String[] parts = value.split(" ");
  Arrays.sort(parts);
  StringBuilder sb = new StringBuilder(value.length());
  for (String part : parts) {
    if (sb.length() != 0) {
        sb.append(" ");
    }
    sb.append(part);
  }
  map.put(key, value);
}

It might be easier to start with a SortedMap<String, SortedSet<String>>. That way you could sort the values as your are reading the file, but you'd have to still post process the file to generate the SortedMap<String, String> map you are using.

This, of course, assumes that there are no duplicates values ;)

If there are duplicate values, you could use SortedMap<String, List<String>> instead. But you would need to post process the map after you finish loading it, using something Collections.sort(List) to sort the List associated with each key in the Map and produce the String value you want...

SortedSet example

BufferedReader reader = null;
try {
    reader = new BufferedReader(new FileReader("datasone.txt"));
    Map<String, SortedSet<String>> map = new TreeMap<String, SortedSet<String>>();
    String currentLine;
    while ((currentLine = reader.readLine()) != null) {
        String[] pair = currentLine.split("\\s+");
        String key = pair[0];
        String value = pair[1];
        SortedSet<String> set = map.get(key);
        if (set == null) {
            set = new TreeSet<String>();
            map.put(key, set);
        }
        set.add(value);
    }
    for (String name : map.keySet()) {
        String key = name.toString();
        SortedSet<String> set = map.get(key);
        StringBuilder sb = new StringBuilder(128);
        sb.append(key).append(":");
        for (String value : set) {
            sb.append(" ").append(value);
        }
        System.out.println(sb.toString());
    }
} catch (IOException exp) {
    exp.printStackTrace();
} finally {
    try {
        reader.close();
    } catch (Exception e) {
    }
}

Which reads...

A1BG G5730 
A1BG A4527 
A1BG E3732 
A1BG B0166
BCA3 C1478 
BCA3 A4172 
BCA3 D8974 
BCA3 B1432 
BCA3 E2147
DB8C N0124 
DB8C K7414 
DB8C X9851

And generates...

A1BG: A4527 B0166 E3732 G5730
BCA3: A4172 B1432 C1478 D8974 E2147
DB8C: K7414 N0124 X9851

Never seen SortedMap, perhaps you mean SortedSet or List? – Taylor Aug 20 '13 at 02:09 — Taylor, Aug 20 '13 at 02:09
@Taylor Ahh, back to bed I think :P – MadProgrammer Aug 20 '13 at 02:11 — MadProgrammer, Aug 20 '13 at 02:11

Sorting the values in the treemap

2 Answers2