Sorting hash map on text.

[Former Member]

hi,

I am using a hash map which is showing the data with out sorting.

I am able to sort it using the tree map, but the code is sorting according to the id or key and i want to display the data by sorting according to the Text.

Regards,

Sanjyoti.

[Former Member · Accepted solution]

Hi Sanjyoti,

My team have some code regarding this that they have used for some functionality, hope this help.

========Sort based on the keys ========
Map yourMap= new HashMap();
// put some tuples in yourMap ...
Map sortedMap = new TreeMap(yourMap);

=====To sort only the keys : ========
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

    Map<String,java.io.File> Val = new HashMap<String,java.io.File>();
    Val.put("Roshan", new java.io.File("Roshan.gif"));
    Val.put("Sandy", new java.io.File("Sandy.gif"));
    Val.put("Dhiraj", new java.io.File("Dhiraj.gif"));
    Val.put("Laxmi", new java.io.File("Laxmi.gif"));
    Val.put("Vipul", new java.io.File("Vipul.gif"));
    Val.put("Shashank", new java.io.File("SHASHANK.gif"));

    SortedSet<String> sortedset= new TreeSet<String>(Val.keySet());

    Iterator<String> it = sortedset.iterator();

    while (it.hasNext()) {
      System.out.println (it.next());
    }
  
...


--------------------------------------------------------------------------------
==========Sort based on the values ======
HashMap yourMap = new HashMap();
// put some tuples in yourMap ...

// to hold the result
HashMap map = new LinkedHashMap();


List yourMapKeys = new ArrayList(yourMap.keySet());
List yourMapValues = new ArrayList(yourMap.values());
TreeSet sortedSet = new TreeSet(yourMapValues);
Object[] sortedArray = sortedSet.toArray();
int size = sortedArray.length;

for (int i=0; i<size; i++) {
   map.put
      (yourMapKeys.get(yourMapValues.indexOf(sortedArray<i>)),
       sortedArray<i>);
}

=======To iterate your new Sorted Map ===
Set ref = map.keySet();
Iterator it = ref.iterator();

while (it.hasNext()) {
  String file = (String)it.next();

Regards,

Roshan

[Former Member · Accepted solution]

hey,

thanks to both of u...

good to see ur replies.

but check kar ke.... points dungi :D.

Regards,

Sanjyoti.

[Former Member]

Hello Sanjyoti,

Following example demonstrate getting a List of values out of a Map where you'd like the contents to be ordered by Value (not Key).

 
import java.text.MessageFormat;  
import java.util.Collections;  
import java.util.Comparator;  
import java.util.HashMap;  
import java.util.LinkedList;  
import java.util.List;  
import java.util.Map;  
import java.util.Map.Entry;  
  
import org.apache.log4j.Logger;  
import org.testng.annotations.BeforeClass;  
import org.testng.annotations.Test;  
  
/** 
 * Sorting a Map<String,Long> by Values 
 *  
 * @author ableasdale 
 *  
 */  
public class TestOrderingMapItems {  
  
 private static final Logger LOG = Logger  
   .getLogger(TestOrderingMapItems.class);  
 private Map<String, Long> map;  
  
 @BeforeClass  
 public void setUpOnce() throws Exception {  
  LOG.info("Set up");  
  map = new HashMap<String, Long>();  
  map.put("A", 5L);  
  map.put("B", 4L);  
  map.put("C", 10L);  
  map.put("D", 6L);  
 }  
  
 @Test  
 public void getItemsByKeyInOrder() throws Exception {  
  List<Map.Entry<String, Long>> resultList = new LinkedList<Map.Entry<String, Long>>(  
    map.entrySet());  
  
  Collections.sort(resultList, new Comparator<Object>() {  
   public int compare(Object o1, Object o2) {  
    // Switch o2 and o1 to order from lowest to highest  
    return ((Comparable<Object>) ((Map.Entry<?, ?>) (o2))  
      .getValue()).compareTo(((Map.Entry<?, ?>) (o1))  
      .getValue());  
  
   }  
  });  
  
  LOG.info("Ordered list as follows:");  
  for (Object e : resultList) {  
   LOG.info(MessageFormat.format("{0} | {1}", ((Entry<?, ?>) e).getKey(), ((Entry<?, ?>) e).getValue()));  
  }  
 }  
}  

Warm Regards

Upendra Agarwal

Edited by: Upendra Agrawal on Feb 16, 2010 10:23 AM

[Former Member]

Hi,

thanks Upendra.

i am not able to fill the code porperly would u pls help.

Regards,

Sanjyoti.

[Former Member]

Dear Sanjyoti,

As suggessted by roshan...may, this one will help..

HashMap yourMap = new HashMap();

// put some tuples in yourMap .....
yourMap.put("TextA",5);
yourMap.put("TextC",4);
yourMap.put("TextD",3);
yourMap.put("TextB",2);
yourMap.put("TextE",1);


List yourMapKeys = new ArrayList(yourMap.keySet());
List yourMapValues = new ArrayList(yourMap.values());
TreeSet sortedSet = new TreeSet(yourMapValues);
Object[] sortedArray = sortedSet.toArray();
int size = sortedArray.length;


// to hold the result....
HashMap map = new LinkedHashMap();

//ascending sort......
for (int i=0; i<size; i++) {
   map.put
      (yourMapKeys.get(yourMapValues.indexOf(sortedArray<i>)),
       sortedArray<i>);
}

// iterate your new sorted map
Set ref = map.keySet();
Iterator it = ref.iterator();

while (it.hasNext()) {
  String file = (String)it.next();
} 

Warm Regards,

Upendra Agrawal