Bill Lampos

This is another way to sort a HashMap. This way is more useful as it sorts the HashMap and keeps the duplicate values as well.

public LinkedHashMap sortHashMapByValuesD(HashMap passedMap) {
    List mapKeys = new ArrayList(passedMap.keySet());
    List mapValues = new ArrayList(passedMap.values());
    Collections.sort(mapValues);
    Collections.sort(mapKeys);
        
    LinkedHashMap sortedMap = 
        new LinkedHashMap();
    
    Iterator valueIt = mapValues.iterator();
    while (valueIt.hasNext()) {
        Object val = valueIt.next();
        Iterator keyIt = mapKeys.iterator();
        
        while (keyIt.hasNext()) {
            Object key = keyIt.next();
            String comp1 = passedMap.get(key).toString();
            String comp2 = val.toString();
            
            if (comp1.equals(comp2)){
                passedMap.remove(key);
                mapKeys.remove(key);
                sortedMap.put((String)key, (Double)val);
                break;
            }

        }

    }
    return sortedMap;
}

If you want to sort a HashMap and keep the duplicate entries then see the solution in this article. Otherwise, read this article!

TASK
I want to sort my HashMap entries depending on the value of each one of them. I do not care about duplicate entries - duplicate entries are ignored by using this method. My HashMap is named as unSorted and it has values. In other words, it is defined as:

HashMap<String, Double> unSorted = new HashMap<String, Double>();

Now we put some sample entries in the HashMap, just to have something to order.

unSorted.put("Bristol", 23.45);
unSorted.put("London", 345.122);
unSorted.put("Manchester", 12.3);
unSorted.put("Edinburgh", 11.4); 

Then we write a method that is able to take a HashMap as an input and after doing some crazy staff, it outputs the same HashMap but with its values sorted (ascending).

SOLUTION
This is the source code of the method:

private HashMap<String, Double> sortHashMap(HashMap<String, Double> input){
    Map<String, Double> tempMap = new HashMap<String, Double>();
    for (String wsState : input.keySet()){
        tempMap.put(wsState,input.get(wsState));
    }

    List<String> mapKeys = new ArrayList<String>(tempMap.keySet());
    List<Double> mapValues = new ArrayList<Double>(tempMap.values());
    HashMap<String, Double> sortedMap = new LinkedHashMap<String, Double>();
    TreeSet<Double> sortedSet = new TreeSet<Double>(mapValues);
    Object[] sortedArray = sortedSet.toArray();
    int size = sortedArray.length;
    for (int i=0; i<size; i++){
        sortedMap.put(mapKeys.get(mapValues.indexOf(sortedArray[i])), 
                      (Double)sortedArray[i]);
    }
    return sortedMap;
}

Now, to retrieve a HashMap with sorted values, you just have to use(!) the method above.

HashMap<String, Double> sorted = new HashMap<String, Double>();
sorted = sortHashMap(unSorted);

Do you want to implement a cron job for a JAR file? With high probability you will not even care about this, but since it is really something easy I would like to share this information with you!

You do not have to do something incredible, just use the Windows Task Scheduler. You will realise that Windows Task Scheduler is able to schedule the execution of (executable in Windows) files at any time and with many (interesting) preferences (it is a nice but somewhat hidden application of Windows).

Since a JAR file is not a Windows executable file, all you need to do is:

• Open Windows Task Scheduler (in Vista it is located under system32 folder OR you may find it in Start >> Accessories >> System Tools.
• Create a New Task.
• After editing your scheduling parameters (Triggers), go to Actions and choose Start a Program Action.
• Set script to

  C:\Program Files\Java\jdk1.6.0_02\bin\java.exe

  or wherever your java.exe file is located in.
• Set add arguments option to something like

  -jar C:\Users\YourUsername\PathToJARFile\JARfile.jar

  .

  You are ready to go!