Examples of java.util.HashMap

java.util.HashMap
Hash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.
This implementation provides constant-time performance for the basic operations (get and put), assuming the hash function disperses the elements properly among the buckets. Iteration over collection views requires time proportional to the "capacity" of the HashMap instance (the number of buckets) plus its size (the number of key-value mappings). Thus, it's very important not to set the initial capacity too high (or the load factor too low) if iteration performance is important.
An instance of HashMap has two parameters that affect its performance: initial capacity and load factor. The capacity is the number of buckets in the hash table, and the initial capacity is simply the capacity at the time the hash table is created. The load factor is a measure of how full the hash table is allowed to get before its capacity is automatically increased. When the number of entries in the hash table exceeds the product of the load factor and the current capacity, the hash table is rehashed (that is, internal data structures are rebuilt) so that the hash table has approximately twice the number of buckets.
As a general rule, the default load factor (.75) offers a good tradeoff between time and space costs. Higher values decrease the space overhead but increase the lookup cost (reflected in most of the operations of the HashMap class, including get and put). The expected number of entries in the map and its load factor should be taken into account when setting its initial capacity, so as to minimize the number of rehash operations. If the initial capacity is greater than the maximum number of entries divided by the load factor, no rehash operations will ever occur.
If many mappings are to be stored in a HashMap instance, creating it with a sufficiently large capacity will allow the mappings to be stored more efficiently than letting it perform automatic rehashing as needed to grow the table.
Note that this implementation is not synchronized. If multiple threads access a hash map concurrently, and at least one of the threads modifies the map structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more mappings; merely changing the value associated with a key that an instance already contains is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the map. If no such object exists, the map should be "wrapped" using the {@link Collections#synchronizedMap Collections.synchronizedMap}method. This is best done at creation time, to prevent accidental unsynchronized access to the map:
```
 Map m = Collections.synchronizedMap(new HashMap(...));
```
The iterators returned by all of this class's "collection view methods" are fail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove method, the iterator will throw a {@link ConcurrentModificationException}. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.
This class is a member of the Java Collections Framework. @param < K> the type of keys maintained by this map @param < V> the type of mapped values @author Doug Lea @author Josh Bloch @author Arthur van Hoff @author Neal Gafter @version 1.73, 03/13/07 @see Object#hashCode() @see Collection @see Map @see TreeMap @see Hashtable @since 1.2

        wrapped.putAll(t);
    }


    public synchronized void clear() {
        if (!modified) {
            wrapped = new HashMap(wrapped);
            modified = true;
        }
        wrapped.clear();
    }

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     * @param start ...
     * @param value ...
     */
    public void put(String name, Scriptable start, Object value) {
        if (map == null) {
            map = new HashMap();
        }


        if (value == null || value == Undefined.instance) {
            map.remove(name);
        } else if (value instanceof Wrapper) {

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     * @param start ...
     * @param value ...
     */
    public void put(int idx, Scriptable start, Object value) {
        if (map == null) {
            map = new HashMap();
        }


        if (value == null || value == Undefined.instance) {
            map.remove(Integer.toString(idx));
        } else if (value instanceof Wrapper) {

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    /**
     * Return the wrapped Map object.
     */
    public Object unwrap() {
        if (map == null) {
            map = new HashMap();
        }
        return map;
    }

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  getBrowserHeaders(
    String          referer )
  {
    String  headers_to_use = getBrowserHeadersToUse( null );
    
    Map  result = new HashMap();
    
    try{
    
      String header_string = new String( Base64.decode( headers_to_use ), "UTF-8" );
    
      String[]  headers = header_string.split( "\n" );
      
      for (int i=0;i<headers.length;i++ ){
      
        String  header = headers[i];
        
        int  pos = header.indexOf( ':' );
        
        if ( pos != -1 ){
          
          String  lhs = header.substring(0,pos).trim();
          String  rhs  = header.substring(pos+1).trim();
          
          if ( !( lhs.equalsIgnoreCase( "Host") || 
              lhs.equalsIgnoreCase( "Referer" ))){
            
            result.put( lhs, rhs );
          }
        }
      }
      
      if ( referer != null && referer.length() > 0){
        
        result.put( "Referer", referer );
      }
    }catch( Throwable e ){    
    }
    
    return( result );

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        // in other words, make sure our threshold for table rotation is lower
        // than that of the underlying HashMap for table rehashing.
        eachCapacity = (int) (threshold / loadFactor) + 2;
        // create tables - we'll never insert into the initial oldTable,
        // it's a dummy that will be lost on the first cache rotation.
        oldTable = new HashMap();
        newTable = createTable(eachCapacity, loadFactor);
    }

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     * @param capacity the initial capacity
     * @param loadFactor the load factor
     * @return a new Map used for internal caching
     */
    protected Map createTable(int capacity, float loadFactor) {
        return new HashMap(capacity, loadFactor);
    }

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  public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)
  {
    String dataSource = Settings.getInstance().getSiteInfo(CVUtility.getHostName(super.getServlet().getServletContext())).getDataSource();


    try {
      HashMap hm = new HashMap();


      Vector vecView = new Vector();
      Vector vecAll = new Vector();
      Vector vecSchedule = new Vector();
      Vector vecSend = new Vector();


      Collection colview = new ArrayList();
      Collection colAll = new ArrayList();
      Collection colschedule = new ArrayList();
      Collection colsend = new ArrayList();


      String typeofModule = "";


      HttpSession session = request.getSession(true);
      com.centraview.common.UserObject userobjectd = (com.centraview.common.UserObject)session.getAttribute("userobject"); //get the user object
      int individualId = userobjectd.getIndividualID();


      ListGenerator lg = ListGenerator.getListGenerator(dataSource);


      String moduleName = "";
      typeofModule = (String)request.getParameter("TYPEOFMODULE");


      if (typeofModule == null) {
        typeofModule = (String)request.getAttribute("TYPEOFMODULE");
      }
      if (typeofModule == null) {
          typeofModule = Constants.EMAILMODULE;
      }      


      if (typeofModule != null) {
        if (typeofModule.equals(Constants.ACTIVITYMODULE)) {
          moduleName = Constants.ACTIVITYMODULE;
        } else if (typeofModule.equals(Constants.EMAILMODULE)) {
          moduleName = Constants.EMAILMODULE;
        }
      }
      
      PreferenceHome prefHome = (PreferenceHome)CVUtility.getHomeObject("com.centraview.preference.PreferenceHome", "Preference");
      Preference prefRemote = (Preference)prefHome.create();
      prefRemote.setDataSource(dataSource);
      
      if (moduleName.equals(Constants.ACTIVITYMODULE)) {
      hm = prefRemote.getUserDelegation(individualId, moduleName);
        vecView = (Vector)hm.get(Constants.VIEW);
        vecSchedule = (Vector)hm.get(Constants.SCHEDULEACTIVITY);
        vecAll = (Vector)hm.get(Constants.VIEWSCHEDULEACTIVITY);
      } else if (moduleName.equals(Constants.EMAILMODULE)) {
      Vector emailVecSend = prefRemote.getEmailDelegation(individualId);
        vecView = (Vector)hm.get(Constants.VIEW);
        vecSend = emailVecSend;
        vecAll = (Vector)hm.get(Constants.VIEWSENDEMAIL);
      }


      ContactFacadeHome facadeHome = (ContactFacadeHome)CVUtility.getHomeObject("com.centraview.contact.contactfacade.ContactFacadeHome", "ContactFacade");
      ContactFacade cfremote = (ContactFacade) facadeHome.create();
      cfremote.setDataSource(dataSource);


      // get the records from the database
      Collection sqlResults = cfremote.getEmployeeListCollection(individualId);


      // now create a DisplayList out of those records
      IndividualList employeeList = new IndividualList();


      // ok, now that we have the results from the database,
      // we need to generate a DisplayList object to pass
      // to the List View code (List.jsp)
      Iterator iter = sqlResults.iterator();


      while (iter.hasNext()) {
        HashMap sqlRow = (HashMap)iter.next();


        String individualName = (String)sqlRow.get("Name");
        int individualID = ((Number)sqlRow.get("IndividualID")).intValue();


        IntMember individualIDfield = new IntMember("IndividualID", individualID, 10, "", 'T', false, 10);


        StringMember nameField = new StringMember("Name", individualName, 10, "/centraview/ViewHandler.do?" + Constants.TYPEOFCONTACT + "=" + Constants.INDIVIDUAL + "&rowId=" + individualID, 'T', true);

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      int individualId = ((UserObject)session.getAttribute("userobject")).getIndividualID();
      MarketingFacadeHome cfh = (MarketingFacadeHome)CVUtility.getHomeObject("com.centraview.marketing.marketingfacade.MarketingFacadeHome", "MarketingFacade");
      MarketingFacade remote = (MarketingFacade)cfh.create();
      remote.setDataSource(dataSource);
      int promotionid = Integer.parseInt(request.getParameter("promotionid").toString());
      HashMap mapPromotion = new HashMap();
      mapPromotion.put("PromotionID", "" + promotionid);
      remote.deletePromotion(individualId, promotionid);
    }
    catch (Exception e)
    {
      resultPage = "failure";

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  {
  
    primaryTable ="purchaseorder";
    PrimaryMemberType="PurchaseOrderID";
  
    columnMap=new HashMap();
    columnMap.put("PurchaseOrderID",new Integer(15));
    columnMap.put("Created",new Integer(25));
    columnMap.put("Creator",new Integer(50));
    columnMap.put("Entity",new Integer(50));
    columnMap.put("SubTotal",new Integer(50));

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