Please find the detailed code below:

VF Code:

<apex:page controller="MyCtl" action="{!getAllItemsToSelect}">
   
   <apex:pageMessages />
   
   <apex:form>
   	<apex:outputPanel id="pnlInput">
        <apex:pageBlock >
            <apex:pageBlockButtons location="bottom">
        	<apex:commandButton action="{!processSelection}" value="Display" rerender="pnlPoller"/>
            </apex:pageBlockButtons>
        	
            <apex:outputLabel value="Select Item:"/>
            <apex:selectList id="selectObject" value="{!SelectedNameList}" multiselect="true">
                <apex:selectOptions value="{!ItemList}"/>
            </apex:selectList>
            
            <p>
            <apex:outputLabel value="Select Category:" for="rdCategory"/>
   	    <apex:selectRadio id="rdCategory" value="{!SelectedCategory}">
      		<apex:selectOptions value="{!CategoryLblList}"/>
      	    </apex:selectRadio></p>
        </apex:pageBlock>
      </apex:outputPanel>
      
      <apex:outputPanel id="pnlPoller">
      		<apex:actionPoller action="{!getAllFieldValues}" enabled="{!IsPollerEnabled}" rerender="pnlDisplayAllFieldDetails" interval="5" status="tableStatus"/>
      </apex:outputPanel>
      
   </apex:form>
   
   <div align="center">
   	  <apex:actionStatus id="tableStatus">
	    <apex:facet name="start" >                
		<center> PROCESSING...</center>                
	    </apex:facet> 
	    <apex:facet name="stop"/>            
	  </apex:actionStatus>
   </div>
   
   <apex:outputPanel id="pnlDisplayAllDetails">
       <apex:dataTable id="tblDisplay" value="{!DisplayItemResultList}" var="ft" rendered="{!IF(IsTableVisible == True, True, False)}">    
            <apex:column headerValue="FIELD1">
                <apex:outputText value="{!ft.Field1}"/>
            </apex:column>
             
            <apex:column headerValue="FIELD2">
                <apex:outputText value="{!ft.Field2}"/>
            </apex:column>
       </apex:dataTable>
   </apex:outputPanel>
   
</apex:page>

 Controller Code:

public class MyCtl
{								 
  private List<Selectoption> ItemList= new List<Selectoption>();			    private List<Selectoption> CategoryLblList = new List<Selectoption>();
 private String SelectedCategory = 'all'; 						 private static String[] SelectedNameList = new String[]{};				  private static List<MyCustomType> ItemResultList = new List<MyCustomType>();	
		
private static List<MyCustomType> DisplayItemResultList;				private Map<Integer, List<String>> ProcessingBatchMap = new    Map<Integer,List<String>>();			
	 
	 //Constructor
	 public MyCtl()
	 {	
	   MapKey = -1;
	   IsPollerEnabled = false;
	   IsTableVisible = false;
	 }
	 
	 //Custom Type
	 public class MyCustomType
	 {
	   public MyCustomType(String pField1, String pField2)
	   {
	     Field1 = pField1;
	     Field2 = pField2;
	   }
	 	
	   public String Field1 {get; set;}
	   public String Field2 {get; set;}
	 }
	 	 
	 //ItemResultList
	 public List<MyCustomType> getItemResultList ()
	 { return ItemResultList; }
	 
	 //DisplayItemResultList
	 public List<MyCustomType> getDisplayItemResultList()
	 { return DisplaySFDCFieldList; }
	 
	 public void setDisplayItemResultList(List<MyCustomType> pDisplayItemResultList)
	 { 
	 	DisplayItemResultList = new List<MyCustomType>();
	 	DisplayItemResultList.addAll(pDisplayItemResultList); 
	 }
	 
	 //ItemList
	 public List<SelectOption> getItemList()
	 { 
	 	this.getAllItemsToSelect();
	 	return ItemList;
	 }
	 
	 //SelectedNameList
	 public List<String> getSelectedNameList()
	 { return SelectedNameList; }
	 
	 public void setSelectedNameList(String[] pSelectedNameList)
	 { 
	 	//Clear any existing selected options if any
	 	if(!SelectedNameList.isEmpty())
	 		SelectedNameList.clear(); 
	 	
	 	//Identify the list of selected object names
	 	for(String strSelectedName : pSelectedNameList) 
	 	{ 
	 	  SelectedNameList.add(strSelectedName);	
	 	}
	 }
	 	 
	 //SelectedCategory
	 public String getSelectedCategory ()
	 { return SelectedCategory; }	 	

	 public void setSelectedCategory (String pSelectedCategory)
	 { SelectedCategory = pSelectedCategory);}
	 
	 //CategoryLblList 
	 public List<Selectoption> getCategoryLblList()
	 {
	 	if(CategoryLblList.isEmpty())
	 	{
		  CategoryLblList.add(new Selectoption('all', 'All'));
		  CategoryLblList.add(new Selectoption('new', 'New'));
		  CategoryLblList.add(new Selectoption('old', 'Old'));
	 	}
	 	return CategoryLblList;
	 }
	 
	 public Integer MapKey{get; set;}						
	 public Boolean IsPollerEnabled{get; set;} 				
	 public Boolean IsTableVisible{get; set;}			
	 public Integer BatchMapSize {get; set;} 
	
	 //METHODS
	 public void getAllItemsToSelect()
	 {
   	    /* Query and get values to select*/
	    for(String strItemName : ItemNameList)
	    ItemList.add(strItemName)
	 }
	 
	 //Executes when the View On Screen is clicked and enables the action poller
	 public void processSelection()
	 {
	 	this.createProcessingBatches();	//Create batches of the selected names
	 	if(MapKey == -1)
	 		this.MapKey = 1;
	 	if(!SFDCFieldList.isEmpty())	//Clear the old values 
	 		SFDCFieldList.clear();
		this.IsPollerEnabled = true;	//Activate the poller
	 }
	 
	 //Divides the selected names into batch of 25 elements each and stores in a Map 
	 public void createProcessingBatches()
	 {
 	   Integer intCount = 1;
	   List<String> BatchList = new List<String>();
	   
	   //Clear the old elements to store new elements
	   ProcessingBatchMap.clear();
	   for(Integer intIndex = 0; intIndex < (SelectedNameList.size(); intIndex++)
	   {
	   	 BatchList.add((SelectedNameList.get(intIndex));
	   	 if((Math.mod(BatchList.size(), 25) == 0) || intIndex == (SelectedNameList.size() - 1)	
	 	 {
	 	 	ProcessingBatchMap.put(intCount, BatchList);
	 	 	++intCount;		//increment the count
	 	 	BatchList = new List<String>();	//to store elements for new batch
	 	 } 	
	   }
	   BatchMapSize = ProcessingBatchMap.size();
	 }
	 

	 public void getAllFieldValues()
	 {
	   /* Fetch List<FieldValues>*/
           for(objFld : List<FieldValues>)
           { ItemResultList.add(new MyCustomType(objFld.Field1, objFld.Field2));}

	   this.updateMapIndex();
	 }
	 
	 private void updateMapIndex()
	 {
	 	if((this.MapKey + 1) > ProcessingBatchMap.size()){
	 	  IsPollerEnabled = false;
	 	  IsTableVisible = true;
	 	  MapKey = 1;
	 	  DisplayItemResultList = ItemResultList;
                }
	 	else
	 	  ++MapKey;
	 }
	 
}//MyCtl Ends

   This might help !!