can anyone help me to display all the standard objects in one picklist and when i select any one object, then all the records in that objects have to display.

<apex:page controller="ClassName">
    <apex:form >
        <apex:selectList value="{!choosenObject}" size="1">
              <apex:selectoptions value="{!objects}"/>
        </apex:selectList>
<br/>
       <apex:commandbutton value="Query" action="{!queryMe}" rerender="output"/>
         <apex:dataList id="output" value="{!records}" var="r">
         {!r}
        </apex:dataList>
    </apex:form>
</apex:page>

public class ClassName{
        public List<SelectOption> objects {get; set;}
        public List<SObject> records {get; set;}
        public string choosenObject {get; set;}
        public ClassName(){
               objects = new List<SelectOption>();
               records = new List<SObject>();
               Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe(); 
               List<String> objectList = new List<String>();
               objectList.addAll(gd.keyset());
               Schema.DescribeSobjectResult[] results = Schema.describeSObjects(objectList );
               for(Schema.DescribeSobjectResult res : results) { 
                    if( ! res.isCustom()) 
                          objects.add(new selectOption(res.getName() ,res.getLabel())); 
               }
        }
        public void queryMe(){
               if(string.isNotBlank(choosenObject))
               records = database.query('select Id, Name from '+choosenObject);
               //you may need to remove Name field for some objects
        }
}