Visualforce Controller for Multiple Tasks

Question

I have the controller below for a Visualforce page set up on the Contact record as a Detail Page button. The purpose is to allow users to set up multiple tasks at once, but also pre-populate the WhoID, OwnerId, and WhatId for the tasks.

The problem I am running into is when I click the Add Another RDA button on the VF page, it creates an exact clone of the previous task and if I change a value, it changes for all the tasks. How can I make it so that each task is individual of one another, but still able to be created at the same time?

CONTROLLER:

public with sharing class RDATasks{

    public list<Task> listTask{get;set;}

    private final Contact con;
    public RDATasks(ApexPages.StandardController myController){
        listTask = new List<Task>();
        con=(Contact)myController.getRecord();
    }

    public Task task1 = new Task();
        public void RDA(){
            Task1.WhoId = con.Id;
            Task1.OwnerId = UserInfo.getUserId();
//            Task1.WhatId = con.AccountId;
            Task1.RDA__c = TRUE;
            listTask.add(Task1);
        }

    public PageReference saveTask(){
        insert listTask;
            {
            PageReference contactPage = new PageReference('/' + con.Id);
            contactPage.setRedirect(true);
            return contactPage;
            }
    }
}

VISUALFORCE PAGE:

<apex:page standardController="Contact" tabStyle="Contact" sidebar="false" extensions="RDATasks" action="{!RDA}">

<apex:form >

<apex:sectionHeader title="Activities"/>
<apex:repeat value="{!listTask}" var="tsk">
    <apex:pageBlock >
        <apex:pageBlockSection >
            <apex:outputField value="{!Contact.Account.Name}" label="Related To"/>
            <apex:outputField value="{!Contact.Name}" label="Name"/>
            <apex:inputField value="{!tsk.Type_of_RDA__c}" style="width:35%"/>
            <apex:inputField value="{!tsk.Subject}" style="width:45%"/>
            <apex:inputField value="{!tsk.ActivityDate}" style="width:35%"/>
            <apex:inputField value="{!tsk.Status}" />
            <apex:inputField value="{!tsk.Description}" style="width:100%"/>
        </apex:pageBlockSection>
    </apex:pageBlock>
</apex:repeat>

    <apex:commandButton value="Add Another RDA" action="{!RDA}"/>
    <apex:commandButton value="Save RDAs" action="{!saveTask}"/>
</apex:form>

</apex:page>

Answer 1

Don't share a reference.

Incorrect

As written, every time you add a "new record", you're just manipulating the same reference to task1.

Task task1 = new Task();
public void RDA()
{
    task1.WhatId = con.Id;
    // other fields;
    listTask.add(task1);
}

Correct

Instantiate a new Task record each time you call the method, and the references will not be shared.

public void RDA()
{
    Task record = new Task();
    record.WhatId = con.Id;
    // other fields
    listTask.add(record);
}

More efficient

You don't even have to cache the record at all, and can specify field=value pairs in the constructor, which is significantly faster.

public void RDA()
{
    listTask.add(new Task(
        WhoId = con.Id,
        // other fields
    ));
}