How to set submitted values of <h:inputText> inside <ui:repeat> into map, set or list

Does that help The String class is immutable and doesn't have a setter for the value. The getter is basically the Object#toString() method.
You need to get/set the value directly on the List instead. You can do that by the list index which is available by .

code :

---

<ui:repeat value="#{mrBean.stringList}" varStatus="loop">
    <h:inputText value="#{mrBean.stringList[loop.index]}" />
</ui:repeat>

Any of those help Your problem is not connected with PrimeFaces 's behaviour, but rather with a scoping problem that is implicilty created when using the tag.
First of all, let's depart from your example. Basically, you've got

code :

---

<ui:repeat value="#{bean.strings}" var="s">
    <h:inputText value="#{s}"/>
</ui:repeat>

public class MString {
    private String string;//getter+setter+constructor
}

<ui:repeat value="#{bean.mstrings}" var="ms">
    <h:inputText value="#{ms.string}"/>
</ui:repeat>

<ui:repeat value="#{bean.strings}" var="s" varStatus="status">
    <h:inputText value="#{bean.strings[status.index]}"/>
</ui:repeat>

around this issue It's caused because you're (re)creating the list in the getter method behind . This method is invoked during every iteration round. So, every next iteration will basically trash the values set during the previous iteration. In the action method, you end up with the list as created during the last iteration round. That's why the last entry seems to work fine.
This approach is indeed absolutely not right. You should not be performing business logic in getter methods at all. Make the list a property and fill it only once during bean's (post)construction.

code :

---

@ManagedBean(name = "genproducts")
@ViewScoped
public class Genproducts{

    private List<Product> list;

    @PostConstruct
    public void init() throws SQLException {
        list = new ArrayList<>();
        // ...
    }

    public List<Product> getList() {
        return list;
    }

} 

<ui:repeat value="#{genproducts.list}" var="itemsBuying">

wish help you to fix your issue As BalusC reported here String is immutable.
Use the varStatus attribute to access directly the list member by the index.

this will help You need to associate the input value with the repeated variable var in some way. Right now you're not doing that anywhere and basically binding all input values to one and same bean property. So, when the form gets submitted, every iteration will override the bean property everytime with the value of the current iteration round until you end up getting the value of the last iteration round. This is definitely not right.
The simplest way would be to directly associate it with the object represented by var: