Java list Store list elements in entity class and display them in jsf page datatable

Question

I have list of string such this:

List<String> lista = Arrays.asList("Water","Pomegranate","Fish","Potato","Milk","Grape","steaks","parsley");//The list is big of that

This list repeat the category each 4 time I want to fetch each element under its category column as this in jsf page:

Drinks      Fruits           Meat      Vegetables

Water.       Pomegranate.    Fish.     Potato
Milk.        Grape.          steaks.   parsley

              ِِِِ... the others ...

I create Entity class:

public class Entity
{
      private String drink;
      private String fruit;
      private String meat;
      private String vegetable;
      // getter and setter
}

How to do that?

I want to display element 0,4,8,12 .. in first column and element 1,5,9,13 in the second column and element 2,6,10,14 in the third column and element 3,7,11,15 in the fourth column and so on

Each element must be under its category

           <p:layout fullPage="true"> 
                 <h:form> 
                        <p:dataTable var="data" value="#{bean.list}">
                            <p:column headerText="Drinks" >
                                #{data.drink}
                            </p:column>
                        <p:column headerText="Fruits" >
                                #{data.fruit}
                            </p:column>

                        <p:column headerText="Meats" >
                                #{data.meat}
                            </p:column>

                        <p:column headerText="Vegis" >
                                #{data.vegetable}
                            </p:column>

                        </p:dataTable>

                    </h:form>

            </p:layout>

You need to know how you classify each item. If you know how to classify the items, you can store them in a Map> where the key is the category and the list is the corresponding items. — Assafs, Aug 03 '17 at 08:06
I want to display element 0,4,8,12 .. in first column and element 1,5,9,13 in the second column and element 2,6,10,14 in the third column and element 3,7,11,15 in the fourth column and so on — Wasfy, Aug 03 '17 at 08:07
Possible duplicate of [How to print out all the elements of a List in Java?](https://stackoverflow.com/questions/10168066/how-to-print-out-all-the-elements-of-a-list-in-java) — Kindle Q, Aug 03 '17 at 08:27
jsf page ? there no detail of jsf page in your question. Show what you have done and ask what exactly you want. — Harish Barma, Aug 03 '17 at 08:32

score 0 · Accepted Answer · answered Aug 03 '17 at 08:08

The list doesn´t know anything about a category. You need to define a specific index for each category by your own.

final int CATEGORY_DRINK = 0;
final int CATEGORY_FRUIT = 1;
final int CATEGORY_MEAT = 2;
final int CATEGORY_VEGETABLE = 3;
final int CATEGORY_COUNT = 4;

int repeat = list.size() / CATEGORY_COUNT; //2
for(int i = 0; i < repeat; i++) {
    int offset = i * CATEGORY_COUNT;
    String drink = list.get(CATEGORY_DRINK + offset);
    String fruit = list.get(CATEGORY_FRUIT + offset);
    String meat = list.get(CATEGORY_MEAT + offset);
    String vegi = list.get(CATEGORY_VEGETABLE + offset);
}

Alternatively, you can try to use an other data structure. A map could be used to map a category to a list of values.

thanks for your answer It will help me more to retrieve them to jsf/primefaces datatable. — Wasfy, Aug 03 '17 at 09:10

T. Jung · Answer 2 · 2017-08-03T09:17:30.630

0

You can do it like this:

for(int i=0; i<lista.size();i=+4){
   for(int j=0; j<4; j++){
     if(j==0){
        string obj = lista.get(i+j);
        //add the string to the first list
     }
     if(j==1){
        string obj = lista.get(i+j);
        //add the string to the second list
     }
     if(j==2){
        string obj = lista.get(i+j);
        //add the string to the third list
     }
     if(j==3){
        string obj = lista.get(i+j);
        //add the string to the forth list
     }
   }
}

edited Aug 03 '17 at 09:17

answered Aug 03 '17 at 08:08

T. Jung

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in your answer lista.length() must be lista.size() and itry your code but it is not executed thanls on anyway. – Wasfy Aug 03 '17 at 09:12

Java list Store list elements in entity class and display them in jsf page datatable

2 Answers2