CODEWITHSUNDEEP
javaarrayslistmerge
psychic_retard
psychic_retard

Reputation: 33

How to [flat] merge Merge Multiple Arrays into List in Java

How can I [flat] merge multiple arrays into a single List<String>?

For example:

private String title[] = { "Cup Cake", "Donut", "Eclair", "Froyo",
        "Ginger Bread", "Honey Comb", "Icecream Sandwich", "Jelly Bean" };

private String desc[] = { "version: 1.5", "version: 1.6",
        "version: 2.0 & 2.1", "version: 2.2", "version: 2.3",
        "version: 3.0", "version: 4.0", "version: 4.1" };

private int thumb[] = {3,4,7,8,10,11,15,16};

Upvotes: 0

Views: 9281

Answers (5)

dmitryvinn
dmitryvinn

Reputation: 412

Source:

private String title[] = { "Cup Cake", "Donut", "Eclair", "Froyo",
    "Ginger Bread", "Honey Comb", "Icecream Sandwich", "Jelly Bean" };

private String desc[] = { "version: 1.5", "version: 1.6",
    "version: 2.0 & 2.1", "version: 2.2", "version: 2.3",
    "version: 3.0", "version: 4.0", "version: 4.1" };`

private int thumb[] = {3,4,7,8,10,11,15,16};

Assuming you want to have a list of Strings:

final List<String> original = Stream.of(title, desc).collect(Collectors.toList());
original.addAll(Stream.of(thumb).map(String::valueOf).collect(Collectors.toList()));

Upvotes: 1

Tacocat
Tacocat

Reputation: 1134

Assuming that you wish to add the array of Integers into the same List of Strings:

import java.util.Arrays;     
import java.util.List;  
import java.util.ArrayList;  

public class StringArrayTest  
{
    public static void main(String[] args)  
    {
        String title[] = { "Cup Cake", "Donut", "Eclair", "Froyo",
        "Ginger Bread", "Honey Comb", "Icecream Sandwich", "Jelly Bean" };

        String desc[] = { "version: 1.5", "version: 1.6",
        "version: 2.0 & 2.1", "version: 2.2", "version: 2.3",
        "version: 3.0", "version: 4.0", "version: 4.1" };

        int thumb[] = {3,4,7,8,10,11,15,16};

        List<String> nameList = new ArrayList(Arrays.asList(title));
        nameList.addAll(Arrays.asList(desc));
        nameList.add(Arrays.toString(thumb)); //adds thumb as a single string entry
   }  
}

Upvotes: 2

user4910279
user4910279

Reputation:

Try this

List<Object> list =
    Stream.of(Stream.of(title), Stream.of(desc), IntStream.of(thumb).mapToObj(i -> i))
    .flatMap(s -> s)
    .collect(Collectors.toList());
System.out.println(list);

Upvotes: 6

Mart&#237;n Mu&#241;oz del R&#237;o
Mart&#237;n Mu&#241;oz del R&#237;o

Reputation: 1968

All your elements need to be of the same type, for example String.

You can try something like:

import java.util.Arrays;  
import java.util.List;  
import java.util.ArrayList;  

public class StringArrayTest  
{
    public static void main(String[] args)  
    {
        String title[] = { "Cup Cake", "Donut", "Eclair", "Froyo",
        "Ginger Bread", "Honey Comb", "Icecream Sandwich", "Jelly Bean" };

        String desc[] = { "version: 1.5", "version: 1.6",
        "version: 2.0 & 2.1", "version: 2.2", "version: 2.3",
        "version: 3.0", "version: 4.0", "version: 4.1" };

        List<String> newList = new ArrayList<String>();
        newList.addAll( Arrays.asList(title));
        newList.addAll(Arrays.asList(desc));

        for (String e : newList)  
        {  
            System.out.println(e);  
        } 
   }  
}

Upvotes: 0

Devman
Devman

Reputation: 310

You will need to iterate over each of them. Also, each element in the list will need to be the same type (unless you want them all to be Object. try:

list List<String> = new ArrayList<String>
// First array
for (String s: title) {
    list.add(s);
}
// Do the same for other arrays

Alternatively

list List<Object> = new ArrayList<Object>
// First array
for (Object s: title) {
    list.add(s);
}

In the second case, the list is just less useful since you would have to end up manually type checking everthing before calling any methods on the elements.

Upvotes: 0

Related Questions