CODEWITHSUNDEEP
javaarraylist
Brian
Brian

Reputation: 525

Adding to an ArrayList Java

I am a beginner to java, and need some help.

I am trying to convert an Abstract Data type Foo which is an associated list to an Arraylist of the strings B. How do you loop through the list and add each string to the array.

I may be over thinking it, but I am lost now.

Thanks for the help in advance.

Upvotes: 44

Views: 261229

Answers (7)

Aravind A
Aravind A

Reputation: 21

Array list can be implemented by the following code: 

Arraylist<String> list = new ArrayList<String>();
list.add(value1);
list.add(value2);
list.add(value3);
list.add(value4);

Upvotes: 2

Rahul Raj
Rahul Raj

Reputation: 3459

If you're using Java 9, there's an easy way with less number of lines without needing to initialize or add method.

List<String> list = List.of("first", "second", "third");

Upvotes: 0

Adam200214
Adam200214

Reputation: 17

thanks for the help, I've solved my problem :) Here is the code if anyone else needs it :D

import java.util.*;

public class HelloWorld {


public static void main(String[] Args) {

Map<Integer,List<Integer>> map = new HashMap<Integer,List<Integer>>();
List<Integer> list = new ArrayList<Integer>();
list.add(1);
list.add(9);
list.add(11);
map.put(1,list);        

    int First = list.get(1);
    int Second = list.get(2);

    if (First < Second) {

        System.out.println("One or more of your items have been restocked. The current stock is: " + First);

        Random rn = new Random();
int answer = rn.nextInt(99) + 1;

System.out.println("You are buying " + answer + " New stock");

First = First + answer;
list.set(1, First);
System.out.println("There are now " + First + " in stock");
}     
}  
}

Upvotes: 0

Mohammad Najar
Mohammad Najar

Reputation: 2009

If you have an arraylist of String called 'foo', you can easily append (add) it to another ArrayList, 'list', using the following method:

ArrayList<String> list = new ArrayList<String>();
list.addAll(foo);

that way you don't even need to loop through anything.

Upvotes: 13

madth3
madth3

Reputation: 7344

Well, you have to iterate through your abstract type Foo and that depends on the methods available on that object. You don't have to loop through the ArrayList because this object grows automatically in Java. (Don't confuse it with an array in other programming languages)

Recommended reading. Lists in the Java Tutorial

Upvotes: 1

pcalcao
pcalcao

Reputation: 15988

Instantiate a new ArrayList:

List<String> myList = new ArrayList<String>();

Iterate over your data structure (with a for loop, for instance, more details on your code would help.) and for each element (yourElement):

myList.add(yourElement);

Upvotes: 51

Terhands
Terhands

Reputation: 179

You should be able to do something like:

ArrayList<String> list = new ArrayList<String>();
for( String s : foo )
{
    list.add(s);
}

Upvotes: 4

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