How to access specific element of array stored in arraylist?

Question

I have following code

List<double[]> alParent = new ArrayList<>();
alParent.add(new double[]{15.22,25.22});
alParent.add(new double[]{1.1,2.3});
double tempone[] = {1,2};
double temptwo[] = {4,5};
alParent.add(tempone);
alParent.add(temptwo);

I have stored array of type double[] inside arraylist. I want to access elements from arraylist which are on first position and second position double[] array. For my example I want to access 15.22,1.1,1,4 and 25.22,2.3,2,5 separately. Is there any way i can get specific elements stored inside arraylist? Also, if i have more elements in arraylist how do i get my desire result?

Firstly, I would start using generics: List<double[]> alParent = new ArrayList<>();. Next, have a look at the ArrayList documentation - see which of those methods sounds like it will get a specific element... — Jon Skeet
– Jon Skeet, Commented Sep 15, 2016 at 5:42
List.get(index) returns item at a specific index and then select desired double value from array. for example alParent.get(0)[0] will return fist arrays 0th element i.e. 15.22 — Sanjeev
– Sanjeev, Commented Sep 15, 2016 at 5:45
@JonSkeet I am not looking for direct method. Is there any other way i can do this? — Raj Tandel
– Raj Tandel, Commented Sep 15, 2016 at 5:47
What do you mean by "I am not looking for direct method"? It's not clear what you're expecting here, but alParent.get(row)[column] is about as simple as it gets... if you want all the elements in a given column, just iterate over the rows... — Jon Skeet
– Jon Skeet, Commented Sep 15, 2016 at 5:48

soufrk · Accepted Answer · 2016-09-15 07:09:48Z

1

use blow code:

double temp1[] = new double[alParent.size()];    
double temp2[] = new double[alParent.size()];    
for (int i = 0; i < alParent.size(); i++) {    
    temp1[i] = alParent.get(i)[0];    
    temp2[i] = alParent.get(i)[1];    
}

temp1 and temp2 are arrays you want.

edited Sep 15, 2016 at 7:09

soufrk

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answered Sep 15, 2016 at 5:56

Jack

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Comments

Sanzio Angeli · Accepted Answer · 2022-05-31 02:37:05Z

0

Suppose we have an array, arr = [2, 4, 5, 6], and we want to store all elements into an empty ArrayList.

int arr[] = {2,4,5,6}; 
ArrayList<Integer> al =  new ArrayList<Integer>();
for (int i = 0; i < arr.length; i++){
    int num = arr[i];
    al.add(i, num);
}

// print the value of ArrayList 
for (int i = 0; i < arr.length; i++){
    System.out.println(al.get(i));
}

edited May 31, 2022 at 2:37

Sanzio Angeli

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answered May 29, 2022 at 14:23

Faizan Alam

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