Separate values from List

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I’m using List to sort some values, but I need to separate them after I manipulated the values.

List<Map.Entry<String,Integer>> lista = new ArrayList<Map.Entry<String,Integer>>(fila);

And to print I’m using:System.out.println(lista);

And so it returns to me all the elements of the list. [c=30, e=25, b=20].

My intention would be to pass this to an array, for example, because my list is small (as in case 3). 'Cause if you go to a vector, I can only access the position I want.

java list array
  • 1

    You can only access the position you want using Arraylist as well, try this: lista.get(0);, it will return you only the first element of the list. This is no longer enough for you?

  • I completely forgot about . get(). I will use it to use the pass to vector, I need to work with vector in this part. Thank you @Math

  • 1

    To transform from Arraylist to Vector you can do so: Integer vetor[] = lista.toArray(new Integer[lista.size()]);

  • 1

    @Math I will use this way that you yourself said... thanks again! As always you saving me... I owe you beers, in case you drink :D

3 answers

4


One java.util.List can be accessed directly by the index, as below:

List<Integer> list = ...
Integer first = list.get(0);
Integer last = list.get(list.size() - 1);

But if you still wish to turn her into one array, utilize:

Object[] array = list.toArray();

or

Integer[] array = list.toArray(new Integer[0]);

Reference and more infortmasons: http://docs.oracle.com/javase/6/docs/api/java/util/List.html

  • Better than that, that’s all.

  • 1

    Your last line of code returned me the following error: Type mismatch: cannot convert from Object[] to Integer[]. There’s something wrong there, no?

  • It’s true! list.toArray() always returns a Object[], to return a defined type, the other method must be used toArray(...), as follows: list.toArray(new Integer[0]). Detailed documentation

  • 1

    Now it worked :) how about [Dit] your answer and fix such information?

1

To return a given value from a list position you can run the following code:

System.out.println(list.get(Indice));

I think you don’t need to pass your list to an array because an array only "works" with a type of data, but in the case you have a MAP works with the concept of key-value, ie, list has a key and value associated.

0

Do not use vector, use maps (Map) or implement hashCode and and equals of the object and work as follows.

List<Integer> lista = new ArrayList<Integer>();
lista.add(new Integer(30));
lista.add(new Integer(25));
lista.add(new Integer(20));
Integer oject = new Integer(25);

int index = lista.indexOf(oject);
if (index > -1)
{
   System.out.println(lista.get(index));
}

In my case my object is Integer as you have, but can make an object as needed and will be the same formula. lista.indexOf(oject), so you take any position dynamically.

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