Java Array to ArrayList to Array

Question

I have an array name "asset" with 4 number. I then converted it to be stored in arraylist. Then with the arraylist copy to another array. Is this algorithm correct? After adding 5 the array should be able to show 5 number now

List assetList = new ArrayList();
String[] asset = {"1", "2", "3", "4"}; 
Collections.addAll(assetList, asset);
assetList.add("5");
String [] aListToArray = new String[assetList.size()];
aListToArray.toArray(aListToArray);

• James: Define correct. What's your actual goal, here? Get a copy of an array? Translate between arrays and ArrayList for an assignment?
• AurA: you can probably do some type safety like List<String> but anyways I am not trying to get why are you coping to a list and copy them back.... had it been a Set I would have understood
• Scary Wombat: it meets my requirements
• BeyondProgrammer: not assignment but I just want to know if this way of doing is right
• Rohit Jain: Why are you using array at all, if the number of elements are varying?

Answer 1

You need to change this line

aListToArray.toArray(aListToArray); // aListToArray to aListToArray itself? This would have given a compilation error

to this

assetList.toArray(aListToArray); // assetList to aListToArray is what you need.

Answer 2

Use just Arrays.asList(asset);

Answer 3

You can make some simplifications:

List assetList = new ArrayList();
String[] asset = {"1", "2", "3", "4"}; 
assetList.addAll(asset);
assetList.add("5");
String [] aListToArray = assetList.toArray(aListToArray);

Overall, the code is correct. However if you want to have a "dynamic array", or a collection of items that changes in size, then don't bother trying to keep something in array form. An arraylist will work fine.

• BeyondProgrammer: how about having first 4 number to be fixed and the rest being dynamically added
• Rogue: If you mean having the first 4 values unchangeable, then why would you have them in a collection if you know what they are? What purpose would that be serving?