I need a array object, that should holds 3 Objects.
At first was using Collection
, but I need to add to a specific place. for example:
CollectionObject.add(pos, myObject)
Then I went to ArrayList
, created object like this:
ArrayList<MyObject> array = new ArrayList<MyObject>();
When creating this, it creats array with size 1, but I need to add to position 0-2, so adding like:
array.add(2, myObject)
I got :
java.lang.IndexOutOfBoundsException: Index: 2, Size: 1
My solution is, create arraylist, add 3 empty objects to it, and later overwrite, but any more subtle solution? Are there any better array holding objects, like Vector
or something?
Use an array of 3 elements instead as follows:
MyObject [] array = new MyObject[3];
array[2] = myObject;
ArrayList
is not an array, it is a List
implemented using a hidden array. You need to add three items to it before you can address items by index, like this:
ArrayList<MyObject> array = new ArrayList<MyObject>(3);
array.add(null);
array.add(null);
array.add(null);
array.set(2, myObject)
ArrayList
s grow automatically. If you do not need this functionality, you use a plain array, for example, like this:
MyObject array = new MyObject[] {myObject1, myObject2, myObject3};
Now you can replace items by using the indexing operator:
array[2] = newMyObject;
MyObject[] a = new MyObject[3];
a[2] = new MyObject();
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