You can do it like this:
list.add(1, object1)
list.add(2, object3)
list.add(2, object2)
After you add object2 to position 2, it will move object3 to position 3.
If you want object3 to be at position3 all the time I'd suggest you use a HashMap with position as key and object as a value.
Answer from superM on Stack OverflowYou can do it like this:
list.add(1, object1)
list.add(2, object3)
list.add(2, object2)
After you add object2 to position 2, it will move object3 to position 3.
If you want object3 to be at position3 all the time I'd suggest you use a HashMap with position as key and object as a value.
You can use Array of objects and convert it to ArrayList-
Object[] array= new Object[10];
array[0]="1";
array[3]= "3";
array[2]="2";
array[7]="7";
List<Object> list= Arrays.asList(array);
ArrayList will be- [1, null, 2, 3, null, null, null, 7, null, null]
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To insert value into ArrayList at particular index, use:
public void add(int index, E element)
This method will shift the subsequent elements of the list. but you can not guarantee the List will remain sorted as the new Object you insert may sit on the wrong position according to the sorting order.
To replace the element at the specified position, use:
public E set(int index, E element)
This method replaces the element at the specified position in the list with the specified element, and returns the element previously at the specified position.
Here is the simple arraylist example for insertion at specific index
ArrayList<Integer> str=new ArrayList<Integer>();
str.add(0);
str.add(1);
str.add(2);
str.add(3);
//Result = [0, 1, 2, 3]
str.add(1, 11);
str.add(2, 12);
//Result = [0, 11, 12, 1, 2, 3]