ArrayList in Java

Question 1

what is an ArrayLists?

Answer 1

An ArrayLists is a resizable Array.

Question 2

How do you create an ArrayLists?

Answer 2

1. ArryList<Integer> integers;
   // null
   integers = new ArrayList<>();
   // the the object in the
   memory
   2.</Integer>

Question 3

How do you add element to an array list?

Answer 3

1. you can add element to an array list by using the Add(); method.
   a. fruits.add(“apple”);
   fruits.add(“Bananna);
   b.add(index , element)
   fruits.add(0 , apple);

Question 4

How do you access element in an ArrayLists?

Answer 4

1. you can access an element using the get(); method
   a.fruit.get(0);
   // get the first element in the ArrayList

Question 5

How do you change element in an ArrayList?

Answer 5

1. we can change the element in the arrayList by using the set method.
   a. set(index, element)
   fruit.set(0, orange);
   // change the first element
   to orange in the array list.

Question 6

How do you remove an element in an ArrayList?

Answer 6

To remove an element use the remove(); method
a.to remove by index:
fruit.remove(0);
// remove the first element in
the arraylist.

b. to remove by value:
fruit. remove(“apple”);
// remove the value apple from the arrayList

c. to remove all element use the clear(); method
fruit.clear();

Question 6

How do we get the Size of an ArrayList?

Answer 6

To get the size of An ArrayList use the size(); method

a. fruit.size();
// get the size of the arraylist.

Question 6

How to loop through an array list?

Answer 6

You can use a for loop to loop through an arraylist.
example:
for(int i = 0; i < fruit.size(); i++)
System.out.print(fruit.get(i));
// this loop and get the element in the array list using the size(); method

Question 7

How do you sort An ArrayList?

Answer 7

To sort An array list you use the sort(); method from the collection class then pass the name of the arraylist to the sort(); method

Question 7

what is the for each loop?

Answer 7

the for each loop is use for iterating over array and arraylists.

Question 8

how to declare a for each loop

Answer 8

for( Type - varname : Arraylists/array)
example: itemArraylist.add(“orange);
for(String item : itemArrayList)
system.out.print(item + “ “

Question 10

Why do we use array?