02 - Linear - Basic - ArrayList

Question 2

What is an ArrayList in Java?

Answer 2

• A resizable array implementation of the List interface
• Can store objects (not primitives directly)
• Allows dynamic resizing, insertion, and removal

```java
ArrayList<String> list = new ArrayList<>();
~~~</String>

Question 3

How do you add elements to an ArrayList?

Answer 3

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
System.out.println(list); // [Apple, Banana]
~~~</String>

Question 4

How do you insert an element at a specific index in an ArrayList?

Answer 4

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
list.add(1, "Orange"); // insert at index 1
System.out.println(list); // [Apple, Orange, Banana]
~~~</String>

Question 5

How do you remove an element by index in an ArrayList?

Answer 5

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
list.remove(0); // remove first element
System.out.println(list); // [Banana]
~~~</String>

Question 6

How do you remove an element by value in an ArrayList?

Answer 6

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
list.remove("Apple"); // remove element with value "Apple"
System.out.println(list); // [Banana]
~~~</String>

Question 7

How do you get an element at a specific index in an ArrayList?

Answer 7

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
String fruit = list.get(0);
System.out.println(fruit); // Apple
~~~</String>

Question 8

How do you find the size of an ArrayList?

Answer 8

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
System.out.println(list.size()); // 2
~~~</String>

Question 9

How do you iterate over an ArrayList in Java?

Answer 9

```java
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");</String>

for (String fruit : list) {
System.out.println(fruit);
}
// Apple
// Banana
~~~