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Update index.md (#29031)

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Daniel Damilare
2019-03-29 23:10:05 +01:00
committed by Manish Giri
parent 60c796e70d
commit 2353a3c02a
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guide/english/java/arraylist/index.md
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@ -9,20 +9,18 @@ title: ArrayList
```java
import java.util.ArrayList; // is more efficient than importing all of java.util
```
Always import the most specific package in order to save memory size and performance time.
`ArrayList` is a class that is used to create dynamic arrays. It is slower than regular arrays but allows for a lot of manipulation. It should be initialized to have a specific size or it will have the default size of 10 units.
Always import the most specific package in order to save memory size and performance time.
`ArrayList` is a class that is used to create dynamic arrays. It is slower than regular arrays but allows for a lot of manipulation. It should be initialized to have a specific size or it will have the default size of 10 units.
```java
ArrayList<String> names = new ArrayList<>();
ArrayList<Integer> ages = new ArrayList<>(5);
```
In the above snippet, the angle breackets `<>` take a generic data type as argument specifying data type of the elements in the ArrayList. The first ArrayList `names` is specified as containing *String* elements. Thus, it will only be allowed to contain String elements. Its size is not specified so it will have a default size of 10. The second ArrayList `ages` has specified that it will only hold integers. But ArrayList cannot hold primitives, it only holds objects. Thus to make it store integers, floats, etc., we can use wrapper classes. `names` will have a specified size of 5.
In the above snippet, the angle brackets `<>` take a generic data type as argument specifying data type of the elements in the ArrayList. The first ArrayList `names` is specified as containing *String* elements. Thus, it will only be allowed to contain String elements. Its size is not specified so it will have a default size of 10. The second ArrayList `ages` has specified that it will only hold integers. But ArrayList cannot hold primitives, it only holds objects. Thus to make it store integers, floats, etc., we can use wrapper classes. `names` will have a specified size of 5.
Since ArrayList implements *List*, an ArrayList can be created using the following syntax:
```java