#92 ArrayList in Java
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- เผยแพร่เมื่อ 28 พ.ย. 2024
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In this lecture we will learn:
Collection in Java
Use of collection interface and classes
What is the use of Generics?
ArrayList and its properties
How ArrayList is different from Arrays?
Advantages of Collection framework
#1
The collection interface belongs to java.util.Collection package. All classes and methods of collection interface belong to this java.util package.
API means a library or some features that we can use directly, we do not need to define an implementation for it.
Collections List, Queue, Map and Set simply extend the Collection interface and this collection interface must have its own class implementation.
we can also convert a collection into an array.
ArrayList is used like:
Collection nums=new ArrayList();
nums.add(6);
We can add values in a collection by using the add() method.
-- We do not have indexing for the collection API.
In the array, we need to specify its type of it. While Collection API works with objects.
All the data types classes like integer and float extend an object class and thus collection API directly use an object.
#2
To define the data types in collection API, we use Generics.
You can define the type of an object to which data type class it belongs in angular brackets like:
Collection(Integer) nums= new ArrayList Integer ();
Here, we use Integer as it is a class, while int is a primitive data type.
If we do not specify the datatype of a collection object, then it will give a run-time error.
#3
ArrayList is a class that implements a list. The list does not have a method called get because it list works with an index in the values.
It uses a dynamic array to store the duplicate element of different data types.
The ArrayList class maintains the insertion order and is non-synchronized.
The elements stored in the ArrayList class can be randomly accessed.
The size of an ArrayList is increased automatically if the collection grows or shrinks if the objects are removed from the collection.
If you want to use and fetch values from an ArrayList, then you can use Collection.
Collection Integer nums= new ArrayList Integer ();
If you want to work with an index value, you should use List as it supports index values.
List Integer nums= new ArrayList Integer ();
#4 Advantages of Collection Framework:
Consistent API
Reduces programming efforts
Increases program speed and quality
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Your explanations, and the way you teach has improved a lot since those vids I've seen from 6 years ago. Especially the presentation. Great stuff!
hi, I have this error when I write list instead of Collection.
The List type is not generic; cannot be parameterized with arguments
How is it possible?
instead of Collection can we use ArrayList
actually I was watching this video to know about initial capacity and load factor
hi naveen, in which way can i show my 500 row resultset in view page. I am using list i.e i have added all my models in list but, it shows the last record 500 times in view page. And when i try to print list, to check all resultset rows are added , it shows the list something like my model class name 'dk_model'@528fe55
Thanks sir 🙏
Thank you so much please!!!
I have a doubt how did import java.xml.transform.Source ; come like sir I think you didn’t explain about it
Done
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