//Requires
import java.util.ArrayList;
// ArrayList<Data_Type> name = new ArrayList<DataType>(Initial_Capacity);
// for Eg :- If Data Type is int (Use it's wrapper class i.e, Integer)
ArrayList<Integer> anything = new ArrayList<Integer>();
// ArrayList is not initialized with zeroes like an array
import java.util.ArrayList;
ArrayList<Integer> myList = new ArrayList<Integer>();
myList.add(0);
myList.remove(0);//Remove at index 0
myList.size();
myList.get(0);//Return element at index 0
// Create
String[] myArray = {"A", "B", "C"};
// constructor no.3, passing a collection
List<String> myArrayList = new ArrayList<>(Arrays.asList("A", "B", "C"));
// Get element
String i = myArray[1];
String j = myArrayList.get(1);
// Get size
int k = myArray.length; // length is a public field in array, not method.
int l = myArrayList.size();
// Add an element, you can't that w/ array as it is fixed in length
myArrayList.add("D");
// Set an element
myArray[0] = "E";
myArrayList.set(0, "E");
// Remove an element, can't w/ array b/c fixed length
myArrayList.remove(2); // remove by index
myArrayList.remove("E"); // remove by object
//ArrayList
ArrayList is a part of collection framework and is present in java.util package. It provides us dynamic arrays in Java. Though, it may be slower than standard arrays but can be helpful in programs where lots of manipulation in the array is needed.
ArrayList inherits AbstractList class and implements List interface.
ArrayList is initialized by a size, however the size can increase if collection grows or shrunk if objects are removed from the collection.
Java ArrayList allows us to randomly access the list.
ArrayList can not be used for primitive types, like int, char, etc. We need a wrapper class for such cases.
Code to create a generic integer ArrayList :
ArrayList<Integer> arrli = new ArrayList<Integer>();