Let's Begin with Collections in java

ArrayList in java

• It is resizable array also called as dynamic array.

• It can remove space from array., when delete operation perform over Arraylist or we can say resize it.

• It contains all ordinary array properties like indexing, maintains order, contiguous memory allocation etc.

• It can be type like Integer, String etc. but, can't be primitive type.

• It is not synchronized in case of threads you have to do it explicitly.

import java.util.ArrayList;
public class Main
{
	public static void main(String[] args) {
		ArrayList<String> list_of_datatypes = new ArrayList<String>();
		
		list_of_datatypes.add("int");
		list_of_datatypes.add("float");
		list_of_datatypes.add("char");
		
		System.out.println(list_of_datatypes);    //array of values stored
		//Output: [int, float, char]
		
		list_of_datatypes.remove("int");    //to remove
		
		System.out.println(list_of_datatypes);
		//Output: [float, char]
		
		System.out.println(list_of_datatypes.get(0)); //at index 0 
		//Output: float
		
		list_of_datatypes.set(1,"int");    //to modify
		
		System.out.println(list_of_datatypes);
		//Output: [float, int]
		
		System.out.println(list_of_datatypes.size());  // to check size
		//Output: 2
	}
}