Creating an Arraylist of Objects

ArrayList<Matrices> list = new ArrayList<Matrices>();list.add( new Matrices(1,1,10) );list.add( new Matrices(1,2,20) );

How to Creating an Arraylist of Objects.

Create an array to store the objects:

ArrayList<MyObject> list = new ArrayList<MyObject>();

In a single step:

list.add(new MyObject (1, 2, 3)); //Create a new object and adding it to list. 

or

MyObject myObject = new MyObject (1, 2, 3); //Create a new object.list.add(myObject); // Adding it to the list.

If you want to allow a user to add a bunch of new MyObjects to the list, you can do it with a for loop:Let's say I'm creating an ArrayList of Rectangle objects, and each Rectangle has two parameters- length and width.

//here I will create my ArrayList:ArrayList <Rectangle> rectangles= new ArrayList <>(3); int length;int width;for(int index =0; index <3;index++){JOptionPane.showMessageDialog(null, "Rectangle " + (index + 1)); length = JOptionPane.showInputDialog("Enter length"); width = JOptionPane.showInputDialog("Enter width"); //Now I will create my Rectangle and add it to my rectangles ArrayList: rectangles.add(new Rectangle(length,width));//This passes the length and width values to the rectangle constructor,  which will create a new Rectangle and add it to the ArrayList.

}