Objects and Arrays
- If we beed single object to store in program, we have variable.
- And, if we have numbers of objects, we need to create array of objects
- It stores arrays of objects.
- Array of object is not object stored in array, but reference of the object is stored.
How to create array of objects in JAVA?
- Name of the class is followed by square bracket. And then object reference name is given to create array of object
- Example
- Name_Of_Class objectArrayReference[ ]; or
- Name_Of_Class [ ] objectArrayReference ;
- If we hve employee class then we can
- Employee [ ] employeeObjects; or
- Employee employeeObjects[];
How to instantiate the array of objects?
- Syntax is
- Name_of_Class [ ] = new Name_of_Class [length_of_array];
- Example
- Employee [] employeeObject=new Employee [10];
- After array of object is instantiated, you need to create individual elements in array of objects using new keyword.
- Example
- car c[ ] = new car [5]
- c[0] = new car [3762, 13 pa ]
- c [1] = new car [8385, 15 pa ]
Initializing Array of Objects
- after array of object is instantiated; value needs to be iniatialized in it.
- Like in primitive type, we can’t initialize value in array of objects.
- Ways to initialize array of obkects
- By use of constructor
- By use of separate member method
By using Constructer, we initialize array of objects.
Example
Class ICTByte {
Public static void main (String args [])
{
//declaration of array of objects
Employee[] arr;
//allocation of memory for 3 objects to type employee
Arr = new Employee [3];
//initialization of first element
Arr[0]=new Employee (1502, “Ram Bahadur”, “Bhaktapur”);
//initialization of second element
Arr [1] = new Employee (1502, “Shyam”, “Banepa”);
//Displaying result
System.out.println( “Data in arr 0”); arr[0].display();
System.out.println (“Data in 1”); arr[1].display();
}
}
//Creating employee class with id, name and address as attribute
Class Employee{
public int id;
public String name;
public String address;
//Employee class constructor
Employee (int id, String name, String address)
{
this.id = id;
this.name=name;
this.address=address;
//display( ) method to display
Public void display()
{
System.out.println(“Employee id is” + id + “ “+ “name is” + name + “address is” +address);
System.out.println()
}
}
