Class Definition » New

Creating Objects

Using the new keyword. new is always followed by the constructor of the class.

For example, to create an Employee object, you write:

Employee employee = new Employee();

Here, 'employee' is an object reference of type Employee.

Once you have an object, you can call its methods and access its fields, by using the object reference. You use a period (.) to call a method or a field.

For example:

objectReference.methodName objectReference.fieldName

The following code, for instance, creates an Employee object and assigns values to its age and salary fields:

public class MainClass {   public static void main(String[] args) {     Employee employee = new Employee();     employee.age = 24;     employee.salary = 50000;   } } class Employee {     public int age;     public double salary;     public Employee() {     }     public Employee(int ageValue, double salaryValue) {         age = ageValue;         salary = salaryValue;     } }

When an object is created, the JVM also performs initialization that assign default values to fields.

 Memory Leak Demo

class List {
  MemoryLeak mem;
  List next;
}

class MemoryLeak {
  static List top;

  char[] memory = new char[100000];

  public static void main(String[] args) {
    for (int i = 0; i < 100000; i++) {
      List temp = new List();
      temp.mem = new MemoryLeak();
      temp.next = top;
      top = temp;
    }
  }
}

 

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