Java Program Example How to Restrict a class to crate only 5 objects in Java.
Question: How to restrict a class from creating multiple objects?
We know by using singleton we can restrict a class to creating multiple objects.But in singleton design pattern can create only one object .So we can use singleton design pattern with some changes please follow the step
Step 1 — Take a class type static variable
private static RestrictObject object;
Step 2 — declare one static int type variable for count (for object creation count)
private static int count;
Step 3 — constructor must be private
private RestrictObject() {
/*every object creation count must be increase by 1*/
System.out.println(“Object created count =” + count);
count++;
}
Step 4 — write one getter method
public static RestrictObject getObject() {
if (count < 6) {
object = new RestrictObject();
}
return object;
}
=================================
package com.blog.example;
public class RestrictObject {
private static RestrictObject object;
private static int count;
private RestrictObject() {
/*every object creation count must be incress by 1*/
count++;
}
public static RestrictObject getObject() {
if (count < 6) {
object = new RestrictObject();
}
return object;
}
}
=======
package com.blog.example;
public class ExampleTesting {
public static void main(String[] args) {
RestrictObject obj1 = RestrictObject.getObject();
RestrictObject obj2 = RestrictObject.getObject();
RestrictObject obj3 = RestrictObject.getObject();
RestrictObject obj4 = RestrictObject.getObject();
RestrictObject obj5 = RestrictObject.getObject();
RestrictObject obj6 = RestrictObject.getObject();
RestrictObject obj7 = RestrictObject.getObject();
RestrictObject obj8 = RestrictObject.getObject();
RestrictObject obj9 = RestrictObject.getObject();
RestrictObject obj10 = RestrictObject.getObject();
System.out.println(obj1.hashCode());
System.out.println(obj2.hashCode());
System.out.println(obj3.hashCode());
System.out.println(obj4.hashCode());
System.out.println(obj5.hashCode());
System.out.println(obj6.hashCode());
System.out.println(obj7.hashCode());
System.out.println(obj8.hashCode());
System.out.println(obj9.hashCode());
System.out.println(obj10.hashCode());
}
}
=====
output
Object created count =0
Object created count =1
Object created count =2
Object created count =3
Object created count =4
Object created count =5
2018699554
1311053135
118352462
1550089733
865113938
1442407170
1442407170
1442407170
1442407170
1442407170
if object has been same , then hash code must be same
