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How to make a Java class immutable ?


Program to demonstrate how to make and code a Java Class Immutable

package com.hubberspot.example;

// 1. Create a class with final keyword
// so that no other class can extend this
// class, to change the state of class
final class Product {

 // 2. Create variables with final keyword
 // so that once values are assigned to it 
 // they cannot be modified
 private final String name;
 private final int count;

 // 3. Create a public constructor which sets
 // the state of these variables
 public Product(String name, int count) {
  this.name = name;
  this.count = count;
 }

 // 4. Generate only the getters method and 
 // no setters, so that no application calling class
 // can change the state of variables
 public String getName() {
  return name;
 }

 public int getCount() {
  return count;
 } 
}

public class ImmutableExample {

 public static void main(String[] args) {

  // 5. Create a Product and assign values in 
  // its constructor
  Product product = new Product("pen" , 1);

  System.out.println(product.getName());
  System.out.println(product.getCount());  

  // 7. No way for the application class
  // to change the state of Product class
  // as there are no setters or a way to 
  // extend the final class , thus immutable
  // class is created
 }
}





Video tutorial to demonstrate how to make a Java class immutable.








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