Make immutable Java object

Question

My goal is to make a Java object immutable. I have a class Student. I coded it in the following way to achieve immutability:

public final class Student {  private String name; private String age;  public Student(String name, String age) {     this.name = name;     this.age = age; }  public String getName() {     return name; }  public String getAge() {     return age; }  } 

My question is, what is the best way to achieve immutability for the Student class?

Answer 1

Your class is not immutable strictly speaking, it is only effectively immutable. To make it immutable, you need to use final:

private final String name; private final String age; 

Although the difference might seem subtle, it can make a significant difference in a multi-threaded context. An immutable class is inherently thread-safe, an effectively immutable class is thread safe only if it is safely published.