Make immutable Java object

java immutability
Ruchira Gayan Ranaweera picture Ruchira Gayan Ranaweera · Aug 12, 2013 · Viewed 64.2k times · Source

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

assylias picture assylias · Aug 12, 2013

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.

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