Java Pass-by-Value and Reference

In the provided Java code, the toyNumber variable is passed by value to the play() method. This means that a copy of the variable is created within the method, and any modifications made within the method are not reflected in the original variable. This results in the output showing that the toyNumber in main() remains unchanged after it is modified within the play() method.

To achieve the equivalent of pass-by-reference for primitives in Java, you can consider the following options:

Pass a Reference to an Object
Create a class to encapsulate the primitive variable as a member variable. Pass an instance of this class to the method, effectively passing a reference to the primitive variable.

Return the Modified Value
Modify the play() method to return the modified value of toyNumber. This requires updating the call in main() to assign the returned value to the original variable.

Class or Static Variable
If the two functions are defined within the same class or class instance, you can define toyNumber as a class or static variable. This makes it accessible to both functions and ensures any modifications made are reflected in the original variable.

Single-Element Array
Pass a single-element array containing the primitive variable. This is considered a hack but can be used to achieve pass-by-reference-like behavior.

By adopting these techniques, you can effectively emulate pass-by-reference behavior for primitive types in Java, allowing you to modify the original variables even when they are passed as arguments to methods.