CODEWITHSUNDEEP
javaprimitive-types
deltanovember
deltanovember

Reputation: 44051

Is it possible to define custom types in java that work with primitives?

For example the following is syntactically correct code

Double number = 10.0;

Is it possible to define my own class such as Price

Price myPrice = 10.0;

Actually compiles ?

Upvotes: 7

Views: 15564

Answers (4)

Saurabh Gokhale
Saurabh Gokhale

Reputation: 46395

No, you can't define your own primitive types for numerical quantities.

Declaring Price myPrice means that the variable myPrice will be of type Price and will be used to as its instance.

You can have following valid.

Suppose you declare variable myPrice of type Price. Some instance variables can be accessed via that myPrice reference.

Price myPrice = new Price();
myPrice.value = 10.0;
myPrice.currency = "Dollar"; 
etc ....

Upvotes: 2

Mykhailo Gaidai
Mykhailo Gaidai

Reputation: 3160

You can't extend Double class, since it is final.

But you can extend Number class and implement Comparable interface - the way actual Double class is created.

Upvotes: 1

Bohemian
Bohemian

Reputation: 425003

No. It's hard-wired into the language.

Only primitives may be instantiated without the new keyword, except String, which although not a primitive, may be assigned using primitive syntax. ie both new String("foo") and "foo" will do it (note though that these are not exactly the same).

Upvotes: 0

Nick
Nick

Reputation: 5805

Auto-boxing and auto-unboxing only works with primitives. The concept you are talking about is similar to C++ conversions. Unfortunately, there is no such thing in Java. The best you can do is

Price myPrice = new Price(10.0);

Upvotes: 7

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