CODEWITHSUNDEEP
java
Bamo
Bamo

Reputation: 1

how two links are linked together in Java built-in libraries?

for example in Scanner we have obj.next()

but we can call another method after next()

obj.next().charAt(0)

how can I make similar thing for example

obj.getName().toLowerCase()

Upvotes: 0

Views: 48

Answers (1)

Kaan
Kaan

Reputation: 5794

What you have observed – with examples like obj.getName().toLowerCase() – is that when the return type of a method call is itself some other object, then you can immediately call a new method on that newly returned object.

Here's another example: String s = String.class.getName().toLowerCase();. This example could be rewritten like so:

Class<String> stringClass = String.class;
String name = stringClass.getName();
String s = name.toLowerCase();

Both of the one-line and multi-line version of this code result in a String object, referenced by s, which contains the value "java.lang.string".

Note that chaining method calls together is not possible if the return type isn't an object, such as an integer value. For example, here's a method call that results in a primitive long value, which isn't an object, so you can't call any methods on that result – that is, something like millis.hashCode() isn't possible.

long millis = System.currentTimeMillis();

To address your primary question finally: you can create this same behavior by creating methods that return objects instead of primitives (int, long, byte, etc.).

Upvotes: 1

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