Returning this for a fluent API
this is a reference to the object the current method or constructor is running on. You use it to tell a field from a parameter with the same name, to pass or return the current object, and (as this(...)) to call another constructor.
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Practice questions
Write the code in the editor, run it, then open the model answer to compare.
Write a class Person with fields name and age, a constructor that uses parameters with the same names, and a method isOlderThan(Person other) that uses this.age and other.age. Show it with two people.
Write a fluent class Text with methods add(String s), space() and upper() that each return this, and a toString() returning the built text. Build HELLO WORLD with one chain.
Write a class Node with int value and Node next, and a method Node link(Node n) that sets this.next = n and returns n. Build the list 1 -> 2 -> 3 in one chain and print it.
Explain it without notes
What does this refer to inside an instance method, and inside a constructor?
Why does name = name; in a constructor compile but not work?
Give two reasons to pass or return this, with an example of each.
Why can't static methods use this?
Expected output
tea samosa samosa = 45
same object? true
tea samosa samosa water = 55