Must-do problems: Constructors

120 min · Beginner

In every problem the objects are created only through constructors you write: one full constructor that sets the fields, and shorter ones that call it with this(...). Write the class first, check it on the samples, and run every test before opening a hint.

What you will learn

Write a full constructor and shorter ones that fill in defaults with this(...)
Keep rules such as "always in lowest terms" or "always a valid date" inside the constructor
Copy objects and arrays in a constructor so later changes cannot reach them
Build objects that hold references to other objects, and never leave a field null by accident

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