A summary of common mistakes when learning Java Bronze.
-Fields are constants only </ b> All fields are implicitly qualified with final static </ b>. (Modifiers can be omitted) Fields can be qualified with static (* Because the value defined by static can be executed without creating an instance)
-All methods are implicitly qualified with public abstract </ b> </ b> You cannot qualify a method with static. (* Static methods cannot be modified because they can be executed without creating an instance.)
You cannot access the instance field defined in your class from the static method. </ b> → A compilation error has occurred!
Static methods can be executed without creating an instance. A compile error occurs to prevent the instance field from being accessed from the static method before creating the instance.
Assigning an instance of a parent class to a child class type. Forcible type conversion is possible by using the cast operator.
No compilation error occurs. However!
The moment you actually try to assign, an exception occurs (ClassCastException) </ b>
Assigning an instance of a child class to the type of a parent class.
Executing a method that is in the parent class but not in the child class will result in a compilation error </ b>.
-Method name -Number of arguments -Argument type -Argument order
That
Variables are initialized with a default value when they are created.
・ Byte type 0 ・ Short type 0 ・ Int type 0 ・ Long type 0L ・ Float type 0.0f ・ Double type 0.0d ・ Char type'\ u0000' ・ Boolean type false -Reference type null
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