JAVA

JAVA

1. MODIFIERS

   • public - Visible to all
   • private - visible only to class
   • protected - visible only to the package or inheritance
   • default - visible only to the package
   • final - in the class it isn't allowed to extend , in method it isn't allowed to @Overwrite and in the variable it isn't allowed to change the value
   • ABSTRACT
     • ABSTRACT CLASS: Can't be instantiated;
     • ABSTRACT METHOD: All classes that inherit an abstract class must have the abstract methods of the inherited class; An abstract method requires a class in which he is to be abstract;
     • METHOD IN AN ABSTRACT CLASS: Methods can be implemented;
     • ARRAYS OF ABSTRACT CLASS: From an array with an abstract class type, you can have an array with all the subclasses that the abstract class inherits.
   • static - the variable will have the same value in all instances and in the method, can be accessed directly (no instance)

2. Constructors

3. Inheritance

4. Polymorphism

5. Encapsulation

6. Interfaces

7. Exceptions

8. Packages

   • lang
   • Math
   • IO

9. Threads

10. ERROS

    • COMPILE ERROR: The program is out of the grammatical rules of the language.
    • EXECUTION ERROR: The program is in accordance with the grammatical rules, but has a logical error.