UML Basics & Access Modifier / PDF

UML Basics & Access Modifier / PDF

The Access Modifiers -- public

npublic access modifier: the + sign in UML

nFields, methods and constructors declared public (least restrictive) within a public class are accessible by all class in the Java program, whether these classes are in the same package or in another package.

nFor simplicity, just take package as the file folder in Windows

nNote: in one application program, there is only and only one public class

nFields/methods are called Class fields/method/member, i.e., you don’t need to create an instance to use them; the convention is to use the classname.methodName notation

The Access Modifiers -- private

nprivate access modifier: the – sign in UML

nThe private (most restrictive) fields or methods cannot be accessed outside the enclosing/declaring class. To make all fields private, provide public getter/setter methods for them.

nThe getter is used to set the values of the data fields

nThe setter is used to change/modifier the fields

The Access Modifiers -- protected

nprotected access modifier: the # sign in UML

nFields, methods and constructors declared protected in a class can be accessed only by subclasses in other packages and by those in the same class even if they are not a subclass of the protected member’s class.

The Access Modifiers -- default

ndefault access modifier: without any sign

nwhen no access modifier is present, any class, field, method or constructor are  accessible only by classes in the same package.

nThis is also called the instance members, i.e., must create an instance of the class before the fields/methods can be used

nUse the instanceName.method() format

UML Basics & Access Modifier / PDF