![]() ![]() One defines for an object certain âmethodsâ, which, given an object and optionally some further input, a programmer may call on that object, to obtain certain output.This input is typically âstoredâ inside the object. one might construct an object of type âmathematicianâ with input: ânameâ, âuniversityâ, âresearch fieldâ. One constructs an object by providing certain input.Note: true, false, and null are not keywords, but they are literals and reserved words that cannot be used as identifiers.Object oriented programming languages are, roughly speaking, ones in which the programmer works primarily with âobjectsâ which have the following characteristic aspects: Indicates that an attribute is not cached thread-locally, and is always read from the "main memory" Specifies that a method should not have a return value Indicates what exceptions may be thrown by a methodĪ non-accesss modifier, which specifies that an attribute is not part of an object's persistent state Refers to the current object in a method or constructor Selects one of many code blocks to be executedĪ non-access modifier, which specifies that methods can only be accessed by one thread at a time Restrict the precision and rounding of floating point calculations Static methods/attributes can be accessed without creating an object of a class ![]() New in Java 9įinished the execution of a method, and can be used to return a value from a methodĪ data type that can store whole numbers from -32768 to 32767Ī non-access modifier used for methods and attributes. Specifies required libraries inside a module. Specifies that a method is not implemented in the same Java source file (but in another language)Īn access modifier used for attributes, methods and constructors, making them only accessible within the declared classĪn access modifier used for attributes, methods and constructors, making them accessible in the same package and subclassesĪn access modifier used for classes, attributes, methods and constructors, making them accessible by any other class Used to declare a special type of class that only contains abstract methodsĪ data type that can store whole numbers from -9223372036854775808 to 9223372036854775808 Used to import a package, class or interfaceĬhecks whether an object is an instance of a specific class or an interfaceĪ data type that can store whole numbers from -2147483648 to 2147483647 ![]() Used with exceptions, a block of code that will be executed no matter if there is an exception or notĪ data type that can store whole numbers from 3.4e−038 to 3.4e+038 New in Java 9Įxtends a class (indicates that a class is inherited from another class)Ī non-access modifier used for classes, attributes and methods, which makes them non-changeable (impossible to inherit or override) Used together with while to create a do-while loopĪ data type that can store whole numbers from 1.7e−308 to 1.7e+308ĭeclares an enumerated (unchangeable) typeĮxports a package with a module. Specifies the default block of code in a switch statement Marks a block of code in switch statementsĬatches exceptions generated by try statementsĪ data type that is used to store a single characterĬontinues to the next iteration of a loopĭefines a constant. The body is provided by the subclass (inherited from)Ī data type that can only store true and false valuesĪ data type that can store whole numbers from -128 and 127 An abstract method can only be used in an abstract class, and it does not have a body. Used for classes and methods: An abstract class cannot be used to create objects (to access it, it must be inherited from another class). Variables, methods, classes, or any other identifiers: KeywordĪ non-access modifier. Java has a set of keywords that are reserved words that cannot be used as
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