Category: Private Methods in Interfaces
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Constants in Interfaces – Object-Oriented Programming
Constants in Interfaces A field declaration in an interface defines a named constant. Naming conventions recommend using uppercase letters, with multiple words in the name being separated by underscores. Such constants are considered to be public, static, and final. These modifiers are usually omitted from the declaration, but can be specified in any order. Such…
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Normal Non-Canonical Record Constructors – Object-Oriented Programming
Normal Non-Canonical Record Constructors A record class declaration can specify any number of non-canonical record constructors—that is, constructors whose signature is not the same as that of the canonical constructor. In Example 5.30, a non-canonical constructor for the record class CD is implemented at (5). It is a zero-argument non-canonical record constructor to create a…
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Sealed Classes and Interfaces 2 – Object-Oriented Programming
A sealed class is declared using the modifier sealed and the optional permits clause in the class header. The permits clause is optional if a sealed class and its permitted direct subclasses are declared in the same compilation unit (p. 317). If a class specifies the permits clause, the class must be declared sealed. The…
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Method Invocation Conversions Involving References – Object-Oriented Programming
5.10 Method Invocation Conversions Involving References The conversions for reference value assignment are also applicable to method invocation conversions, except for the narrowing conversion for constant expressions of non-long integer type (Table 2.17, p. 47). This is reasonable, as parameters in Java are passed by value (§3.10, p. 127), requiring that values of the actual…
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Overloaded Method Resolution – Object-Oriented Programming
Overloaded Method Resolution In this subsection, we take a look at some aspects regarding overloaded method resolution—that is, how the compiler determines which overloaded method will be invoked by a given method call at runtime. Resolution of overloaded methods selects the most specific method for execution. One method is considered more specific than another method…
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Arrays and Subtyping – Object-Oriented Programming
5.7 Arrays and Subtyping Table 5.4 summarizes the types found in Java. Only primitive data and reference values can be stored in variables. Only class and array types can be explicitly instantiated to create objects. Table 5.4 Types and Values Types Values Primitive data types Primitive data values Class, interface, enum, and array types (reference…
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The instanceof Type Comparison Operator 2 – Object-Oriented Programming
As we have seen, the instanceof type comparison operator effectively determines whether the reference value in the reference on the left-hand side refers to an object whose class is a subtype of the type specified on the right-hand side. At runtime, it is the type of the actual object denoted by the reference on the…
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Scope of Pattern Variables – Object-Oriented Programming
Scope of Pattern Variables We first examine the scope of a pattern variable in an if-else statement. If the instanceof pattern match operator returns true in the conditional of an if statement, the pattern variable is introduced and its scope is the if block. Not surprisingly, this is also the case for the if-else statement.…
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Implicit Static Methods for Enum Types – Object-Oriented Programming
Implicit Static Methods for Enum Types All enum types implicitly have the following static methods, and methods with these names cannot be declared in an enum type declaration: Click here to view code image staticEnumTypeName[] values() Returns an array containing the enum constants of this enum type, in the order they are specified. Click here…
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Record Class Basics – Object-Oriented Programming
Record Class Basics A record class in Java is a special-purpose class that simplifies declaration and handling of an aggregate of values that comprise the state of a plain data object. A record class defines immutable fields and the compiler generates the get methods (also called getter or accessor methods) necessary to access the values…