A method’s declared return type must match the type of value used in the return statement.
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In this articleThe return type of a function establishes the size and type of the value returned by the function and corresponds to the type-specifier in the syntax below: Syntaxfunction-definition: /* attribute-seq is Microsoft-specific */ declaration-specifiers: type-specifier: The type-specifier can specify any fundamental, structure, or union type. If you do not include type-specifier, the return type The return type given in the function definition must match the return type in declarations of the function elsewhere in the program. A
function returns a value when a The following examples illustrate function return values.
This
example defines the Note Efficiency would be enhanced by passing pointers to the structure, rather than the entire structure.
This example defines a function returning a
pointer to an array of characters. The function takes two character arrays (strings) as arguments and returns a pointer to the shorter of the two strings. A pointer to an array points to the first of the array elements and has its type; thus, the return type of the function is a pointer to type You need not declare functions with See alsoC Function Definitions FeedbackSubmit and view feedback for A method's declaration provides a lot of information about the method to the compiler, to the runtime system, and to other classes and objects. Included is not only the name of the method, but also such information as the return type of the method, the number and type of the arguments required by the method, and which other classes and objects can call the method. While this may sound like writing a novel rather than simply declaring a method, most method attributes can be declared implicitly. The only required elements of a method declaration are the method's name, its return type, and a pair of parentheses ( ). This figure shows the elements of a method declaration. Each element of a method declaration is further defined below: accessLevel As with member variables, you control which other classes have access to a method using one of four access levels: public, protected, package, and private. Controlling Access to Members of a Class covers access levels in detail. static As with member variables, static declares this method as a class method rather than an instance method.
Understanding Instance and Class Members talks about declaring instance and class methods. abstract An abstract method has no implementation and must be a member of an abstract class. Refer to Writing Abstract Classes and Methods for information about why you might want to
write an abstract method and how such methods affect subclasses. final A final method cannot be overridden by subclasses. Writing Final Classes and Methods discusses why you might want to write final methods, how they affect subclasses, and whether you might want to write a final class instead. native If you have a significant library of functions
written in another language such as C, you may wish to preserve that investment and use those functions from Java. Methods implemented in a language other than Java are called native methods and are declared as such using the native keyword. Check out our LINKFILE
../../native1.1/index.html ) trail for information about writing native methods. synchronized Concurrently running threads often invoke methods that operate on the same data. These methods may be declared synchronized to ensure that the threads access information in a thread-safe manner. Synchronizing method calls is covered in Doing Two or More Tasks at Once:
Threads. Take particular note of the section entitled Synchronizing
Threads. returnType Java requires that a method declare the data type of the value that it returns. If your method does not return a value, use the keyword void for the return type.
Returning a Value from a Method talks about the issues related to returning values from a method. methodName A method name can be any legal Java identifier. You need to consider several issues in regards to Java method names. These are covered in
Method Names. ( paramlist ) You pass information into a method through its arguments. See the next section, Passing Information into a Method. [throws exceptions] If your method throws any checked exceptions, your method declaration must indicate the type
of those exceptions. See Handling Errors with Exceptionsfor information. In particular, refer to
Specifying the Exceptions Thrown by a Method. Returning a Value from a MethodYou declare a method's return type in its method declaration. Within the body of the method, you use theNow suppose you have a method declared to return a Number : Thepublic Number returnANumber() { . . . } returnANumber method can return an ImaginaryNumber but not an Object . ImaginaryNumber "is a" Number because it's a subclass of Number . However, an Object is not necessarily a Number --it could be a String or some other type. You also can use interface names as return types. In this case, the object returned must implement the specified interface. Java supports method name overloading so that multiple methods
can share the same name. For example, suppose you are writing a class that can render various types of data (strings, integers, and so on) to its drawing area. You need to write a method that knows how to render each data type. In other languages, you have to think of a new name for each method, for example, Overloaded methods are differentiated by the number and type of the arguments passed into the method. In the code sample,class DataRenderer { void draw(String s) { . . . } void draw(int i) { . . . } void draw(float f) { . . . } } draw(String s) and draw(int i) are distinct and unique methods because they require different argument types. You cannot declare more than one method with the same name and the same number and type of arguments because the compiler cannot differentiate
them. So, draw(String s) and draw(String t) are identical and result in a compiler error. A class may override a method in its superclass. The overriding method must have the same name, return type, and parameter list as the method it overrides. Overriding Methods shows you how to override methods. When methods must share data you can pass the data into and return?When methods must share data, you can pass the data into and return the data out of methods. A method could be called using any numeric value as an argument, whether it is a variable, a named constant, or a literal constant. A method's return type is part of its signature.
What are methods with identical names that have identical parameter lists but different return types?If a class has multiple methods having same name but parameters of the method should be different is known as Method Overloading.
What happens when you call a method and the method ends?A variable declared within a method ceases to exist when the method ends. It goes out of scope. A method can also return "nothing" also known as a void method. A method can return a value when it ends.
Is a measure of the strength of the connection between two program methods?In computer programming, cohesion refers to the degree to which the elements inside a module belong together. In one sense, it is a measure of the strength of relationship between the methods and data of a class and some unifying purpose or concept served by that class.
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