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Systems Analysis and Design in a Changing World
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Chapter 4 / Exercise 33
Systems Analysis and Design in a Changing World
Jackson/Satzinger
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We have textbook solutions for you!
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Systems Analysis and Design in a Changing World
The document you are viewing contains questions related to this textbook.
Chapter 4 / Exercise 33
Systems Analysis and Design in a Changing World
Jackson/Satzinger
Expert Verified
153 cl - the class to test Returns:true if the class is a proxy class and false otherwise Throws:NullPointerException- if cl is null getInvocationHandler public static InvocationHandlergetInvocationHandler(Objectproxy) throws IllegalArgumentExceptionReturns the invocation handler for the specified proxy instance. Parameters:proxy - the proxy instance to return the invocation handler for Returns:the invocation handler for the proxy instance Throws:IllegalArgumentException- if the argument is not a proxy instance Explain the final keyword in java. May 22nd, 2008A java variable can be declared using the keyword final. Then the final variable can be assigned only once. A variable that is declared as final and not initialized is called a blank final variable. A blank final variable forces the constructors to initialise it. Java classes declared as final cannot be extended. Restricting inheritance! Methods declared as final cannot be overridden. In methods private is equal to final, but in variables it is not. final parameters – values of the parameters cannot be changed after initialization. Do a small java exercise to find out the implications of final parameters in method overriding. Java local classes can only reference local variables and parameters that are declared as final. A visible advantage of declaring a java variable as static final is, the compiled java class results in faster performance. final (Java)
154 In the Java programming language, the finalkeywordis used in several different contexts to define an entity which cannot later be changed. Contents 1 Final classes2 Final methods3 Final variables4 Difference from the C++ "const" type qualifier5 References6 External linksFinal classes A final classcannot be subclassed. This is done for reasons of security and efficiency. Accordingly, many of the Java standard library classes are final, for example java.lang.Systemand java.lang.String. All methods in a final class are implicitly final. Example: public final class MyFinalClass {...} Final methods A final methodcannot be overriddenby subclasses. This is used to prevent unexpected behavior from a subclass altering a method that may be crucial to the function or consistency of the class.[1]Example: public class MyClass { public final void myFinalMethod() {...} } A common misconception is that declaring a class or method final improves efficiency by allowing the compiler to directly insert the method inline wherever it is called. This is not completely true; the compiler is unable to do this because the classes loaded at runtime might not be the same versions of the ones that were just compiled. Further, the runtime environment and JITcompiler have the information about exactly what classes have been loaded, and are able to make better decisions about when to inline, whether or not the method is final.

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