58 lines
1.5 KiB
Java
58 lines
1.5 KiB
Java
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An interface
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public interface AnInterface {
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// can define constants in interfaces
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public static final int MAX_VALUE = 300;
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// but really use interfaces for declaring methods
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public void aMethod();
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public int anotherMethod( String hey ) throws Exception;
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public void yetAnotherMethod() throws Exception, ArithmeticException;
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}
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class ImplementInterfaceClass implements AnInterface {
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public void aMethod() {
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}
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// note that methods are matched on formal parameter types and
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// method name.
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public int anotherMethod( String yep ) throws Exception {
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// note that when you implement an interface, its constants
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// are brought into the defining class's scope
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if( true ) {
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return MAX_VALUE;
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}
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else {
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// however, best to always prefix constants with the defining
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// class or interface for readability purposes
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return AnInterface.MAX_VALUE;
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}
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}
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/**
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* this causes a duplication definition of anotherMethod because
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* the method signature only differs by the return type. In Java,
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* if two method differ only by the return type they are the same method
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* from an inheritance perspective
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*
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public String anotherMethod(String yep) throws Exception
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{
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return null;
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}
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*/
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// finally, you can selectively choose which exception to declare
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// on the throws clause of the implementing method, here we choose to omit
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// Exception
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public void yetAnotherMethod() throws ArithmeticException {
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}
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}
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