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Message: <blockquote data-quote="sihina_lahiru" data-source="post: 7285056" data-attributes="member: 149577">5.Rewriting Interfaces                Consider an interface that you have developed called DoIt: public interface DoIt {    void doSomething(int i, double x);    int doSomethingElse(String s); } Suppose that, at a later time, you want to add a third method to DoIt,   so that the interface now becomes: public interface DoIt {    void doSomething(int i, double x);    int doSomethingElse(String s);    boolean didItWork(int i, double x, String s);    } If you make this change, all classes that implement  the old DoIt interface will break because  they don't implement the interface anymore. Programmers relying  on this interface will protest loudly.   Try to anticipate all uses for your interface and to specify  it completely from the beginning. Given that this is often impossible,  you may need to create more interfaces later. For example, you could  create a DoItPlus interface that extends DoIt: public interface DoItPlus extends DoIt {    boolean didItWork(int i, double x, String s);    }   Now users of your code can choose to continue to use the old interface  or to upgrade to the new interface.         </blockquote>

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