51 lines
1.1 KiB
Java
51 lines
1.1 KiB
Java
// interfaces/MICollision.java
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// ©2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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import java.util.*;
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interface Bob1 {
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default void bob() { System.out.println("Bob1::bob"); }
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}
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interface Bob2 {
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default void bob() { System.out.println("Bob2::bob"); }
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}
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// class Bob implements Bob1, Bob2 {}
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/* Produces:
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error: class Bob inherits unrelated defaults
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for bob() from types Bob1 and Bob2
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class Bob implements Bob1, Bob2 {}
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^
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1 error
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*/
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interface Sam1 {
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default void sam() { System.out.println("Sam1::sam"); }
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}
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interface Sam2 {
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default void sam(int i) { System.out.println(i * 2); }
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}
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// This works because the argument lists are distinct:
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class Sam implements Sam1, Sam2 {}
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interface Max1 {
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default void max() { System.out.println("Max1::max"); }
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}
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interface Max2 {
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default int max() { return 47; }
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}
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// class Max implements Max1, Max2 {}
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/* Produces:
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error: types Max2 and Max1 are incompatible;
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both define max(), but with unrelated return types
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class Max implements Max1, Max2 {}
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^
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1 error
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*/
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