35 lines
965 B
Plaintext
35 lines
965 B
Plaintext
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Needing to cast from an <code>interface</code> to a concrete type indicates that something is wrong with the abstractions in use, likely that something is missing from the <code>interface</code>. Instead of casting to a discrete type, the missing functionality should be added to the <code>interface</code>. Otherwise there is the risk of runtime exceptions.
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== Noncompliant Code Example
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----
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public interface MyInterface {
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void doStuff();
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}
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public class MyClass1 implements MyInterface {
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int data;
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public void DoStuff() {
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// TODO...
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}
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}
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public static class DowncastExampleProgram {
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static void EntryPoint(MyInterface interfaceRef) {
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MyClass1 class1 = (MyClass1)interfaceRef; // Noncompliant
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int privateData = class1.data;
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}
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}
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----
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== Exceptions
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Casting to <code>Object</code> doesn't raise an issue, because it can never fail.
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----
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static void EntryPoint(IMyInterface interfaceRef)
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{
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Object o = (Object)interfaceRef;
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...
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}
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----
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