Page Comparison

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Here is the Stub you will use (create it in the test folder - it’s not production code)

package com.s2s.demos.topicmanager;

public class HighestNumberFinder
{
    public int findHighestNumber(int[] array)
    {
        return 89;
    }
}

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1. Create a new interface that is part of the production code, and create it in the com.s2s.demos.findhighestnumber package

2. Code Block
   language c#java
   package com.s2s.demos.findhighestnumber; public interface IHighestNumberFinder { int findHighestNumber(int[] values); }

3. Modify the production version and test version of HighestNumberFinder, so that they both implement the interface IHighestNumberFinder

4. Here is the stub version

5. Code Block
   language java
   package com.s2s.demos.topicmanager; import com.s2s.demos.findhighestnumber.IHighestNumberFinder; // The STUB version public class HighestNumberFinder implements IHighestNumberFinder { @Override public int findHighestNumber(int[] array) { return 89; } }

6. Here is the production version

7. Code Block
   language java
   package com.s2s.demos.findhighestnumber.fin; import com.s2s.demos.findhighestnumber.IHighestNumberFinder; public class HighestNumberFinder implements IHighestNumberFinder { @Override public int findHighestNumber(int[] array) { int highestSoFar = Integer.MIN_VALUE; for( int val : array ) { if( val > highestSoFar ) highestSoFar = val; } return highestSoFar; } }

8. Refactor TopicManager so it now works with the interface IHighestNumberFinder and not directly with the implementation class

9. Code Block
   language java
   package com.s2s.demos.topicmanager; import com.s2s.demos.findhighestnumber.IHighestNumberFinder; import java.util.ArrayList; class TopicManager { private final IHighestNumberFinder highestNumberFinder; public TopicManager() { this.highestNumberFinder = null; } public TopicManager( IHighestNumberFinder hnf ) { highestNumberFinder = hnf; } ...

10. You should find that the test is no longer in an error state

11. Rerun all your tests they should still be passing.

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