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# Introduction | ||
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There are various idiomatic approaches to solve Bob. | ||
A basic approach can use a series of `if` statements to test the conditions. | ||
An array can contain answers from which the right response is selected by an index calculated from scores given to the conditions. | ||
In this exercise, we’re working on a program to determine Bob’s responses based on the tone and style of given messages. Bob responds differently depending on whether a message is a question, a shout, both, or silence. Various approaches can be used to implement this logic efficiently and cleanly, ensuring the code remains readable and easy to maintain. | ||
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## General guidance | ||
## General Guidance | ||
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Regardless of the approach used, some things you could look out for include | ||
When implementing your solution, consider the following tips to keep your code optimized and idiomatic: | ||
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- If the input is trimmed, [`trim()`][trim] only once. | ||
- **Trim the Input Once**: Use [`trim()`][trim] only once at the start to remove any unnecessary whitespace. | ||
- **Use Built-in Methods**: For checking if a message is a question, prefer [`endsWith("?")`][endswith] instead of manually checking the last character. | ||
- **DRY Code**: Avoid duplicating code by combining the logic for determining a shout and a question when handling shouted questions. Following the [DRY][dry] principle helps maintain clear and maintainable code. | ||
- **Single Determinations**: Use variables for `questioning` and `shouting` rather than calling these checks multiple times to improve efficiency. | ||
- **Return Statements**: An early return in an `if` statement eliminates the need for additional `else` blocks, making the code more readable. | ||
- **Curly Braces**: While optional for single-line statements, some teams may require them for readability and consistency. | ||
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- Use the [`endsWith()`][endswith] `String` method instead of checking the last character by index for `?`. | ||
## Approach: Method-Based | ||
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- Don't copy/paste the logic for determining a shout and for determining a question into determining a shouted question. | ||
Combine the two determinations instead of copying them. | ||
Not duplicating the code will keep the code [DRY][dry]. | ||
```java | ||
class Bob { | ||
String hey(String input) { | ||
var inputTrimmed = input.trim(); | ||
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if (isSilent(inputTrimmed)) | ||
return "Fine. Be that way!"; | ||
if (isYelling(inputTrimmed) && isAsking(inputTrimmed)) | ||
return "Calm down, I know what I'm doing!"; | ||
if (isYelling(inputTrimmed)) | ||
return "Whoa, chill out!"; | ||
if (isAsking(inputTrimmed)) | ||
return "Sure."; | ||
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return "Whatever."; | ||
} | ||
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private boolean isYelling(String input) { | ||
return input.chars() | ||
.anyMatch(Character::isLetter) && | ||
input.chars() | ||
.filter(Character::isLetter) | ||
.allMatch(Character::isUpperCase); | ||
} | ||
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- Perhaps consider making `questioning` and `shouting` values set once instead of functions that are possibly called twice. | ||
private boolean isAsking(String input) { | ||
return input.endsWith("?"); | ||
} | ||
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- If an `if` statement can return, then an `else if` or `else` is not needed. | ||
Execution will either return or will continue to the next statement anyway. | ||
private boolean isSilent(String input) { | ||
return input.length() == 0; | ||
} | ||
} | ||
``` | ||
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- If the body of an `if` statement is only one line, curly braces aren't needed. | ||
Some teams may still require them in their style guidelines, though. | ||
This approach defines helper methods for each type of message—silent, yelling, and asking—to keep each condition clean and easily testable. For more details, refer to the [Method-Based Approach][approach-method-based]. | ||
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## Approach: `if` statements | ||
## Approach: `if` Statements | ||
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```java | ||
import java.util.function.Predicate; | ||
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} | ||
``` | ||
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For more information, check the [`if` statements approach][approach-if]. | ||
This approach utilizes nested `if` statements and a predicate for determining if a message is a shout. For more details, refer to the [`if` Statements Approach][approach-if]. | ||
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## Approach: answer array | ||
## Approach: Answer Array | ||
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```java | ||
import java.util.function.Predicate; | ||
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} | ||
``` | ||
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For more information, check the [Answer array approach][approach-answer-array]. | ||
This approach uses an array of answers and calculates the appropriate index based on flags for shouting and questioning. For more details, refer to the [Answer Array Approach][approach-answer-array]. | ||
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## Which Approach to Use? | ||
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Choosing between the method-based approach, `if` statements, and answer array approach can come down to readability and maintainability. Each has its advantages: | ||
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## Which approach to use? | ||
- **Method-Based**: Clear and modular, great for readability. | ||
- **`if` Statements**: Compact and straightforward, suited for smaller projects. | ||
- **Answer Array**: Minimizes condition checks by using indices, efficient for a variety of responses. | ||
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Since benchmarking with the [Java Microbenchmark Harness][jmh] is currently outside the scope of this document, | ||
the choice between `if` statements and answers array can be made by perceived readability. | ||
Experiment with these approaches to find the balance between readability and performance that best suits your needs. | ||
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[trim]: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#trim() | ||
[endswith]: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#endsWith(java.lang.String) | ||
[dry]: https://en.wikipedia.org/wiki/Don%27t_repeat_yourself | ||
[approach-method-based]: https://exercism.org/tracks/java/exercises/bob/approaches/method-based | ||
[approach-if]: https://exercism.org/tracks/java/exercises/bob/approaches/if-statements | ||
[approach-answer-array]: https://exercism.org/tracks/java/exercises/bob/approaches/answer-array | ||
[jmh]: https://github.com/openjdk/jmh | ||
Check failure on line 135 in exercises/practice/bob/.approaches/introduction.md GitHub Actions / Lint Markdown filesLink and image reference definitions should be needed
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exercises/practice/bob/.approaches/method-based/content.md
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# Method-Based Approach | ||
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In this approach, the different conditions for Bob’s responses are separated into dedicated private methods within the `Bob` class. This method-based approach improves readability and modularity by organizing each condition check into its own method, making the main response method easier to understand and maintain. | ||
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The main `hey` method determines Bob’s response by delegating each condition to a helper method (`isSilent`, `isYelling`, and `isAsking`), each encapsulating specific logic. | ||
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## Explanation | ||
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This approach simplifies the main method `hey` by breaking down each response condition into helper methods: | ||
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1. **Trimming the Input**: | ||
Check failure on line 11 in exercises/practice/bob/.approaches/method-based/content.md GitHub Actions / Lint Markdown filesTrailing spaces
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The `input` is trimmed using the `String` [`trim()`][trim] method to remove any leading or trailing whitespace. This helps to accurately detect if the input is empty and should prompt a `"Fine. Be that way!"` response. | ||
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2. **Delegating to Helper Methods**: | ||
Each condition is evaluated using the following helper methods: | ||
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- **`isSilent`**: Checks if the trimmed input has no characters. | ||
- **`isYelling`**: Checks if the input is all uppercase and contains at least one alphabetic character, indicating shouting. | ||
- **`isAsking`**: Verifies if the trimmed input ends with a question mark. | ||
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This modular approach keeps each condition encapsulated, enhancing code clarity. | ||
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3. **Order of Checks**: | ||
The order of checks within `hey` is important: | ||
- Silence is evaluated first, as it requires an immediate response. | ||
- Shouted questions take precedence over individual checks for yelling and asking. | ||
- Yelling comes next, requiring its response if not combined with a question. | ||
- Asking (a non-shouted question) is checked afterward. | ||
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This ordering ensures that Bob’s response matches the expected behavior without redundancy. | ||
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## Code structure | ||
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```java | ||
class Bob { | ||
String hey(String input) { | ||
var inputTrimmed = input.trim(); | ||
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if (isSilent(inputTrimmed)) | ||
return "Fine. Be that way!"; | ||
if (isYelling(inputTrimmed) && isAsking(inputTrimmed)) | ||
return "Calm down, I know what I'm doing!"; | ||
if (isYelling(inputTrimmed)) | ||
return "Whoa, chill out!"; | ||
if (isAsking(inputTrimmed)) | ||
return "Sure."; | ||
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return "Whatever."; | ||
} | ||
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private boolean isYelling(String input) { | ||
return input.chars() | ||
.anyMatch(Character::isLetter) && | ||
input.chars() | ||
.filter(Character::isLetter) | ||
.allMatch(Character::isUpperCase); | ||
} | ||
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private boolean isAsking(String input) { | ||
return input.endsWith("?"); | ||
} | ||
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private boolean isSilent(String input) { | ||
return input.length() == 0; | ||
} | ||
} | ||
``` | ||
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## Advantages of the Method-Based Approach | ||
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- **Readability**: Each method is clearly responsible for a specific condition, making the main response logic easy to follow. | ||
- **Maintainability**: Changes to a condition can be confined to its method, minimizing impacts on the rest of the code. | ||
- **Code Reusability**: Helper methods can be reused or adapted easily if new conditions are added in the future. | ||
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## Considerations | ||
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- **Efficiency**: While this approach introduces multiple method calls, it enhances readability significantly, which is often more valuable in non-performance-critical applications. | ||
- **Error Prevention**: This approach avoids redundant code, reducing the risk of maintenance errors. | ||
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## Shortening Condition Checks | ||
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If each `if` statement body is only a single line, braces can be omitted, or the test expression and result could be placed on a single line. However, [Java Coding Conventions][coding-conventions] recommend always using curly braces for error prevention and easier future modifications. | ||
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### Alternative: Inline Helper Methods | ||
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For smaller projects, consider implementing helper methods inline or as lambdas, though this might reduce readability. | ||
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[trim]: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#trim() | ||
[coding-conventions]: https://www.oracle.com/java/technologies/javase/codeconventions-statements.html#449 |