[Edit] Java: Switch

content/java/concepts/switch/switch.md

@@ -3,22 +3,24 @@ Title: 'Switch'
 Description: 'A switch statement provides a means of checking an expression against various case statements.'
 Subjects:
   - 'Computer Science'
+  - 'Web Development'
 Tags:
-  - 'Switch'
   - 'Conditionals'
   - 'Control Flow'
+  - 'Switch'
+  - 'Values'
 CatalogContent:
   - 'learn-java'
   - 'paths/computer-science'
 ---
 
-A **`switch`** statement provides a means of checking an expression against various `case` statements. If there is a match, the code within starts to execute. The `break` keyword can be used to terminate a case.
+A **`switch`** statement provides a means of checking an expression against various `case` statements. If there is a match, the code within starts to execute. The `break` keyword can be used to terminate a case. There's also an optional `default` statement marking code that executes if none of the `case` statements are true.
 
-There's also an optional `default` statement marking code that executes if none of the `case` statements are true.
+The `switch` statement is especially useful when dealing with discrete values, such as enums, characters, and integers. It improves readability and simplifies decision-making in code compared to long chains of `if-else` conditions.
 
 ## Syntax
 
-A `switch` statement looks like:
+A `switch` statement (or a `switch` case) looks like:
 
 ```pseudo
 switch (expression) {
@@ -33,33 +35,133 @@ switch (expression) {
 }
 ```
 
-- The `switch` keyword initiates the statement and is followed by `()`, which contains the value that each case will compare. In the example, the value or expression of the switch statement is `grade`.
-- Inside the block, `{}`, there are multiple cases.
-- The `case` keyword checks if the expression matches the specified value that comes after it. The value following the first case is `9`. If the value of grade is equal to `9`, then the code that follows the `:` would run.
-- The `break` keyword tells the computer to exit the block and not execute any more code or check any other cases inside the code block.
-- At the end of each switch statement, there is a `default` statement. If none of the cases are `true`, then the code in the `default` statement will run. It’s essentially the `else` part in an `if`/`else if`/`else` statement.
+Here, `expression` is the expression to be checked against the various `case` statements.
+
+## How Switch Case Works
+
+1. Java evaluates the `expression` inside the `switch` case.
+2. It compares the result with each `case` value.
+3. If a match is found, the code block under that `case` is executed.
+4. The `break` statement ends the `switch` block.
+5. If no match is found, the `default` block (if present) is executed.
+
+> **Note:** Without `break`, the execution will continue to the next case—this is called fall-through.
+
+## Switch vs. If-Else
 
-In the code above, suppose grade is equal to `10`, then the output would be “Sophomore”.
+| Feature                  | `switch` Case                             | `if-else` Statement                       |
+| ------------------------ | ----------------------------------------- | ----------------------------------------- |
+| **Use Case**             | Best for fixed values or discrete options | Suitable for complex conditions or ranges |
+| **Data Types Supported** | `int`, `char`, `String`, `enum`           | All data types and expressions            |
+| **Readability**          | More readable for many discrete cases     | Less readable with many nested conditions |
+| **Fall-through**         | Possible if `break` is omitted            | No fall-through                           |
+| **Performance**          | Slightly better for large case sets       | Comparable in most cases                  |
 
-> **Note:** Without the `break` keyword at the end of each case, the program would execute the code for the first matching case and _all_ subsequent cases, including the `default` code. This behavior is different from `if`/`else` conditional statements which execute only one block of code.
+## Example 1: Basic Integer Switch
 
-## Example
+This example uses an `int` variable to determine the current day of the week using a `switch` statement. It prints the corresponding weekday based on the numeric value:
 
 ```java
-int rating = 3;
+public class DaySwitch {
+  public static void main(String[] args) {
+    int day = 3;
 
-switch (rating) {
-  case 5:
-    System.out.println("Exceptional");
-    break;
-  case 4:
-    System.out.println("Good");
-    break;
-  case 3:
-    System.out.println("Fair");
-    break;
-  default:
-    System.out.println("Poor");
-    break;
+    switch (day) {
+      case 1:
+        System.out.println("Monday");
+        break;
+      case 2:
+        System.out.println("Tuesday");
+        break;
+      case 3:
+        System.out.println("Wednesday");
+        break;
+      default:
+        System.out.println("Other day");
+    }
+  }
+}
+```
+
+Here is the output:
+
+```shell
+Wednesday
+```
+
+## Example 2: Switch with String
+
+This example shows how to use a string in a `switch` statement to match and identify the month. It's available from Java 7 onwards:
+
+```java
+public class MonthSwitch {
+  public static void main(String[] args) {
+    String month = "April";
+
+    switch (month) {
+      case "January":
+        System.out.println("1st month");
+        break;
+      case "April":
+        System.out.println("4th month");
+        break;
+      default:
+        System.out.println("Unknown month");
+    }
+  }
+}
+```
+
+Here is the output:
+
+```shell
+4th month
+```
+
+## Example 3: Enhanced Switch (Java 14+)
+
+This example demonstrates the enhanced `switch` syntax introduced in Java 14. It uses the new arrow (`->`) syntax for cleaner and safer case handling, and returns a value based on day type:
+
+```java
+public class EnhancedSwitch {
+  public static void main(String[] args) {
+    int day = 5;
+
+    String dayType = switch (day) {
+      case 1, 2, 3, 4, 5 -> "Weekday";
+      case 6, 7 -> "Weekend";
+      default -> "Invalid day";
+    };
+
+    System.out.println(dayType);
+  }
 }
 ```
+
+Here is the output:
+
+```shell
+Weekday
+```
+
+## Frequently Asked Questions
+
+### 1. Can `switch` statements be used with strings in Java?
+
+Yes, from Java 7 onwards, `switch` statements support `String` as a valid type.
+
+### 2. What happens if `break` is not used?
+
+Without break, the execution falls through to the next case, which may lead to unexpected behavior.
+
+### 3. Can a `switch` expression return a value?
+
+Yes, starting with Java 14, the enhanced `switch` allows returning a value directly using the `->` syntax.
+
+### 4. Can we use boolean in `switch` statements?
+
+No, boolean is not supported in Java `switch` statements. Use `if-else` instead.
+
+### 5. Is the `default` case mandatory?
+
+No, but it's a good practice to include it to handle unexpected values.