Switch Statement

Switch statement accepts expression (like variable or constant) and executes one of many code blocks.

Syntax

switch (expression) { case val1: // code to execute if expression is equal to val1 break; case val2: // code to execute if expression is equal to val2 break; case val3: // code to execute if expression is equal to val3 break; default: // code to execute if expression is NOT equal to // val1, val2 nor val3 break; }

case specifies the value to check.

break separates code blocks.

defaultis used to handle cases when expression's value doesn't match any of the cases. It's not mandatory to specify

Basic Example

Let's look at a program that converts number into traffic light color.

Rules are the following:

• 1 - red
• 2 - yellow
• 3 - green

public class Main { public static void main(String[] args) { int number = 2; String color = ""; switch (number) { case 1: color = "red"; break; case 2: color = "yellow"; break; case 3: color = "green"; break; } System.out.println(color); } }

Output:

yellow

Since the value of number is 2, the code at lines 11 executes.

Default Example

Let's analyze a program that depending on angles count prints shape name.

Rules are the following:

• 3 - Triangle
• 4 - Quadrilateral
• 5 - Pentagon
• Any other value is considered invalid

public class Main { public static void main(String[] args) { int anglesCount = 2; String shape; switch (anglesCount) { case 3: shape = "Triangle"; break; case 4: shape = "Quadrilateral"; break; case 5: shape = "Pentagon"; break; default: shape = "Invalid"; break; } System.out.println(shape); } }

Output:

Invalid

Since anglesCount is neither of the cases value (3, 4, 5) the code at line 17 executes.

Multiple Values Case

A code block inside case can be executed for one or more values.

Let's have a program that rates performance depending on it's score.

Rules are the following:

• 0 to 3 - low
• 4 to 7 - medium
• 8 to 10 - high

public class Main { public static void main(String[] args) { int performance = 8; String rate = ""; switch (performance) { case 0: case 1: case 2: case 3: rate = "low"; break; case 4: case 5: case 6: case 7: rate = "average"; break; case 8: case 9: case 10: rate = "high"; break; } System.out.println(rate); } }

Output:

high

performance value is matched by case 8 and thus line 22 executes.