Course:
Learn Java Programming
In this lesson, you will learn
The switch statement in Java is a multi-branch decision-making control structure. It allows a variable or expression to be tested against multiple constant values and executes the corresponding block of code.
Each value is called a “case”, and the variable being switched on is checked for each case.
Simplifies multiple if–else if conditions
Improves readability and maintainability
Efficient for discrete value comparisons
switch (expression) {
case value1:
// Code block
break; // Optional
case value2:
// Code block
break; // Optional
// You can have any number of case statements.
default: // Optional
// Code block
}
expression: This is the value that is compared with the values of each case. It must be a char, byte, short, int, enum, String, or wrapper class like Character, Byte, Short, or Integer.case value: Each case value must be a unique constant or literal.break: It is used to exit the switch statement. If omitted, the execution will continue into the next case. It prevents fall-through.default: It is executed if none of the cases match the expression. It is optional, but it’s usually a good practice to include it.
package ch5;
public class CheckDays {
public static void main(String[] args) {
int day = 4;
switch (day) {
case 1:
System.out.println("Monday");
break;
case 2:
System.out.println("Tuesday");
break;
case 3:
System.out.println("Wednesday");
break;
case 4:
System.out.println("Thursday");
break;
case 5:
System.out.println("Friday");
break;
case 6:
System.out.println("Saturday");
break;
case 7:
System.out.println("Sunday");
break;
default:
System.out.println("Invalid day");
}
}
}
Thursday
package ch5;
public class CheckMonths {
public static void main(String[] args) {
String month = "July";
switch (month) {
case "January":
System.out.println("Month is January");
break;
case "February":
System.out.println("Month is February");
break;
case "July":
System.out.println("Month is July");
break;
// Additional cases
default:
System.out.println("Unknown month");
}
}
}
Month is July
package ch5;
public class SwitchFallThrough {
public static void main(String[] args) {
int number = 2;
switch (number) {
case 1:
case 2:
case 3:
System.out.println("Number is 1, 2, or 3");
break;
default:
System.out.println("Number is not 1, 2, or 3");
}
}
}
Number is 1, 2, or 3
package ch5;
public class SwitchEnum {
enum Day { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY }
public static void main(String[] args) {
Day day = Day.MONDAY;
switch (day) {
case MONDAY:
System.out.println("Today is Monday");
break;
case FRIDAY:
System.out.println("Today is Friday");
break;
// Other cases
}
}
}
Today is Monday
package ch5;
public class NestedSwitch {
public static void main(String[] args) {
char grade = 'B';
int year = 2;
switch (year) {
case 1:
System.out.println("First Year");
break;
case 2:
switch (grade) {
case 'A':
System.out.println("Excellent");
break;
case 'B':
System.out.println("Very Good");
break;
// Other grades
}
break;
// Other years
}
}
}
Very Good
Both if-else and switch Statements in Java are used for controlling the flow of execution through a program. However, they have different use cases and characteristics.
Here’s a summary table explaining their differences:
| Feature | If-Else | Switch |
|---|---|---|
| Basic Concept | Conditional branches are based on true/false evaluations of expressions. | A branching mechanism based on matching a variable’s value to specific cases. |
| Syntax Complexity | Can get complicated with nested conditions. | Simpler and cleaner, especially with many conditions. |
| Type Support | Can evaluate conditions using any type of expressions that result in a Boolean. | Primarily supports integer, enumerated types, or String objects (in newer versions of Java). |
| Flexibility | More flexible, and can evaluate complex and varied conditions. | Limited to comparing a single variable’s value against multiple cases. |
| Default Behavior | No default statements | Has a default case for handling unmatched cases. |
| Performance | Performance can vary with complexity and the number of conditions. | Generally faster for a large number of cases due to optimization. |
| Use Case | Best for conditions that are not solely based on the value of a single variable or where conditions are complex. | Best for scenarios where a single variable is compared against multiple constant values. |
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