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Java Switch Statement
Introduction:
The switch statement in Java is a control flow statement that allows a variable to be tested for equality against a list of values, known as cases. It's an efficient alternative to using multiple if-else statements.
switch (expression) {
case value1:
// code block
break;
case value2:
// code block
break;
default:
// default code block
}
Example 1: Simple Switch
This example demonstrates a basic switch statement to determine the day of the week based on a number input.
int day = 3;
String dayName;
switch (day) {
case 1:
dayName = "Monday";
break;
case 2:
dayName = "Tuesday";
break;
case 3:
dayName = "Wednesday";
break;
default:
dayName = "Invalid day";
}
System.out.println(dayName);
Console Output:
Wednesday
Switch with Fall-through
Explanation:
In Java, if you don't use a break statement, the switch cases will fall through, executing subsequent cases until a break is encountered.
char grade = 'B';
switch (grade) {
case 'A':
System.out.println("Excellent");
case 'B':
System.out.println("Good");
case 'C':
System.out.println("Fair");
break;
default:
System.out.println("Invalid grade");
}
Console Output:
Good Fair
Switch with Strings
Explanation:
Java switch statements can also handle string values, allowing for more readable code, especially when dealing with specific strings.
String fruit = "Apple";
switch (fruit) {
case "Apple":
System.out.println("Apple is red");
break;
case "Banana":
System.out.println("Banana is yellow");
break;
default:
System.out.println("Unknown fruit");
}
Console Output:
Apple is red
Switch with Enums
Explanation:
Enums are a special Java type used to define collections of constants. Switch statements can be used with enums for better code readability and type safety.
enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY }
Day today = Day.WEDNESDAY;
switch (today) {
case MONDAY:
System.out.println("Start of the work week");
break;
case WEDNESDAY:
System.out.println("Midweek");
break;
case FRIDAY:
System.out.println("End of the work week");
break;
default:
System.out.println("Weekend");
}
Console Output:
Midweek
Nested Switch Statements
Explanation:
Switch statements can be nested within each other to handle more complex conditions. This allows for decision-making based on multiple variables.
int outer = 1;
int inner = 2;
switch (outer) {
case 1:
switch (inner) {
case 1:
System.out.println("Outer 1, Inner 1");
break;
case 2:
System.out.println("Outer 1, Inner 2");
break;
}
break;
default:
System.out.println("Default case");
}
Console Output:
Outer 1, Inner 2
Switch with Multiple Cases
Explanation:
Multiple cases in a switch statement can execute the same block of code by omitting the break statement between them. This is useful for grouping similar cases together.
int month = 4;
String season;
switch (month) {
case 12:
case 1:
case 2:
season = "Winter";
break;
case 3:
case 4:
case 5:
season = "Spring";
break;
default:
season = "Unknown season";
}
System.out.println(season);
Console Output:
Spring
Switch without Break
Explanation:
If a break statement is not used, the switch statement will continue executing the next case even if it doesn't match. This is known as fall-through behavior.
int number = 2;
switch (number) {
case 1:
System.out.println("One");
case 2:
System.out.println("Two");
case 3:
System.out.println("Three");
break;
default:
System.out.println("Unknown number");
}
Console Output:
Two Three
Switch with Default Case
Explanation:
The default case in a switch statement is executed if none of the other cases match the switch expression. It's similar to the else block in if-else statements.
String color = "Purple";
switch (color) {
case "Red":
System.out.println("Color is Red");
break;
case "Blue":
System.out.println("Color is Blue");
break;
default:
System.out.println("Color not recognized");
}
Console Output:
Color not recognized
Switch with Complex Logic
Explanation:
Switch statements can be used to perform more complex logic by combining multiple cases and using additional code within each case.
int score = 85;
switch (score / 10) {
case 10:
case 9:
System.out.println("Grade: A");
break;
case 8:
System.out.println("Grade: B");
break;
case 7:
System.out.println("Grade: C");
break;
default:
System.out.println("Grade: D");
}
Console Output:
Grade: B
Switch with Nested Loops
Explanation:
Switch statements can be combined with loops to perform repetitive tasks based on different conditions.
for (int i = 0; i < 3; i++) {
int number = i;
switch (number) {
case 0:
System.out.println("Zero");
break;
case 1:
System.out.println("One");
break;
default:
System.out.println("Two or more");
}
}
Console Output:
Zero One Two or more
