In this article, we will learn and demonstrate simple example based on Switch case statement with different data type like int, char and then finally String
1. Till Java 6:
- Switch case statement can iterate over either int or char data type
- No feature to iterate over String data type
- This is the shortcoming and Java developers are forced to use if-else-if conditional statement impacting performance at times
2. Post Java 7 release,
- With the release of Java version 7, a new feature to iterate over String data type has been added
- Much to the relief of Java developer who are forced to use alternate if-else-if conditional statement
- Switch case statement with String data type has a good performance over multiple if-else-if chained condition
- String data type compares the string passed with equals() method from String class
- As you can see, it uses equals() method from String class which clearly indicates that the comparison is CASE-Sensitive
- Handle null case properly otherwise will end up with NullPointerException
Let us see an example for each one,
- Switch Case With int data type
- Switch Case With char data type
- Switch Case With String data type
- Switch Case with String data type for null input
2.1 Switch Case with int data-type
SwitchCaseWithInt.java
package in.bench.resources.programs;
public class SwitchCaseWithInt {
public static void main(String[] args) {
String day = checkDayOfWeekBasedOnNumber(5);
System.out.println(day);
}
private static String checkDayOfWeekBasedOnNumber(int inputDayNumber){
String dayOfWeek = null;
switch (inputDayNumber) {
case 1:
dayOfWeek = "Monday";
break;
case 2:
dayOfWeek = "Tuesday";
break;
case 3:
dayOfWeek = "Wednesday";
break;
case 4:
dayOfWeek = "Thursday";
break;
case 5:
dayOfWeek = "Friday";
break;
case 6:
dayOfWeek = "Saturday";
break;
case 7:
dayOfWeek = "Sunday";
break;
default:
dayOfWeek = inputDayNumber + " is invalid input day no.";
}
return dayOfWeek;
}
}
Output:
Friday
2.2 Switch Case with char data-type
SwitchCaseWithChar.java
package in.bench.resources.programs;
public class SwitchCaseWithChar {
public static void main(String[] args) {
String fruit = checkFruitBasedOnChar('d');
System.out.println(fruit);
}
private static String checkFruitBasedOnChar(char inputFruitChar) {
String fruitName = null;
switch (inputFruitChar) {
case 'a':
fruitName = "A for Apple";
break;
case 'b':
fruitName = "B for Banana";
break;
case 'c':
fruitName = "C for Cherry";
break;
case 'd':
fruitName = "D for Date Plum";
break;
default:
fruitName = inputFruitChar + " is invalid input fruit char";
}
return fruitName;
}
}
Output:
D for Date Plum
2.3 Switch Case with String data-type
SwitchCaseWithString.java
package in.bench.resources.programs;
public class SwitchCaseWithString {
public static void main(String[] args) {
String returnQuarterResult = checkQuarterBasedOnMonth("April");
System.out.println(returnQuarterResult);
}
private static String checkQuarterBasedOnMonth(String inputMonthStr){
String quarter = null;
switch (inputMonthStr) {
case "January":
quarter = "It is start of LAST quarter acc. to some region";
break;
case "April":
quarter = "It is start of FIRST quarter acc. to some region";
break;
case "July":
quarter = "It is start of SECOND quarter acc. to some region";
break;
case "October":
quarter = "It is start of THIRD quarter acc. to some region";
break;
default:
quarter = "It's NOT start of any quarter acc. to some region";
}
return quarter;
}
}
Output:
It is start of FIRST quarter according to some region
2.4 Switch Case with String data-type for null input
SwitchCaseWithString.java
package in.bench.resources.programs;
public class SwitchCaseWithString {
public static void main(String[] args) {
String returnQuarterResult = checkQuarterBasedOnMonth(null);
System.out.println(returnQuarterResult);
}
private static String checkQuarterBasedOnMonth(String inputMonthStr){
String quarter = null;
switch (inputMonthStr) {
case "January":
quarter = "It is start of LAST quarter acc. to some region";
break;
case "April":
quarter = "It is start of FIRST quarter acc. to some region";
break;
case "July":
quarter = "It is start of SECOND quarter acc. to some region";
break;
case "October":
quarter = "It is start of THIRD quarter acc. to some region";
break;
default:
quarter = "It's NOT start of any quarter acc. to some region";
}
return quarter;
}
}
Output:
Exception in thread "main" java.lang.NullPointerException
at in.bench.resources.programs.SwitchCaseWithString
.checkQuarterBasedOnMonth(SwitchCaseWithString.java:14)
at in.bench.resources.programs.SwitchCaseWithString
.main(SwitchCaseWithString.java:6)
Solution:
- Perform null check with if condition to avoid NullPointerException
That’s all folks !!
Related Articles:
- Java Constructor with example
- Default constructor
- Parametrized constructor
- Default constructor v/s Parametrized constructor
- Constructor overloading
- Constructor chaining
- Constructor v/s Methods
- Private Constructor
- Static constructor in Java – A big interview question ?
- Constructor in Java Interface
References:
- https://docs.oracle.com/javase/8/docs/technotes/guides/language/strings-switch.html
- https://docs.oracle.com/javase/tutorial/java/nutsandbolts/switch.html
Happy Coding !!
Happy Learning !!
