A switch statement allows programmers to control the flow of execution in their code by testing for a specific value and executing a corresponding block of code.
In this programming tutorial, we will take a deep dive into understanding how switch statements work in Java and why they are useful. We will explore the syntax, usage, and common gotchas when working with switch statements.
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What is a Switch Statement in Java?
The switch statement is a powerful feature of the Java programming language and removes the need to write multiple if-else statements when we have to process multiple conditions. The switch statement has one mandatory argument: the expression based on which the switch will be made, (i.e., based on which the code block pertaining to the matching case statement will be executed). It should be noted that the switch statement is compliant with int, long, byte, short, String, and enum types. You can have one or more case statements and, optionally, one default statement in a switch statement.
Additionally, since Java 7, programmers can also use Strings in their switch statements. In each case, the value specified must match the value of the expression for the associated block of code to be executed.
If there is no match between the values given inside cases and the value of the expression given inside the switch, then none of the code blocks will get executed. If none of your case blocks match, but you want something to happen anyway, then there is something called default that you can use for that purpose.
Despite the benefits, there are certain downsides to using switch statements in Java. Switch statements are hard to debug and they do not work well with objects or Strings that have multiple possible values. Moreover, they can lead to code that is hard to maintain if the condition in the switch expression changes often.
How Switch Statements in Java Work?
The switch statement is a control flow statement used in Java, which means that it determines the flow of program execution. It can be used to select one of several possible execution paths and is typically used to replace multiple if-else-if statements or a series of nested if statements.
The switch statement evaluates an integer expression or String literal, then compares it with each case label until a match is found. If none of the case labels match, no further processing occurs and the switch statement terminates without executing any statements between its matching label and end.
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Syntax of the Switch Statement in Java
The syntax of the switch statement in Java is as follows:
switch(expression)
{
case label1:
//Write your code here
break;
case label2:
//Write your code here
break;
default:
//Write your code here
}
The expression can be a variable, constant, or expression that evaluates to an integer value.
How to Program the Switch Statement in Java
The switch statement is most often used when you have a number of different options that you want to evaluate. For example, consider the following code snippet:
int number = 1;
switch (number)
{
case 1: System.out.println("You selected option 1.");
break;
case 2: System.out.println("You selected option 2.");
break;
case 3: System.out.println("You selected option 3.");
break;
default: System.out.println("You've selected an invalid option.");
}
In the preceding code example, the switch statement has been used to evaluate the value of the variable number. If number is equal to 1, the text message “You selected option 1.” is displayed. If number is equal to 2, the text message “You selected option 2.” is displayed, and so on.
Note how the default statement has been used. If the value of the variable number is not 1 or 2 or 3, the text message “You’ve selected an invalid option.” will be displayed.
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Java Switch Statement Considerations
Here are some important things to remember and best practices to follow when working with switch statements in Java:
- A switch expression may have one or N possible case statements.
- The type of the value in a case statement must be identical to the type used in the switch expression.
- The value of a case statement must be constant.
- The values of two case statements cannot be the same. The compiler will flag an error if a duplicate value is detected.
- The supported data types for the Java switch expression are int, long, byte, short, String, and enum types.
- A break statement is optional after each case statement. The break statement will terminate the switch statement and skip the control to the code block immediately following the switch…..case construct.
- Multiple case statements can have the same code block.
- A switch statement evaluates case patterns vertically, from top to bottom.
- When the first case pattern matches the expression, the statement in the first case pattern is evaluated.
- The switch statement has one mandatory argument: the expression upon which the switch will be made.
Final Thoughts on Java Switch Statements
The Java Programming Language enables developers to take advantage of switch statements to manage the execution flow of your code. In a switch statement, you have the option of including one or more case statements, as well as a default statement (optional). It should be noted that case patterns are evaluated from top to bottom. In this Java programming tutorial, we looked at how the switch statement works and some of the ways it can be used in Java applications.
