switch case in java

Java Switch Case

A conditional statement in Java that tests many values and produces one result is known as a switch statement. Cases are the various values that are checked. It resembles a statement with multiple branches. Since Java 7 was released, the user can also use strings in a lot of situations. The syntax to use a Java switch case is described as follows:

switch(exp)

{

case value:

     //FirstStatement

     break;

case value x :

    //SecondStatement

    break;

default:

    //ThirdStatement

}

When the user declares a Java switch case, there are a few guidelines to follow. The following considerations should be made when developing a Java switch case.

• In a switch instance, we cannot specify duplicate values.
• In a switch case, the case values and the variable's data type must match.
• In this situation, only literals or constants are permitted. Variables are not permitted.
• The break statement accomplishes the goal of stopping the execution of the sequence.
• The break statement is not required; if it is not present, the execution will proceed on to the following statement.
• Additionally optional, the default statement may occur anywhere within the block.

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Uses of Java Switch Statement 

One of several code blocks can be chosen for execution in Java using the switch case.

Break keyword: The control exits the switch block as soon as Java hits a break keyword. When this keyword is encountered, code execution halts, and case testing within the block is completed as soon as a match is discovered. Because it disregards the remainder of the execution of the code whenever there is a break, considerable time of execution is saved.

Default Keyword: It is used for describing the code that is run when no test case matches the expression.

How does Java Switch work

This is how Java's switch case function works

Java's switch case allows many conditions to be checked simultaneously, similar to an if-else ladder. An input that may be a fixed or a direct expression that may be examined is given to Switch. Each test case's value is compared against the expression's value until a match is made. The corresponding code is executed if the default keyword when specified, does not find a match. Otherwise, the code designated for the test case that matches it is run.

When using the Java switch case, keep the following in mind:

• The values of the 2 cases cannot be the same.
• The switch's variable must have the same data type as the values in all of the test cases.
• For the circumstances, the value must be literal or constant; it cannot be a variable. For instance:

Switch (1+2+3+4) and Switch (1*2+3%4) are valid expressions.

Switch(ef+gh), and Switch(e+f+g) are invalid expressions.

• The switch's statement chain can be ended with the break statement.
• The test case values do not have to match (ascending or descending). It can take place as needed.
• The execution will move on to the following test case if the break statement is not included.
• The default statement may appear anywhere in the Java switch block, if it does not appear at the end, a break statement must come after it.
• Nesting is permitted, although it complicates the software.

Rules to remember while using Switch Statement

• The only types of variables that may be used in a switch statement are enums, byte, short, and convertible integers (short, byte, or char).
• A switch may contain any no of case statements. The value that has to be compared to followed by a colon follow each case.
• Case values must be constants or literals, and they should be of the same type of data as the variable in the switch.
• The statements after a case will run unless a break statement is found when the variable that is being switched on equals that case.
• The switch statement ends whenever a break statement is encountered, and the control moves to the line after the switch statement.
• It's not necessary to have a break in every circumstance. In the absence of a break, the control will pass to consecutive cases until one is reached.
• An additional default case that must come at the end of a switch statement is permitted. Whenever none of the situations apply, a task can be completed using the default case. In the default instance, there is no break required.

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Examples of Switch case in java

Let us see a Java example to understand the switch case in a better manner:

public class Main {

  public static void main(String[] args) {

int mon = 6;

    switch (mon) 

    {

      case 1:

        System.out.println("Jan");

        break;

      case 2:

        System.out.println("Feb");

        break;

      case 3:

        System.out.println("Mar");

        break;

      case 4:

        System.out.println("Apr");

        break;

      case 5:

        System.out.println("May");

        break;

      case 6:

        System.out.println("Jun");

        break;

     default: System.out.println("The next half");

} }

}

The output of the above Java code will be:

Jun

Nested Switch Case Statement

A switch can be used as a component of the statement chain of an external switch. A switch statement establishes one's own block, ensuring that there is no possibility of any conflicts between both the case variables inside the inner switch and in the outer switch.

Let us see a Java program below to understand nested switch cases in a better manner:

public class HKR {

 public static void main(String[] args)

 {

  String Branch = "Computer Science";

  int yr = 2;

  switch (yr) {


  case 1:

   System.out.println(

    "The selective courses are: English and Algebra");

   break;

  case 2:

   switch (Branch) {


   case "Computer Science":

   case "ECE":

    System.out.println(

     "The selective courses are: Artificial Intelligence and Machine Learning");

    break;


   case "CCE":

    System.out.println(

     "The selective courses are: Machine Engineering");

    break;

   default:


    System.out.println(

     "The selective course is: Optimization");

   }

  }

 }

}

The output of the above Java code will be:

The selective courses are: Artificial Intelligence and Machine Learning

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Conclusion

In this article, we have talked about switch cases in Java. A conditional statement in Java that tests many values and produces one result is known as a switch statement. Cases are the various values that are checked. We have also discussed the rules related to switch cases along with their working. We have also demonstrated several examples related to Java’s switch case statements. 

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