Java switch case with examples

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Last Updated on 29 March 2020   |   Print  Email


This article helps you understand and use the switch case construct in Java with code examples.

The switch-case construct is a flow control structure that tests value of a variable against a list of values. Syntax of this structure is as follows:

switch (expression) {
    case constant_1:
        // statement 1
        break;
    case constant_2:
        // statement 2
        break;
    case constant_3:
        // statement 3
        break;
    //...
    case constant_n:
        // statement n
        break;
    default:
        // if all the cases do not match
}
 

Some Rules about switch-case construct:

    •           The expression is a variable or an expression which must be evaluated to one of the following types:
      •       Primitive numbers: byte, short, char and int
      •       Primitive wrappers: Byte, Short, Characterand Integer.
      •       Enumerated types (enum type).
      •       String literals (since Java 1.7)
    •           The constant_1, constant_2, constant_3, …, constant_n must be a constant or literals of the allowed types.
    •           Each case is tested from top to bottom, until a case is matched and a break statement is found.
    •           If a case matches the expression, the statements block after the case clause are executed, until a break statement is reached.

    •           It is not required that each case must have a corresponding break statement. If a matching case block does not have a break statement, the execution will fall through the next case block, until a first break statement is reached or end of switch statement is encountered.

    •           The statements block after default will be executed if there is no matching case found.


Some Java switch-case examples:

          The following example shows a switch statement that tests for an integer variable. It products the output: The number is Three

int number = 3;

String text = "";

switch (number) {
    case 1:
        text = "One";
        break;
    case 2:
        text = "Two";
        break;
    case 3:
        text = "Three";
        break;
    default:
        text = "Other number";
}

System.out.println("The number is: " + text);
 

 The following example shows a switch statement that tests for a String variable, without a default block. It will output: The distance from earth to Jupiter is: 4

String planet = "Jupiter";

long distanceFromEarth = 0;

switch (planet) {
    case "Mars":
        distanceFromEarth = 3;
        break;
    case "Saturn":
        distanceFromEarth = 5;
        break;
    case "Jupiter":
        distanceFromEarth = 4;
        break;
    case "Venus":
        distanceFromEarth = 1;
        break;
}

System.out.println("The distance from earth to " + planet + " is: " + distanceFromEarth);
 

          The following example shows a switch statement that tests for an enum type, Priority. It will output the result: Task priority: 3

Priority priority = Priority.HIGH;

int taskPriority = 0;

switch (priority) {
    case LOW:
        taskPriority = 1;
        break;
    case NORMAL:
        taskPriority = 2;
        break;
    case HIGH:
        taskPriority = 3;
        break;
    case SEVERE:
        taskPriority = 4;
        break;
}

System.out.println("Task priority: " + taskPriority);
The enum Priority is declared as follows:

public enum Priority { LOW, NORMAL, HIGH, SEVERE }
 

From Java 14, you can use switch block as an expression. For example:

int taskPriority = switch (priority) {
    case LOW -> 1;
    case NORMAL -> 2;
    case HIGH -> 3;
    case SEVERE -> 4;
};

System.out.println("Task priority: " + taskPriority);
Learn more: Java 14: Switch Expressions Enhancements Examples

 

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About the Author:

is certified Java programmer (SCJP and SCWCD). He started programming with Java in the time of Java 1.4 and has been falling in love with Java since then. Make friend with him on Facebook and watch his Java videos you YouTube.



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