How to use switch statement

Switch statement usage: 1. The Switch statement can only be used for integer types, enumeration types and String types, and cannot be used for floating point types and Boolean types; 2. Each case statement must be followed by a break statement , to prevent the execution of other case code blocks. If there is no break statement, the code block of the next case will continue to be executed; 3. Multiple values ​​can be matched in one case statement, separated by commas; 4. The default code in the Switch statement Blocks are optional and so on.

The switch statement is a control flow statement commonly used in programming, which allows different code blocks to be executed based on different conditions. In this article, we will introduce the use of Switch statement, as well as some best practices for using Switch statement.

The basic syntax of the Switch statement is as follows:

switch (expression) {
  case value1:
    // code block 1
    break;
  case value2:
    // code block 2
    break;
  case value3:
    // code block 3
    break;
  ...
  default:
    // code block for all other cases
    break;
}

The execution process of the Switch statement is as follows:

1. First, calculate the value of expression.

2. Then, compare the value of expression with the value after each case statement until a matching value is found.

3. Once a matching value is found, execute the corresponding code block and jump out of the Switch statement.

4. If no matching value is found, execute the default code block (if any), and then jump out of the Switch statement.

The following is a simple example that demonstrates the use of the Switch statement:

int day = 3;
String dayName;
switch (day) {
  case 1:
    dayName = "Monday";
    break;
  case 2:
    dayName = "Tuesday";
    break;
  case 3:
    dayName = "Wednesday";
    break;
  case 4:
    dayName = "Thursday";
    break;
  case 5:
    dayName = "Friday";
    break;
  case 6:
    dayName = "Saturday";
    break;
  case 7:
    dayName = "Sunday";
    break;
  default:
    dayName = "Invalid day";
    break;
}
System.out.println("Today is " + dayName);

In this example, we select the corresponding dayName based on the value of the variable day. If the value of day is 3, then "Today is Wednesday" is output.

Some notes and best practices for the Switch statement are as follows:

1. The Switch statement can only be used for integer types (byte, short, int and char), enumeration types and String types . Cannot be used for floating point types and Boolean types.

2. Each case statement must be followed by a break statement to prevent the execution of other case code blocks. If there is no break statement, the code block of the next case will continue to be executed.

3. Multiple values ​​can be matched in one case statement, separated by commas. For example: case 1, 2, 3.

4. The default code block in the Switch statement is optional and is used to handle all other unmatched situations.

5. Switch statements can be nested in other Switch statements to implement more complex logic.

To sum up, the Switch statement is a very useful control flow statement that can execute different code blocks according to different conditions. It improves code readability and maintainability. When using the Switch statement, we should pay attention to following the syntax rules and follow best practices.

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