also known switch statement select statement, the following format
The switch statement format:
![](https://img2018.cnblogs.com/i-beta/1401526/201911/1401526-20191115033123605-1363742281.png)
Implementation process
- First, calculate the value of the expression
- Secondly, compare and order case, if there is a corresponding value, will execute the corresponding statement in the process of implementation, it encounters a break will end.
- Finally, if the case were all expressions and values do not match, it will execute the default statement body part, and the program ends off.
Code execution flow as shown below
![](https://img2018.cnblogs.com/i-beta/1401526/201911/1401526-20191115033300464-1454670221.png)
Code Example
Package demo03_Switch; public class Demo01Switch { public static void main (String [] args) { // definition of variables, of the week is determined int WEEKDAY =. 1 ; // Switch statement to achieve select Switch (WEEKDAY) { Case . 1 : the System.out. println ( "Monday" ); BREAK ; Case 2 : System.out.println ( "Tuesday" ); BREAK ; Case 3 : System.out.println ( "Wednesday" ); BREAK ; Case 4 : System.out.println ( "Thursday" ); BREAK ; Case 5 : System.out.println ( "Friday" ); BREAK ; Case 6 : System. out.println ( "Saturday" ); BREAK ; Case 7 : System.out.println ( "Sunday" ); break; default: System.out.println("错误"); break; } } }
The result of code execution
Note the use of the switch statement:
- The latter case a plurality of values can not be repeated.
- Switch parentheses behind which only the following data types: basic data types: byte / short / char / int reference Data Type: String String, enum enum
- The switch statement format can be very flexible: before and after the order can be reversed, and break statement can also be omitted. case of penetration : in a switch statement, if the latter case is not writing break, will appear penetration phenomenon, which is not a value judgment in the case, run directly back, until it encounters a break, or the entire switch End. Because of penetrating case, you must write on the break.