Java Tutorial/Statement Control/Switch Statement
Содержание
Execute the same statements for several different case labels
<source lang="java">
public class MainClass {
public static void main(String[] args) {
char yesNo = "N";
switch(yesNo) {
case "n": case "N":
System.out.println("No selected");
break;
case "y": case "Y":
System.out.println("Yes selected");
break;
}
}
}</source>
No selected
Free Flowing Switch Statement Example
<source lang="java">
public class Main {
public static void main(String[] args) {
int i = 0;
switch (i) {
case 0:
System.out.println("i is 0");
case 1:
System.out.println("i is 1");
case 2:
System.out.println("i is 2");
default:
System.out.println("Free flowing switch example!");
}
}
} /* i is 0 i is 1 i is 2 Free flowing switch example!
- /</source>
Nested Switch Statements Example
<source lang="java">
public class Main {
public static void main(String[] args) {
int i = 0;
switch (i) {
case 0:
int j = 1;
switch (j) {
case 0:
System.out.println("i is 0, j is 0");
break;
case 1:
System.out.println("i is 0, j is 1");
break;
default:
System.out.println("nested default case!!");
}
break;
default:
System.out.println("No matching case found!!");
}
}
} //i is 0, j is 1</source>
Switch statement with enum
<source lang="java">
public class MainClass {
enum Choice { Choice1, Choice2, Choice3 }
public static void main(String[] args) {
Choice ch = Choice.Choice1;
switch(ch) {
case Choice1:
System.out.println("Choice1 selected");
break;
case Choice2:
System.out.println("Choice2 selected");
break;
case Choice3:
System.out.println("Choice3 selected");
break;
}
}
}</source>
Choice1 selected
The switch Statement
- An alternative to a series of else if is the switch statement.
- The switch statement allows you to choose a block of statements to run from a selection of code, based on the return value of an expression.
- The expression used in the switch statement must return an int or an enumerated value.
The syntax of the switch statement is as follows.
<source lang="java">
switch (expression) { case value_1 :
statement (s);
break;
case value_2 :
statement (s);
break;
.
.
.
case value_n :
statement (s);
break;
default:
statement (s);
}</source>
The switch Statement: a demo
<source lang="java">
public class MainClass {
public static void main(String[] args) {
int choice = 2;
switch (choice) {
case 1:
System.out.println("Choice 1 selected");
break;
case 2:
System.out.println("Choice 2 selected");
break;
case 3:
System.out.println("Choice 3 selected");
break;
default:
System.out.println("Default");
break;
}
}
}</source>
Choice 2 selected
