Switch Statement

/** generate a number from 1 to 12 */
int rnd = ( int ) ( Math.random * 12 ) + 1;

int num = 0;

/** start switch statement */
switch( rnd ) { // if (rnd == ...
case 0: // 0)
num = 5;
/** fall though (no break statement) */
case 1: // 1)
num += 3;
break;
case 2: // 2 ||
case 3: // 3 ||
case 4: // 4)
num = 10;
break;
default: // else
num = -5;
break;
}

they only accept an int or a char. they are very similar to if statements.. the code above is the same as:

/** generate a number from 1 to 12 */
int rnd = ( int ) ( Math.random * 12 ) + 1;

int num = 0;

if ( rnd == 0 ) {
num = 5;
num += 3;
} else if ( rnd == 1 ) {
num += 3;
} else if (( rnd == 2 ) || ( rnd == 3 ) || ( rnd == 4 )) {
num = 10;
} else {
num = -5;
}

i feel more organized using a switch statement, but you can only use switch statements with ints or chars so if your dealing with Objects, you have to use if statements.

What is going on here

public class SwitchDemo {
public static void main(String[] args) {

int month = 8;
switch (month) {
case 1: System.out.println("January"); break;
case 2: System.out.println("February"); break;
case 3: System.out.println("March"); break;
case 4: System.out.println("April"); break;
case 5: System.out.println("May"); break;
case 6: System.out.println("June"); break;
case 7: System.out.println("July"); break;
case 8: System.out.println("August"); break;
case 9: System.out.println("September"); break;
case 10: System.out.println("October"); break;
case 11: System.out.println("November"); break;
case 12: System.out.println("December"); break;
default: System.out.println("Not a month!");break;
}
}
}

You don't need to do anything special to execute a switch, it's an alternative to using an if/else statement.

Here's a simple example ...int num = 3;
switch(num){
case 1: System.out.println("num = 1!"); break;
case 2: System.out.println("num = 2!"); break;
case 3: System.out.println("num = 3!"); break;
default: System.out.println("num is unknown");
} The switch function determines what to do depending on the value of a variable.

The case value is saying if the input variable is equal to this, then execute the following code. Break tells the program to exit the switch statement. Default is executed if no case was found to be true.

Switches are not limited to integers, this is valid too:char letter = 'A';
switch(letter){
case 'A': System.out.println("You typed A"); break;
case 'B': System.out.println("You typed B"); break;
case 'C': System.out.println("You typed C"); break;
default: System.out.println("I don't know my ABC's");
}

The above code is exactly the same as if you entered the following if/else statement, it's just a matter of preference.char letter = 'A';
if(letter == 'A'){
System.out.println("You typed A");
} else if (letter == 'B'){
System.out.println("You typed B");
} else if (letter == 'C'){
System.out.println("You typed C");
} else {
System.out.println("I don't know my ABC's");
}

You can also use Enums to be the value which is compared in a switch structure.