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Switch When

We can make switch statements into if-then-else statements.

switch(num) {
  case 0: System.out.println("zero");
    break;
  case 1: System.out.println("one");
    break;
  default: System.out.println("neither");
}

// translated to if else...
if (num == 0) {
  System.out.println("zero");
}
else if (num == 1) {
  System.out.println("one");
}
else {
  System.out.println("neither");
}
Since switch and if statements are similar, when do we use a switch over an if?

switch is useful when we have a discrete, constant set of cases, like the buttons on a remote control.

discrete

Individually separate and distinct.

switch(buttonPressed){
  case "0":
    //...
    break;
  case "1":
    //...
    break;
}

Use if when you need to compare against something that varies, like comparing if a number is in a range of values.

if (value >= 18 && value <= 34) {
  //...
}
Use switch if you need fall through.

Drill

Switch/src/examples/PrintDots.java * Examine and run the program.

(We will learn better ways to create this kind of output. This example just takes advantage of fall through.)

Practice Exercise

You will use if much, much more than switch.

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