Like an if/else statement, a switch statement allow you to change the flow of the program by conditionally executing code. The difference is that a switch statement can only compare the value of a primitive or string expression against pre-defined constant values.

Some keywords are useful when using a switch statement.

• switch : this keyword allows you to declare the structure of the switch. It is followed by the expression or the variable that will make the result change.
• case : you will use this to declare the differents possibilties for the result.
• break : the break keyword is very useful in order to stop the execution of the switch at the end of the wanted flow. If you forget it, the program will continue and may lead to unexpected results.
• default : as its name says, use it as a default result when no other case matchs your expression's result.

At their simplest, they test a primitive or string expression and make a decision based on its value. For example:

String direction = getDirection();
switch (direction) {
    case "left":
        goLeft();
        break;
    case "right":
        goRight();
        break;
    default:
        //otherwise
        markTime();
        break;
}