Lecture for February 8th

##Switch Statements

Another way to perform multiway branching. Comparing a variable and constant values (String, int, char)

Switch statements cannot be used with boolean, double, or floats

Syntax

switch (variable) {
  case value1:
    // Do something
    break;
  case value2:
    // Do something else
    break;
  //...
  default:
    // If all else fails do this
    break;
}

case is a reserved word that means “when our variable in consideration is equal to…”

If you forget the break keyword, then the program will keep doing the work of all the statements until it hits a break keyword.

Example Switch Syntax

switch (birthday) {
  case 1: 
    birthstone = "garnet";
    break;
  case 2:
    birthstone = "amethyst";
    break;
  // ....
  default:
    System.out.println("Not valid");
    break;
}

Comparing Strings Relationally

Comparing strings are based on the ASCII value of characters

Sorting strings will result in strings being in alphabetical or reverse alphabetical order. The values of the strings are compared character by character from the left with each ASCII value.

To compare strings use the compareTo() method. Here is the format of the call

str1.compareTo(str2)

This returns a negative number when str1 is less than str2

This returns 0 when str1 is equal to str1

This returns a positive number when str1 is greater than str2

Example

String a = "apple";
String b = "banana";

int x = a.compareTo(b); // x = -1

int y = b.compareTo(a); // y = 1

Ternary Operator

With a ternary operator, you can shorten statements where a value is determined by an if statement

String output = "";
if (movieRating > 4) {
  output = "Fan favorite";
} else {
  output = "Alright";
}

Is equivalent to

String output = "";
output = (movieRating > 4)? "Fan favorite": "Alright";

Another Example

double shipping;
if (isPrimeMember) {
  shipping = 0;
} else {
  shipping = 3.99;
}