mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-11-09 18:50:34 -05:00
112 lines
2.1 KiB
Markdown
112 lines
2.1 KiB
Markdown
# 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 `float`s
|
|
|
|
### Syntax
|
|
|
|
```java
|
|
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
|
|
|
|
```java
|
|
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
|
|
|
|
```java
|
|
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
|
|
|
|
```java
|
|
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
|
|
|
|
```java
|
|
String output = "";
|
|
if (movieRating > 4) {
|
|
output = "Fan favorite";
|
|
} else {
|
|
output = "Alright";
|
|
}
|
|
```
|
|
|
|
Is equivalent to
|
|
|
|
```java
|
|
String output = "";
|
|
output = (movieRating > 4)? "Fan favorite": "Alright";
|
|
```
|
|
|
|
### Another Example
|
|
|
|
```java
|
|
double shipping;
|
|
if (isPrimeMember) {
|
|
shipping = 0;
|
|
} else {
|
|
shipping = 3.99;
|
|
}
|
|
```
|
|
|
|
Is equivalent to
|
|
|
|
```java
|
|
double shipping = (isPrimeMember)? 0: 3.99;
|
|
```
|
|
|