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112 lines
2.1 KiB
Markdown
112 lines
2.1 KiB
Markdown
# Lecture for February 8th
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##Switch Statements
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Another way to perform multiway branching. Comparing a variable and constant values (`String`, `int`, `char`)
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Switch statements cannot be used with `boolean`, `double`, or `float`s
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### Syntax
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```java
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switch (variable) {
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case value1:
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// Do something
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break;
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case value2:
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// Do something else
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break;
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//...
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default:
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// If all else fails do this
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break;
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}
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```
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`case` is a reserved word that means "when our variable in consideration is equal to..."
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If you forget the `break` keyword, then the program will keep doing the work of all the statements until it hits a `break` keyword.
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### Example Switch Syntax
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```java
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switch (birthday) {
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case 1:
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birthstone = "garnet";
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break;
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case 2:
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birthstone = "amethyst";
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break;
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// ....
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default:
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System.out.println("Not valid");
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break;
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}
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```
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## Comparing Strings Relationally
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Comparing strings are based on the ASCII value of characters
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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.
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To compare strings use the `compareTo()` method. Here is the format of the call
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```java
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str1.compareTo(str2)
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```
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This returns a *negative number* when `str1` is less than `str2`
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This returns `0` when `str1` is equal to `str1`
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This returns a *positive number* when `str1` is greater than `str2`
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### Example
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```java
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String a = "apple";
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String b = "banana";
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int x = a.compareTo(b); // x = -1
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int y = b.compareTo(a); // y = 1
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```
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## Ternary Operator
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With a ternary operator, you can shorten statements where a value is determined by an if statement
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```java
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String output = "";
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if (movieRating > 4) {
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output = "Fan favorite";
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} else {
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output = "Alright";
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}
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```
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Is equivalent to
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```java
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String output = "";
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output = (movieRating > 4)? "Fan favorite": "Alright";
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```
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### Another Example
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```java
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double shipping;
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if (isPrimeMember) {
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shipping = 0;
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} else {
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shipping = 3.99;
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}
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```
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Is equivalent to
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```java
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double shipping = (isPrimeMember)? 0: 3.99;
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```
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