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Commit ba98451

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Add exception handling to Java tutorial
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‎Java/01 Java - Introduction (WIP).md‎

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@@ -993,6 +993,8 @@ int found_index = Arrays.binarySearch(nums, 5); // Binary search!
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Arrays.equals(copied_nums, nums); // Array equality!
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Arrays.sort(nums); // In-place sort!
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Arrays.toString(nums); // Get string representation
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```
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And lots more! Press `Ctrl-Space` in IntelliJ after typing `Arrays.` to see the list! Then you can use `Ctrl-Q` to see the relevant javadocs.
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### Methods (Functions)
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### Sleeping
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Delay your program flow!
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Simple use `Thread.sleep()`! But ensure that you append your method signature with `throws InterruptedException`!
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```java
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public class SleepMessages {
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public static void main(String args[]) throws InterruptedException {
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String theBreathOfSong[] = {
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"Within a land of Wind and Sky",
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"A Dragon spreads his wings",
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"He flies on through strife-stricken Fields",
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"Takes Pause",
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"And soars to Dawn"
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};
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for (int i = 0; i < theBreathOfSong.length; i++) {
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Thread.sleep(1000); // Pause for 1 second
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System.out.println(importantInfo[i]);
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}
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}
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}
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```
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### Exception Handling
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In the previous section we saw that we said that the `main()` function could throw an `InterruptedException`. This section is all about handling exceptions such as that!
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**General Exception Handling with `try catch`**
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```java
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public class Main {
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public static void main(String[ ] args) {
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try {
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int[] myNumbers = {1, 2, 3};
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System.out.println(myNumbers[10]);
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} catch (Exception e) {
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System.out.println("Something went wrong.");
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}
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}
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}
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```
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You can also use `finally` to run things at the end even if an exception was caught!
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```java
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public class Main {
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public static void main(String[] args) {
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try {
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int[] myNumbers = {1, 2, 3};
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System.out.println(myNumbers[10]);
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} catch (Exception e) {
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System.out.println("Something went wrong.");
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} finally {
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System.out.println("The 'try catch' is finished.");
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}
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}
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}
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```
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**Throw and Throws**
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Use `throw` to throw an exception.
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```java
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throw new ArithmeticException("/ by zero");
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```
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Use `throws` to indicate that the method it is attached to **might** throw some exception. The caller to the method has the responsibility of handling the exception in a `try catch` block.
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```java
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type method_name(parameters) throws exception_list {}
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// exception_list is a comma separated list of all the exceptions which a method might throw.
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```
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### Assertions
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Mandate that some statement evaluates to true, otherwise, throw an assertion error.
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This is usually used for test cases!
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```java
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assert assertion_expression : "printed string if false"
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```
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### Methods (Functions) [This should be moved to another function specific tutorial section]
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Methods are just functions within a class. But because everything in Java must be within a class, every Java function is a method.
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### Java Handing
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2.1 [Comments](#2.1)
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2.2 [Importing Libraries](#2.2)
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2.3 [Hello World!](#2.3)
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2.4 [Running Programs](#2.4)
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2.5 [Variables and Data Types](#2.5)
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2.6 [Ouputting Variables and Variable Info](#2.6)
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2.7 [Casting (Type Conversion)](#2.7)
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2.8 [Arithmetic Operations](#2.8)
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2.9 [Conditionals](#2.9)
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2.10 [Ternary Operators](#2.10)
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2.11 [Switch Cases](#2.11)
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2.12 [Arrays](#2.12)
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2.13 [Multi-Dimensional Arrays](#2.13)
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2.14 [Strings](#2.14)
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2.15 [User Input](#2.15)
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2.16 [For Loops](#2.16)
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2.17 [While Loops](#2.17)
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2.18 [Do While Loops](#2.18)
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2.19 [Vectors](#2.19)
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2.20 [Printf](#2.20)
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2.21 [Argc and Argv](#2.21)
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2.22 [Exception Handling](#2.22)
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2.22 [Scopes](#2.23)
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```
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. .

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