Challenges

Author: bowbahdoe

src/SUMMARY.md

@@ -774,7 +774,7 @@ Make them do one. -->
   - [Get a Constructor](./reflection/get_a_constructor.md)
   - [Get all Constructors](./reflection/get_all_constructors.md)
   - [Invoke a Constructor](./reflection/invoke_a_constructor.md)
-
+  - [Challenges](./reflection/challenges.md)
 - [Annotations](./annotations.md)
   - [Declaration](./annotations/declaration.md)
   - [Usage](./annotations/usage.md)
@@ -785,6 +785,7 @@ Make them do one. -->
   - [@Retention](./annotations/retention.md)
   - [Reflective Access](./annotations/reflective_access.md)
   - [@Override](./annotations/override.md)
+  - [Challenges](./annotations/challenges.md)
   <!--  - [@Deprecated](./annotations/deprecated)
   - [@Repeatable]()Note: When doing javadoc, write about @Documented -->
 
@@ -805,6 +806,7 @@ Make them do one. -->
   - [Interface Extension](./interfaces_ii/interface_extension.md)
   - [Static Methods](./interfaces_ii/static_methods.md)
   - [Static Fields](./interfaces_ii/static_fields.md)
+  - [Challenges](./interfaces_ii/challenges.md)
 - [Class Extension](./class_extension.md)
   - [Extend a Class](./class_extension/extend_a_class.md)
   - [Inheritance](./class_extension/inheritance.md)
@@ -815,6 +817,7 @@ Make them do one. -->
   - [Relation to Interfaces](./class_extension/relation_to_interfaces.md)
   - [Relation to Encapsulation](./class_extension/relation_to_encapsulation.md)
   - [Final Classes](./class_extension/final_classes.md)
+  - [Challenges](./class_extension/challenges.md)
 
 
 # Data Types IX
@@ -825,6 +828,7 @@ Make them do one. -->
   - [long](./niche_numerics/long.md)
   - [Unsigned Operations](./niche_numerics/unsigned_operations.md)
   - [float](./niche_numerics/float.md)
+  - [Challenges](./niche_numerics/challenges.md)
 
 # Projects
 

src/annotations/challenges.md

@@ -0,0 +1,48 @@
+# Challenges
+
+
+Remember the rules for this are
+
+- Try to use only the information given up to this point in this book.
+- Try not to give up until you've given it a solid attempt
+
+## Challenge 1.
+
+Declare your own `@Favorite` and `@LeastFavorite`
+annotations.
+
+Use them to mark the code you have written so far that is your
+favorite and the code that is your least favorite.
+
+## Challenge 2.
+
+Declare a `@LoFi` annotation. It should have an element for the `author`
+and another element for the `song` that you were listening to on
+the "[24/7 Lofi Hip Hop Radio - Beats to Relax/Study To](https://www.youtube.com/watch?v=jfKfPfyJRdk)"
+stream when you were writing the annotated code.
+
+Chill out to some tunes, write some code, and use that annotation.
+
+## Challenge 3.
+
+Write a method that takes in an `Object`. Use reflection to print out the values in that `Object`'s
+declared fields. Skip any that are non-public but also any marked with a `@Skip` annotation
+that you should also define.
+
+```java
+// CODE HERE
+
+class Table {
+    public boolean flowerPot = true;
+    public String scissors = "green";
+
+    @Skip
+    public String cat = "tabby";
+}
+
+class Main {
+    void main() {
+        // CODE HERE
+    }
+}
+```

src/class_extension/challenges.md

@@ -0,0 +1,128 @@
+# Challenges
+
+Remember the rules for this are
+
+- Try to use only the information given up to this point in this book.
+- Try not to give up until you've given it a solid attempt
+
+## Challenge 1.
+
+Write a class called `Tree` which extends `ArrayList<Apple>`.
+
+Add a `.grow()` method which adds two apples to itself
+of arbitrary size.
+
+```java,editable
+record Apple(double size) {}
+
+// CODE HERE
+
+class Main {
+    Tree tree = new Tree();
+    tree.grow();
+    tree.grow();
+
+    // You should have inherited the toString
+    // from ArrayList
+    IO.println(tree);
+
+    // As well as all the other methods
+    tree.add(new Apple(100));
+    IO.println(tree);
+
+    for (var apple : tree) {
+        IO.println(apple);
+    }
+}
+```
+
+## Challenge 2.
+
+Rewrite your `Tree` class from above to instead extend `AbstractList<Apple>`.
+You can find the documentation for `AbstractList` [here](https://docs.oracle.com/javase/8/docs/api/java/util/AbstractList.html).
+
+## Challenge 3.
+
+Make an `abstract` class called `Fish`. It should provide a method named
+`swim` and a method named `howLongSwim` that returns how many times `swim`
+was called.
+
+This 
+```java
+// CODE HERE
+
+class Dory extends Fish {
+    void justKeepSwimming() {
+        IO.println("Just keep swimming");
+        this.swim();
+
+        IO.println("Just keep swimming");
+        this.swim();
+
+        IO.println("Just keep swimming");
+        this.swim();
+
+        IO.println("swimming");
+        this.swim();
+
+        IO.println("swimming");
+        this.swim();
+    }
+}
+
+class Main {
+    void main() {
+        var dory = new Dory();
+        dory.justKeepSwimming();
+
+        IO.println(dory.howLongSwim());
+    }
+}
+```
+
+## Challenge 4.
+
+Make the field you use to track how many times 
+the fish swam `protected`. Also make the `swim`
+method `protected` and `abstract`.
+
+Write comments in your code such that the "contract"
+between your class and classes implementing it
+is that they must keep the `swam` field up to date.
+
+This 
+```java
+// CODE HERE
+
+class Dory extends Fish {
+
+
+    @Override
+    void swim() {
+        IO.println("Just keep swimming");
+        this.swam++;
+
+        IO.println("Just keep swimming");
+        this.swam++;
+
+        IO.println("Just keep swimming");
+        this.swam++;
+
+        IO.println("swimming");
+        this.swam++;
+
+        IO.println("swimming");
+        this.swam++;
+    }
+}
+
+class Main {
+    void main() {
+        var dory = new Dory();
+        dory.swim();
+
+        IO.println(dory.howLongSwim());
+    }
+}
+```
+

src/compilation/javac.md

@@ -34,8 +34,3 @@ output/
     Main$1.class
     Main$Thing.class
 ```
-
-To compile multiple files you need to list every `.java` file
-one after another.
-
-```

src/interfaces_ii/challenges.md

@@ -0,0 +1,100 @@
+# Challenges
+
+Remember the rules for this are
+
+- Try to use only the information given up to this point in this book.
+- Try not to give up until you've given it a solid attempt
+
+## Challenge 1.
+
+Create an interface named `TabbyCat`. It should 
+extend the provided `Cat` interface and provide
+a `lounge` method along with a default implementation of that
+method.
+
+```java
+interface Cat {
+    void purr();
+}
+
+// CODE HERE
+
+class Garfield implements TabbyCat {
+    @Override
+    public void purr() {
+        IO.println("mmmm lasagna");
+    }
+}
+
+class Main {
+    void main() {
+        TabbyCat c = new Garfield();
+        // Should come in via a default method.
+        c.lounge();
+    }
+}
+```
+
+## Challenge 2.
+
+Add a static field to the `Cat` interface
+which indicates the healthy amount of lasagna for a cat to 
+consume.[^zero]
+
+```java
+interface Cat {
+    void purr();
+}
+
+class Main {
+    void main() {
+        // 0
+        IO.println(Cat.HEALTHY_AMOUNT_OF_LASAGNA);
+    }
+}
+```
+
+## Challenge 3.
+
+Put a static method on the `Cat` interface named `garfield"
+which returns an instance of `TabbyCat`.
+
+```java,no_run
+public interface Cat {
+    // CODE HERE
+}
+```
+
+```java,no_run
+public interface TabbyCat extends Cat {
+    // CODE FROM PREVIOUS CHALLENGES
+}
+```
+
+```java,no_run
+class Garfield implements TabbyCat {
+    @Override
+    public void purr() {
+        IO.println("mmmm lasagna");
+    }
+}
+```
+
+```java
+public class Main {
+    void main() {
+        TabbyCat tc = Cat.garfield();
+        tc.lounge();
+    }
+}
+```
+
+Note that this gives you a way to expose a `Garfield` instance
+to other packages, even if the `Garfield` class itself
+is `non-public`.[^unrunnable]
+
+[^zero]: Zero, it can literally kill them.
+
+[^unrunnable]: Apologies for the inconvenience. To make the point about
+package visibility I had to make the code in browser non runnable
+or editable. You should be able to manage at this point though.