Exercise Optionals 03

Author: SteffenLm

.github/workflows/format.yml

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+name: format and commit all java files
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - 'exercises/**'
+      - 'solutions/**'
+
+jobs:
+  formatting:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v3
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+      - uses: axel-op/googlejavaformat-action@v3

.gitignore

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+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*

BeerBottle.java

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+public class BeerBottle extends Bottle {
+
+  public void chugALug() {
+    System.out.println("Ex und Hopp");
+  }
+}

Bottle.java

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+public abstract class Bottle {}

Crate.java

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+public class Crate<T> {
+
+  private T box1;
+  private T box2;
+  private T box3;
+  private T box4;
+  private T box5;
+  private T box6;
+
+  public void insertBottle(T bottle, int box) throws CrateIndexOutOfBoundsException {
+    if (box < 1 || box > 6) {
+      throw new CrateIndexOutOfBoundsException();
+    }
+
+    switch (box) {
+      case 1 -> box1 = bottle;
+      case 2 -> box2 = bottle;
+      case 3 -> box3 = bottle;
+      case 4 -> box4 = bottle;
+      case 5 -> box5 = bottle;
+      case 6 -> box6 = bottle;
+    }
+  }
+
+  public T takeBottle(int box) throws CrateIndexOutOfBoundsException {
+    if (box < 1 || box > 6) {
+      throw new CrateIndexOutOfBoundsException();
+    }
+
+    return switch (box) {
+      case 1 -> box1;
+      case 2 -> box2;
+      case 3 -> box3;
+      case 4 -> box4;
+      case 5 -> box5;
+      default -> box6;
+    };
+  }
+}

CrateIndexOutOfBoundsException.java

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+public class CrateIndexOutOfBoundsException extends Exception {
+
+  private static final long serialVersionUID = 1L;
+
+  public CrateIndexOutOfBoundsException() {
+    super("Der angegebene Index befindet sich ausserhalb der Grenzen");
+  }
+}

Exercise.java

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+public class Exercise {
+
+  public static void main(String[] args) {
+    Crate<Bottle> crate = new Crate<Bottle>();
+
+    try {
+      crate.insertBottle(new BeerBottle(), 1);
+      crate.insertBottle(new BeerBottle(), 2);
+      crate.insertBottle(new BeerBottle(), 3);
+      crate.insertBottle(new WineBottle(), 4);
+      crate.insertBottle(new WineBottle(), 5);
+      crate.insertBottle(new WineBottle(), 6);
+
+      if (crate.takeBottle(3) instanceof BeerBottle beerBottle) {
+        beerBottle.chugALug();
+      }
+    } catch (CrateIndexOutOfBoundsException e) {
+      System.err.println(e.getMessage());
+    }
+  }
+}

WineBottle.java

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+public class WineBottle extends Bottle {}