Day 1 Final

SimonHGR · SimonHGR · commit 01c596502ff6 · 2021-09-08T17:58:05.000-06:00
diff --git a/Capture 8.png b/Capture 8.png
diff --git a/src/main/java/students2/School.java b/src/main/java/students2/School.java
@@ -6,18 +6,23 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.function.Consumer;
 
+@FunctionalInterface
 interface Criterion<E> {
   boolean test(E s);
+//  void doStuff();
 }
+//
+//interface Something<E> {
+//  void doSomething(E e);
+//}
 
-interface Something<E> {
-  void doSomething(E e);
-}
-
-class PrintSomething implements Something<Student> {
+//class PrintSomething implements Something<Student> {
+class PrintSomething implements Consumer<Student> {
   @Override
-  public void doSomething(Student student) {
+//  public void doSomething(Student student) {
+  public void accept(Student student) {
     System.out.println("> " + student);
   }
 }
@@ -29,9 +34,11 @@ public class School {
 //    }
 //    System.out.println("---------------------------");
 //  }
-  public static <E> void withEvery(Iterable<E> ls, Something<E> someObject) {
+//  public static <E> void withEvery(Iterable<E> ls, Something<E> someObject) {
+  public static <E> void withEvery(Iterable<E> ls, Consumer<E> someObject) {
     for (E s : ls) {
-      someObject.doSomething(s);
+//      someObject.doSomething(s);
+      someObject.accept(s);
     }
   }
 
@@ -58,7 +65,7 @@ public static void main(String[] args) {
 //    });
 
     // show smart students
-//    showAll(getByCriterion(roster, ???));
+    withEvery(getByCriterion(roster, s -> s.getGpa() > 3.0), s -> System.out.println(s));
 
     // show unenthusiastic students
 //    showAll(getByCriterion(roster, ???));
diff --git a/src/main/java/superiterable/SuperIterable.java b/src/main/java/superiterable/SuperIterable.java
@@ -0,0 +1,50 @@
+package superiterable;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+public class SuperIterable<E> implements Iterable<E> {
+  private Iterable<E> self;
+
+  public SuperIterable(Iterable<E> self) {
+    this.self = self;
+  }
+
+//  public void withEvery(SuperIterable<E> this, Consumer<E> someObject) {
+// This is "forEach"
+//  public void withEvery(Consumer<E> someObject) {
+//    for (E s : this.self) {
+//      someObject.accept(s);
+//    }
+//  }
+
+  public SuperIterable<E> filter(SuperIterable<E>this, Predicate<E> crit) {
+    List<E> res = new ArrayList<>();
+    for (E s : this.self) {
+      if (crit.test(s)) {
+        res.add(s);
+      }
+    }
+    return new SuperIterable<>(res);
+  }
+
+
+  // This type of wrapper (if it conforms to some math rules)
+  // this is called (in functional programming) a "functor"
+  public <F> SuperIterable<F> map(Function<E, F> op) {
+    List<F> res = new ArrayList<>();
+    for (E s : this.self) {
+      F f = op.apply(s);
+      res.add(f);
+    }
+    return new SuperIterable<>(res);
+  }
+
+  @Override
+  public Iterator<E> iterator() {
+    return self.iterator();
+  }
+}
diff --git a/src/main/java/superiterable/UseSuperIterable.java b/src/main/java/superiterable/UseSuperIterable.java
@@ -0,0 +1,23 @@
+package superiterable;
+
+import java.util.List;
+
+public class UseSuperIterable {
+  public static void main(String[] args) {
+    SuperIterable<String> sis = new SuperIterable<>(List.of("Fred", "Jim", "Sheila"));
+    for (String s : sis) {
+      System.out.println("> " + s);
+    }
+
+//    sis.withEvery(s -> System.out.println("I found the name: " + s));
+    sis.forEach(s -> System.out.println("I found the name: " + s));
+
+//    SuperIterable<String> longs = sis.getByCriterion(s -> s.length() > 3);
+//    longs.withEvery(s -> System.out.println("Long: " + s));
+
+    sis
+        .filter(s -> s.length() > 3)
+        .map(s -> s.toUpperCase())
+        .forEach(s -> System.out.println("Long: " + s));
+  }
+}
