Live code Follow-Along

src/main/java/io/github/auberonedu/equalsLivecode/App.java

@@ -14,13 +14,33 @@ public static void main(String[] args) {
         Centroid locA = new Centroid(4, 9, "Salamander");
         Centroid locB = new Centroid(4, 9, "Salamander");
 
-        System.out.println("Result of locA == locB " + (locA == locB));
-        System.out.println("Result of locA.equals(locB) " + locA.equals(locB));
+        System.out.println("Result of locA == locB " + (locA == locB)); // comparing reference
+        System.out.println("Result of locA.equals(locB) " + locA.equals(locB)); // hopefully value equality (if rewritten in Centroid.java)
 
-        videoDemo();
+        Set<Centroid> centroids = new HashSet<>();
+        centroids.add(locA);
+        centroids.add(locB);
+
+        System.out.println(locA.hashCode());
+        System.out.println(locB.hashCode());
+
+        System.out.println(centroids.contains(locB));
+
+
+        System.out.println("--- Records ---");
+        Location a = new Location(5, 1, "food");
+        Location b = new Location(5, 1, "food");
+
+        System.out.println(a.equals(b));
+        System.out.println(a.hashCode());
+        System.out.println(b.hashCode());
+
+
+        //videoDemo();
     }
 
     // We will look at this a bit later in the livecode, please ignore for first part
+
     public static void videoDemo() {
         List<char[][]> video = List.of(
             // Frame 0: Salamander is at [2, 3] (all locations in [row, column] format)
@@ -94,5 +114,5 @@ public static void videoDemo() {
         boolean hasOverlap = !Collections.disjoint(salamanderLocations, foodLocations);
         System.out.println("Do the salamander locations overlap with the food locations: " + hasOverlap);
     }
-
+    
 }

src/main/java/io/github/auberonedu/equalsLivecode/Centroid.java

@@ -22,4 +22,57 @@ public int getC() {
     public String getName() {
         return name;
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + r;
+        result = prime * result + c;
+        result = prime * result + ((name == null) ? 0 : name.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        Centroid other = (Centroid) obj;
+        if (r != other.r)
+            return false;
+        if (c != other.c)
+            return false;
+        if (name == null) {
+            if (other.name != null)
+                return false;
+        } else if (!name.equals(other.name))
+            return false;
+        return true;
+    }
+
+
+    // @Override
+    // // allowed to access private fields of different objects in the same class
+    // public boolean equals(Object o) {
+    //     if (o == null) return false; // checking if o is null -- false
+    //     if (getClass() != o.getClass()) return false; // checking if o is not a Centroid -- false
+
+    //     Centroid other = (Centroid) o; // casting o as a Centroid
+
+    //     // compare fields
+    //     if(r != other.r) return false;
+    //     if(c != other.c) return false;
+    //     if(name == null){
+    //         if (other.name == null) return true;
+    //         if (other.name != null) return false;
+    //     }
+    //     if(!name.equals(other.name)) return false;
+
+    //     return true;
+
+    // }
 }

src/main/java/io/github/auberonedu/equalsLivecode/Location.java

@@ -0,0 +1,4 @@
+package io.github.auberonedu.equalsLivecode;
+
+public record Location(int x, int y, String label) {
+}