altoslib/altosuilib: Fix equals methods, add hashCode

Whenever we use a class as a HashMap key, that class needs to override
the equals(Object) and hashCode() methods. Otherwise, the hash table
won't work right.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/altoslib/AltosPointInt.java b/altoslib/AltosPointInt.java
index 5d884391..a7dd00f7 100644
--- a/altoslib/AltosPointInt.java
+++ b/altoslib/AltosPointInt.java
@@ -20,7 +20,19 @@ package org.altusmetrum.altoslib_7;
 public class AltosPointInt {
 	public int	x, y;
 
-	public boolean equals(AltosPointInt n) {
+	public int hashCode() {
+		return  x ^ y;
+	}
+
+	public boolean equals(Object o) {
+		if (o == null)
+			return false;
+
+		if (!(o instanceof AltosPointInt))
+			return false;
+
+		AltosPointInt n = (AltosPointInt) o;
+
 		return n.x == x && n.y == y;
 	}