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, 7 insertions, 4 deletions

diff --git a/altosuilib/AltosBTDevice.java b/altosuilib/AltosBTDevice.java
index 76221df2..d6eed64d 100644
--- a/altosuilib/AltosBTDevice.java
+++ b/altosuilib/AltosBTDevice.java
@@ -104,17 +104,20 @@ public class AltosBTDevice extends altos_bt_device implements AltosDevice {
 		return false;
 	}
 
+	public int hashCode() {
+		return getName().hashCode() ^ getAddr().hashCode();
+	}
+
 	public boolean equals(Object o) {
+		if (o == null)
+			return false;
+
 		if (!(o instanceof AltosBTDevice))
 			return false;
 		AltosBTDevice other = (AltosBTDevice) o;
 		return getName().equals(other.getName()) && getAddr().equals(other.getAddr());
 	}
 
-	public int hashCode() {
-		return getName().hashCode() ^ getAddr().hashCode();
-	}
-
 	public AltosBTDevice(String name, String addr) {
 		AltosUILib.load_library();
 		libaltos.altos_bt_fill_in(name, addr,this);