From b1317e5e62bb044cd8a676cb3fc2da86e9922caf Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Thu, 28 Jul 2016 16:36:17 -0400
Subject: Added debugging aid for finding single instantiation violations.

Also, fixed a single instantiation violation into BoundLazyPair
---
 .../src/main/java/bjc/utils/data/SingleSupplier.java | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

(limited to 'BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java')

diff --git a/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java b/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java
index 016f492..989f1a5 100644
--- a/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java
+++ b/BJC-Utils2/src/main/java/bjc/utils/data/SingleSupplier.java
@@ -9,6 +9,10 @@ public class SingleSupplier<T> implements Supplier<T> {
 
 	private long		id;
 
+	// This is bad practice, but I want to know where the single
+	// instantiation was, in case of duplicate initiations
+	private Exception	instSite;
+
 	private static long	nextID	= 0;
 
 	public SingleSupplier(Supplier<T> supp) {
@@ -22,13 +26,25 @@ public class SingleSupplier<T> implements Supplier<T> {
 	@Override
 	public T get() {
 		if (gotten == true) {
-			throw new IllegalStateException(
+			IllegalStateException isex = new IllegalStateException(
 					"Attempted to get value more than once"
-							+ " from single supplier #" + id);
+							+ " from single supplier #" + id
+							+ ". Previous instantiation below.");
+
+			isex.initCause(instSite);
+
+			throw isex;
 		}
 
 		gotten = true;
 
+		try {
+			throw new IllegalStateException(
+					"Previous instantiation here.");
+		} catch (IllegalStateException isex) {
+			instSite = isex;
+		}
+
 		return source.get();
 	}
 }
-- 
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