From 70b78363ea17682c758849347d9d9b3bf33af4f3 Mon Sep 17 00:00:00 2001
From: Mike Hearn <mike@plan99.net>
Date: Tue, 21 Apr 2015 14:56:18 +0200
Subject: [PATCH] Wallet.addWatchedScripts() now lets you update a script in
 the wallet with a new creation time. Add some discussion to the Javadoc about
 this issue.

---
 core/src/main/java/org/bitcoinj/core/Wallet.java | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/org/bitcoinj/core/Wallet.java b/core/src/main/java/org/bitcoinj/core/Wallet.java
index 173483cf..7341377b 100644
--- a/core/src/main/java/org/bitcoinj/core/Wallet.java
+++ b/core/src/main/java/org/bitcoinj/core/Wallet.java
@@ -812,8 +812,11 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
     }
 
     /**
-     * Adds the given output scripts to the wallet to be watched. Outputs can be retrieved
-     * by {@link #getWatchedOutputs(boolean)}.
+     * Adds the given output scripts to the wallet to be watched. Outputs can be retrieved by {@link #getWatchedOutputs(boolean)}.
+     * If a script is already being watched, the object is replaced with the one in the given list. As {@link Script}
+     * equality is defined in terms of program bytes only this lets you update metadata such as creation time. Note that
+     * you should be careful not to add scripts with a creation time of zero (the default!) because otherwise it will
+     * disable the important wallet checkpointing optimisation.
      *
      * @return how many scripts were added successfully
      */
@@ -822,7 +825,10 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
         keychainLock.lock();
         try {
             for (final Script script : scripts) {
-                if (watchedScripts.contains(script)) continue;
+                // Script.equals/hashCode() only takes into account the program bytes, so this step lets the user replace
+                // a script in the wallet with an incorrect creation time.
+                if (watchedScripts.contains(script))
+                    watchedScripts.remove(script);
                 if (script.getCreationTimeSeconds() == 0)
                     log.warn("Adding a script to the wallet with a creation time of zero, this will disable the checkpointing optimization!    {}", script);
                 watchedScripts.add(script);