Split the BlockChain.add method out into some smaller functions.

src/com/google/bitcoin/core/BlockChain.java

@@ -113,22 +113,9 @@ public class BlockChain {
             LOG(block.toString());
             throw e;
         }
-        // If this block is a full block, scan, otherwise it's just headers (eg from getheaders or a unit test).
+        // Inform the wallet about transactions relevant to our keys, then throw away the transaction data.
-        if (block.transactions != null) {
+        extractRelevantTransactions(block);
-            // Scan the transactions to find out if any sent money to us. We don't care about the rest.
+        assert block.transactions == null;
-            // TODO: We should also scan to see if any of our own keys sent money to somebody else and became spent.
-            for (Transaction tx : block.transactions) {
-                try {
-                    scanTransaction(tx);
-                } catch (ScriptException e) {
-                    // We don't want scripts we don't understand to break the block chain,
-                    // so just note that this tx was not scanned here and continue.
-                    LOG("Failed to parse a script: " + e.toString());
-                }
-            }
-        }
-        // We don't need the transaction data anymore. Free up some memory.
-        block.transactions = null;
 
         if (blockStore.get(block.getHash()) != null) {
             LOG("Already have block");
@@ -143,10 +130,19 @@ public class BlockChain {
             unconnectedBlocks.add(block);
             return false;
         } else {
-            // The block connects to somewhere on the chain. Not necessarily the top of the best known chain.
+            // It connects to somewhere on the chain. Not necessarily the top of the best known chain.
             checkDifficultyTransitions(storedPrev, block);
+            connectAndStoreBlock(block, storedPrev);
+        }
+
+        if (tryConnecting)
+            tryConnectingUnconnected();
+
+        return true;
+    }
+
+    private void connectAndStoreBlock(Block block, StoredBlock storedPrev) throws BlockStoreException, VerificationException {
         StoredBlock newStoredBlock = storedPrev.build(block);
-            // Store it.
         blockStore.put(newStoredBlock);
         if (storedPrev.equals(chainHead)) {
             // This block connects to the best known block, it is a normal continuation of the system.
@@ -166,10 +162,25 @@ public class BlockChain {
         }
     }
 
-        if (tryConnecting)
+    private void extractRelevantTransactions(Block block) throws VerificationException {
-            tryConnectingUnconnected();
+        // If this block is a full block, scan, otherwise it's just headers (eg from getheaders or a unit test).
-
+        if (block.transactions != null) {
-        return true;
+            // Scan the transactions to find out if any sent money to us. We don't care about the rest.
+            // TODO: We should also scan to see if any of our own keys sent money to somebody else and became spent.
+            for (Transaction tx : block.transactions) {
+                try {
+                    scanTransaction(tx);
+                } catch (ScriptException e) {
+                    // We don't want scripts we don't understand to break the block chain,
+                    // so just note that this tx was not scanned here and continue.
+                    LOG("Failed to parse a script: " + e.toString());
+                }
+            }
+        }
+        // Throw away the transactions. We have to do this because we can't hold all the transaction data for the
+        // production chain in memory at once. Because BitCoinJ implements client mode/simplified payment
+        // verification we don't store the transactions to disk or use them later anyway.
+        block.transactions = null;
     }
 
     private void setChainHead(StoredBlock chainHead) {