Coin.toFriendlyFormat() includes denomination (BTC). This saves a lot of string concatenation code.

core/src/main/java/com/google/bitcoin/core/Coin.java

@@ -206,7 +206,7 @@ public final class Coin implements Comparable<Coin>, Serializable {
         return this.value;
     }
 
-    private static final CoinFormat FRIENDLY_FORMAT = CoinFormat.BTC.minDecimals(2).repeatOptionalDecimals(1, 6).noCode();
+    private static final CoinFormat FRIENDLY_FORMAT = CoinFormat.BTC.minDecimals(2).repeatOptionalDecimals(1, 6).postfixCode();
 
     /**
      * Returns the value as a 0.12 type string. More digits after the decimal place will be used

core/src/main/java/com/google/bitcoin/core/Transaction.java

@@ -655,7 +655,7 @@ public class Transaction extends ChildMessage implements Serializable {
                 Script scriptSig = in.getScriptSig();
                 s.append(scriptSig);
                 if (in.getValue() != null)
-                    s.append(" ").append(in.getValue().toFriendlyString()).append(" BTC");
+                    s.append(" ").append(in.getValue().toFriendlyString());
                 s.append("\n          ");
                 s.append("outpoint:");
                 final TransactionOutPoint outpoint = in.getOutpoint();
@@ -678,7 +678,6 @@ public class Transaction extends ChildMessage implements Serializable {
                 s.append(scriptPubKey);
                 s.append(" ");
                 s.append(out.getValue().toFriendlyString());
-                s.append(" BTC");
                 if (!out.isAvailableForSpending()) {
                     s.append(" Spent");
                 }

core/src/main/java/com/google/bitcoin/core/Wallet.java

@@ -1210,8 +1210,8 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
             Coin valueSentToMe = tx.getValueSentToMe(this);
             Coin valueSentFromMe = tx.getValueSentFromMe(this);
             if (log.isInfoEnabled()) {
-                log.info(String.format("Received a pending transaction %s that spends %s BTC from our own wallet," +
+                log.info(String.format("Received a pending transaction %s that spends %s from our own wallet," +
-                        " and sends us %s BTC", tx.getHashAsString(), valueSentFromMe.toFriendlyString(),
+                        " and sends us %s", tx.getHashAsString(), valueSentFromMe.toFriendlyString(),
                         valueSentToMe.toFriendlyString()));
             }
             if (tx.getConfidence().getSource().equals(TransactionConfidence.Source.UNKNOWN)) {
@@ -1390,7 +1390,7 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
         Coin valueSentToMe = tx.getValueSentToMe(this);
         Coin valueDifference = valueSentToMe.subtract(valueSentFromMe);
 
-        log.info("Received tx{} for {} BTC: {} [{}] in block {}", sideChain ? " on a side chain" : "",
+        log.info("Received tx{} for {}: {} [{}] in block {}", sideChain ? " on a side chain" : "",
                 valueDifference.toFriendlyString(), tx.getHashAsString(), relativityOffset,
                 block != null ? block.getHeader().getHash() : "(unit test)");
 
@@ -2495,7 +2495,7 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
                 value = value.add(output.getValue());
             }
 
-            log.info("Completing send tx with {} outputs totalling {} BTC (not including fees)",
+            log.info("Completing send tx with {} outputs totalling {} (not including fees)",
                     req.tx.getOutputs().size(), value.toFriendlyString());
 
             // If any inputs have already been added, we don't need to get their value from wallet
@@ -2544,7 +2544,7 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
                 bestCoinSelection = selector.select(NetworkParameters.MAX_MONEY, candidates);
                 candidates = null;  // Selector took ownership and might have changed candidates. Don't access again.
                 req.tx.getOutput(0).setValue(bestCoinSelection.valueGathered);
-                log.info("  emptying {} BTC", bestCoinSelection.valueGathered.toFriendlyString());
+                log.info("  emptying {}", bestCoinSelection.valueGathered.toFriendlyString());
             }
 
             for (TransactionOutput output : bestCoinSelection.gathered)
@@ -2560,7 +2560,7 @@ public class Wallet extends BaseTaggableObject implements Serializable, BlockCha
 
             if (bestChangeOutput != null) {
                 req.tx.addOutput(bestChangeOutput);
-                log.info("  with {} BTC change", bestChangeOutput.getValue().toFriendlyString());
+                log.info("  with {} change", bestChangeOutput.getValue().toFriendlyString());
             }
 
             // Now shuffle the outputs to obfuscate which is the change.

core/src/test/java/com/google/bitcoin/core/ChainSplitTest.java

@@ -94,7 +94,7 @@ public class ChainSplitTest {
         assertFalse(reorgHappened.get());
         assertEquals(2, walletChanged.get());
         // We got two blocks which sent 50 coins each to us.
-        assertEquals("100.00", wallet.getBalance().toFriendlyString());
+        assertEquals(Coin.valueOf(100, 0), wallet.getBalance());
         // We now have the following chain:
         //     genesis -> b1 -> b2
         //
@@ -109,7 +109,7 @@ public class ChainSplitTest {
         Threading.waitForUserCode();
         assertFalse(reorgHappened.get());  // No re-org took place.
         assertEquals(2, walletChanged.get());
-        assertEquals("100.00", wallet.getBalance().toFriendlyString());
+        assertEquals(Coin.valueOf(100, 0), wallet.getBalance());
         // Check we can handle multi-way splits: this is almost certainly going to be extremely rare, but we have to
         // handle it anyway. The same transaction appears in b7/b8 (side chain) but not b2 or b3.
         //     genesis -> b1--> b2
@@ -128,7 +128,7 @@ public class ChainSplitTest {
         assertEquals(2, wallet.getTransaction(tHash).getAppearsInHashes().size());
         assertFalse(reorgHappened.get());  // No re-org took place.
         assertEquals(5, walletChanged.get());
-        assertEquals("100.00", wallet.getBalance().toFriendlyString());
+        assertEquals(Coin.valueOf(100, 0), wallet.getBalance());
         // Now we add another block to make the alternative chain longer.
         assertTrue(chain.add(b3.createNextBlock(someOtherGuy)));
         Threading.waitForUserCode();
@@ -153,7 +153,7 @@ public class ChainSplitTest {
         Threading.waitForUserCode();
         assertTrue(reorgHappened.get());
         assertEquals(9, walletChanged.get());
-        assertEquals("200.00", wallet.getBalance().toFriendlyString());
+        assertEquals(Coin.valueOf(200, 0), wallet.getBalance());
     }
 
     @Test
@@ -520,7 +520,7 @@ public class ChainSplitTest {
         BigInteger newWork3 = work3.add(work7).add(work8);
         assertEquals(newWork3, txns.get(2).getConfidence().getWorkDone());
 
-        assertEquals("250.00", wallet.getBalance().toFriendlyString());
+        assertEquals(Coin.valueOf(250, 0), wallet.getBalance());
 
         // Now add two more blocks that don't send coins to us. Despite being irrelevant the wallet should still update.
         Block b9 = b8.createNextBlock(someOtherGuy);

core/src/test/java/com/google/bitcoin/core/CoinTest.java

@@ -94,10 +94,10 @@ public class CoinTest {
 
     @Test
     public void testToFriendlyString() {
-        assertEquals("1.00", COIN.toFriendlyString());
+        assertEquals("1.00 BTC", COIN.toFriendlyString());
-        assertEquals("1.23", valueOf(1, 23).toFriendlyString());
+        assertEquals("1.23 BTC", valueOf(1, 23).toFriendlyString());
-        assertEquals("0.001", COIN.divide(1000).toFriendlyString());
+        assertEquals("0.001 BTC", COIN.divide(1000).toFriendlyString());
-        assertEquals("-1.23", valueOf(1, 23).negate().toFriendlyString());
+        assertEquals("-1.23 BTC", valueOf(1, 23).negate().toFriendlyString());
     }
 
     /**

core/src/test/java/com/google/bitcoin/core/WalletTest.java

@@ -533,18 +533,18 @@ public class WalletTest extends TestWithWallet {
         confTxns.clear();
         sendMoneyToWallet(send1, AbstractBlockChain.NewBlockType.BEST_CHAIN);
         Threading.waitForUserCode();
-        assertEquals(wallet.getBalance().toFriendlyString(), "0.90");
+        assertEquals(Coin.valueOf(0, 90), wallet.getBalance());
         assertEquals(null, txn[0]);
         assertEquals(2, confTxns.size());
         assertEquals(txn[1].getHash(), send1.getHash());
-        assertEquals(bigints[2].toFriendlyString(), "1.00");
+        assertEquals(Coin.COIN, bigints[2]);
-        assertEquals(bigints[3].toFriendlyString(), "0.90");
+        assertEquals(Coin.valueOf(0, 90), bigints[3]);
         // And we do it again after the catchup.
         Transaction send2 = wallet.createSend(new ECKey().toAddress(params), valueOf(0, 10));
         // What we'd really like to do is prove the official client would accept it .... no such luck unfortunately.
         wallet.commitTx(send2);
         sendMoneyToWallet(send2, AbstractBlockChain.NewBlockType.BEST_CHAIN);
-        assertEquals(wallet.getBalance().toFriendlyString(), "0.80");
+        assertEquals(Coin.valueOf(0, 80), wallet.getBalance());
         Threading.waitForUserCode();
         BlockPair b4 = createFakeBlock(blockStore);
         confTxns.clear();

examples/src/main/java/com/google/bitcoin/examples/ExamplePaymentChannelClient.java

@@ -169,7 +169,7 @@ public class ExamplePaymentChannelClient {
         ListenableFuture<Coin> balanceFuture = appKit.wallet().getBalanceFuture(amountPlusFee, Wallet.BalanceType.ESTIMATED);
         if (!balanceFuture.isDone()) {
             System.out.println("Please send " + amountPlusFee.toFriendlyString() +
-                    " BTC to " + myKey.toAddress(params));
+                    " to " + myKey.toAddress(params));
             Futures.getUnchecked(balanceFuture);
         }
     }

examples/src/main/java/com/google/bitcoin/examples/ForwardingService.java

@@ -121,7 +121,7 @@ public class ForwardingService {
     private static void forwardCoins(Transaction tx) {
         try {
             Coin value = tx.getValueSentToMe(kit.wallet());
-            System.out.println("Forwarding " + value.toFriendlyString() + " BTC");
+            System.out.println("Forwarding " + value.toFriendlyString());
             // Now send the coins back! Send with a small fee attached to ensure rapid confirmation.
             final Coin amountToSend = value.subtract(Transaction.REFERENCE_DEFAULT_MIN_TX_FEE);
             final Wallet.SendResult sendResult = kit.wallet().sendCoins(kit.peerGroup(), forwardingAddress, amountToSend);

examples/src/main/java/com/google/bitcoin/examples/PrivateKeys.java

@@ -68,7 +68,7 @@ public class PrivateKeys {
             peerGroup.stopAsync();
 
             // And take them!
-            System.out.println("Claiming " + wallet.getBalance().toFriendlyString() + " coins");
+            System.out.println("Claiming " + wallet.getBalance().toFriendlyString());
             wallet.sendCoins(peerGroup, destination, wallet.getBalance());
             // Wait a few seconds to let the packets flush out to the network (ugly).
             Thread.sleep(5000);

tools/src/main/java/com/google/bitcoin/tools/WalletTool.java

@@ -616,7 +616,7 @@ public class WalletTool {
     private static void send(PaymentSession session) {
         try {
             System.out.println("Payment Request");
-            System.out.println("Coin: " + session.getValue().toFriendlyString() + " BTC");
+            System.out.println("Coin: " + session.getValue().toFriendlyString());
             System.out.println("Date: " + session.getDate());
             System.out.println("Memo: " + session.getMemo());
             if (session.pkiVerificationData != null) {