Replaced size() == / > 0 with isEmpty()

src/main/java/org/qortal/account/SelfSponsorshipAlgoV1.java

@@ -340,7 +340,7 @@ public class SelfSponsorshipAlgoV1 {
             return true;
         }
         transactionDataList.removeIf(t -> t.getTimestamp() >= this.snapshotTimestamp);
-        return transactionDataList.size() == 0;
+        return transactionDataList.isEmpty();
     }
 
     private static List<TransactionData> fetchTransactions(Repository repository, List<TransactionType> txTypes, String address, boolean reverse) throws DataException {

src/main/java/org/qortal/account/SelfSponsorshipAlgoV3.java

@@ -344,7 +344,7 @@ public class SelfSponsorshipAlgoV3 {
             return true;
         }
         transactionDataList.removeIf(t -> t.getTimestamp() <= this.snapshotTimestampV1 || t.getTimestamp() >= this.snapshotTimestampV3);
-        return transactionDataList.size() == 0;
+        return transactionDataList.isEmpty();
     }
 
     private static List<TransactionData> fetchTransactions(Repository repository, List<TransactionType> txTypes, String address, boolean reverse) throws DataException {

src/main/java/org/qortal/api/ApiRequest.java

@@ -141,7 +141,7 @@ public class ApiRequest {
 		}
 
 		String resultString = result.toString();
-		return resultString.length() > 0 ? resultString.substring(0, resultString.length() - 1) : resultString;
+		return !resultString.isEmpty() ? resultString.substring(0, resultString.length() - 1) : resultString;
 	}
 
 	/**

src/main/java/org/qortal/api/gateway/resource/GatewayResource.java

@@ -140,7 +140,7 @@ public class GatewayResource {
         }
 
         String prefix = StringUtils.join(prefixParts, "/");
-        if (prefix != null && prefix.length() > 0) {
+        if (prefix != null && !prefix.isEmpty()) {
             prefix = "/" + prefix;
         }
 

src/main/java/org/qortal/arbitrary/ArbitraryDataBuilder.java

@@ -104,7 +104,7 @@ public class ArbitraryDataBuilder {
         if (latestPut.getMethod() != Method.PUT) {
             throw new DataException("Expected PUT but received PATCH");
         }
-        if (transactionDataList.size() == 0) {
+        if (transactionDataList.isEmpty()) {
             throw new DataException(String.format("No transactions found for name %s, service %s, " +
                             "identifier: %s, since %d", name, service, this.identifierString(), latestPut.getTimestamp()));
         }
@@ -176,7 +176,7 @@ public class ArbitraryDataBuilder {
     }
 
     private void findLatestSignature() throws DataException {
-        if (this.transactions.size() == 0) {
+        if (this.transactions.isEmpty()) {
             throw new DataException("Unable to find latest signature from empty transaction list");
         }
 

src/main/java/org/qortal/arbitrary/ArbitraryDataFile.java

@@ -354,7 +354,7 @@ public class ArbitraryDataFile {
 
     public boolean join() {
         // Ensure we have chunks
-        if (this.chunks != null && this.chunks.size() > 0) {
+        if (this.chunks != null && !this.chunks.isEmpty()) {
 
             // Create temporary path for joined file
             // Use the user-specified temp dir, as it is deterministic, and is more likely to be located on reusable storage hardware
@@ -439,7 +439,7 @@ public class ArbitraryDataFile {
         boolean success = false;
 
         // Delete the individual chunks
-        if (this.chunks != null && this.chunks.size() > 0) {
+        if (this.chunks != null && !this.chunks.isEmpty()) {
             Iterator iterator = this.chunks.iterator();
             while (iterator.hasNext()) {
                 ArbitraryDataFileChunk chunk = (ArbitraryDataFileChunk) iterator.next();
@@ -709,7 +709,7 @@ public class ArbitraryDataFile {
     }
 
     public byte[] chunkHashes() throws DataException {
-        if (this.chunks != null && this.chunks.size() > 0) {
+        if (this.chunks != null && !this.chunks.isEmpty()) {
             // Return null if we only have one chunk, with the same hash as the parent
             if (Arrays.equals(this.digest(), this.chunks.get(0).digest())) {
                 return null;
@@ -736,7 +736,7 @@ public class ArbitraryDataFile {
     public List<byte[]> chunkHashList() {
         List<byte[]> chunks = new ArrayList<>();
 
-        if (this.chunks != null && this.chunks.size() > 0) {
+        if (this.chunks != null && !this.chunks.isEmpty()) {
             // Return null if we only have one chunk, with the same hash as the parent
             if (Arrays.equals(this.digest(), this.chunks.get(0).digest())) {
                 return null;
@@ -820,7 +820,7 @@ public class ArbitraryDataFile {
         String outputString = "";
         if (this.chunkCount() > 0) {
             for (ArbitraryDataFileChunk chunk : this.chunks) {
-                if (outputString.length() > 0) {
+                if (!outputString.isEmpty()) {
                     outputString = outputString.concat(",");
                 }
                 outputString = outputString.concat(chunk.digest58());

src/main/java/org/qortal/block/Block.java

@@ -1086,7 +1086,7 @@ public class Block {
 
 		// Online accounts should only be included in designated blocks; all others must be empty
 		if (!this.isOnlineAccountsBlock()) {
-			if (this.blockData.getOnlineAccountsCount() != 0 || accountIndexes.size() != 0) {
+			if (this.blockData.getOnlineAccountsCount() != 0 || !accountIndexes.isEmpty()) {
 				return ValidationResult.ONLINE_ACCOUNTS_INVALID;
 			}
 			// Not a designated online accounts block and account count is 0. Everything is correct so no need to validate further.

src/main/java/org/qortal/controller/Synchronizer.java

@@ -258,7 +258,7 @@ public class Synchronizer extends Thread {
 		peers.removeIf(Controller.hasNoRecentBlock);
 
 		final int peersRemoved = peersBeforeComparison - peers.size();
-		if (peersRemoved > 0 && peers.size() > 0)
+		if (peersRemoved > 0 && !peers.isEmpty())
 			LOGGER.debug(String.format("Ignoring %d peers on inferior chains. Peers remaining: %d", peersRemoved, peers.size()));
 
 		if (peers.isEmpty())
@@ -392,7 +392,7 @@ public class Synchronizer extends Thread {
 	private boolean checkRecoveryModeForPeers(List<Peer> qualifiedPeers) {
 		List<Peer> handshakedPeers = Network.getInstance().getImmutableHandshakedPeers();
 
-		if (handshakedPeers.size() > 0) {
+		if (!handshakedPeers.isEmpty()) {
 			// There is at least one handshaked peer
 			if (qualifiedPeers.isEmpty()) {
 				// There are no 'qualified' peers - i.e. peers that have a recent block we can sync to
@@ -445,7 +445,7 @@ public class Synchronizer extends Thread {
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			try {
 
-				if (peers.size() == 0)
+				if (peers.isEmpty())
 					return SynchronizationResult.NOTHING_TO_DO;
 
 				// If our latest block is very old, it's best that we don't try and determine the best peers to sync to.
@@ -701,7 +701,7 @@ public class Synchronizer extends Thread {
 
 						// Reduce minChainLength if needed. If we don't have any blocks, this peer will be excluded from chain weight comparisons later in the process, so we shouldn't update minChainLength
 						List <BlockSummaryData> peerBlockSummaries = peer.getCommonBlockData().getBlockSummariesAfterCommonBlock();
-						if (peerBlockSummaries != null && peerBlockSummaries.size() > 0)
+						if (peerBlockSummaries != null && !peerBlockSummaries.isEmpty())
 							if (peerBlockSummaries.size() < minChainLength)
 								minChainLength = peerBlockSummaries.size();
 					}
@@ -728,7 +728,7 @@ public class Synchronizer extends Thread {
 
 					// Calculate our chain weight
 					BigInteger ourChainWeight = BigInteger.valueOf(0);
-					if (ourBlockSummaries.size() > 0)
+					if (!ourBlockSummaries.isEmpty())
 						ourChainWeight = Block.calcChainWeight(commonBlockSummary.getHeight(), commonBlockSummary.getSignature(), ourBlockSummaries, maxHeightForChainWeightComparisons);
 
 					LOGGER.debug(String.format("Our chain weight based on %d blocks is %s", (usingSameLengthChainWeight ? minChainLength : ourBlockSummaries.size()), accurateFormatter.format(ourChainWeight)));
@@ -780,7 +780,7 @@ public class Synchronizer extends Thread {
 					}
 
 					// Now that we have selected the best peers, compare them against each other and remove any with lower weights
-					if (superiorPeersForComparison.size() > 0) {
+					if (!superiorPeersForComparison.isEmpty()) {
 						BigInteger bestChainWeight = null;
 						for (Peer peer : superiorPeersForComparison) {
 							// Increase bestChainWeight if needed
@@ -1290,7 +1290,7 @@ public class Synchronizer extends Thread {
 						cachedCommonBlockData.setBlockSummariesAfterCommonBlock(null);
 
                     // If we have already received newer blocks from this peer that what we have already, go ahead and apply them
-                    if (peerBlocks.size() > 0) {
+                    if (!peerBlocks.isEmpty()) {
 						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 						final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
 						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
@@ -1352,7 +1352,7 @@ public class Synchronizer extends Thread {
 
 				if (retryCount >= maxRetries) {
 					// If we have already received newer blocks from this peer that what we have already, go ahead and apply them
-					if (peerBlocks.size() > 0) {
+					if (!peerBlocks.isEmpty()) {
 						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
 						final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
 						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();

src/main/java/org/qortal/controller/arbitrary/ArbitraryDataFileListManager.java

@@ -605,7 +605,7 @@ public class ArbitraryDataFileListManager {
                         }
 
                         // Add the chunk hashes
-                        if (arbitraryDataFile.getChunkHashes().size() > 0) {
+                        if (!arbitraryDataFile.getChunkHashes().isEmpty()) {
                             requestedHashes.addAll(arbitraryDataFile.getChunkHashes());
                         }
                         // Add complete file if there are no hashes
@@ -641,7 +641,7 @@ public class ArbitraryDataFileListManager {
         }
 
         // We should only respond if we have at least one hash
-        if (hashes.size() > 0) {
+        if (!hashes.isEmpty()) {
 
             // Firstly we should keep track of the requesting peer, to allow for potential direct connections later
             ArbitraryDataFileManager.getInstance().addRecentDataRequest(requestingPeer);

src/main/java/org/qortal/controller/repository/NamesDatabaseIntegrityCheck.java

@@ -207,7 +207,7 @@ public class NamesDatabaseIntegrityCheck {
                         // FUTURE: check database integrity for names that have been updated and then the original name re-registered
                         else if (Objects.equals(updateNameTransactionData.getName(), registeredName)) {
                             String newName = updateNameTransactionData.getNewName();
-                            if (newName == null || newName.length() == 0) {
+                            if (newName == null || newName.isEmpty()) {
                                 // If new name is blank (or maybe null, just to be safe), it means that it stayed the same
                                 newName = registeredName;
                             }

src/main/java/org/qortal/crosschain/Bitcoiny.java

@@ -757,7 +757,7 @@ public abstract class Bitcoiny implements ForeignBlockchain {
 			Address address = Address.fromKey(this.params, keyChain.getKey(KeyChain.KeyPurpose.RECEIVE_FUNDS), ScriptType.P2PKH);
 
 			// if zero transactions, return address
-			if( 0 == getAddressTransactions(ScriptBuilder.createOutputScript(address).getProgram(), true).size() )
+			if(getAddressTransactions(ScriptBuilder.createOutputScript(address).getProgram(), true).isEmpty())
 				return address.toString();
 
 			// else try the next receive funds address

src/main/java/org/qortal/network/Network.java

@@ -810,7 +810,7 @@ public class Network {
                 .filter(peer -> peer.hasReachedMaxConnectionAge())
                 .collect(Collectors.toList());
 
-        if (peersToDisconnect != null && peersToDisconnect.size() > 0) {
+        if (peersToDisconnect != null && !peersToDisconnect.isEmpty()) {
             for (Peer peer : peersToDisconnect) {
                 LOGGER.debug("Forcing disconnection of peer {} because connection age ({} ms) " +
                         "has reached the maximum ({} ms)", peer, peer.getConnectionAge(), peer.getMaxConnectionAge());

src/main/java/org/qortal/network/Peer.java

@@ -859,7 +859,7 @@ public class Peer {
             }
         }
 
-        if (logStats && this.receivedMessageStats.size() > 0) {
+        if (logStats && !this.receivedMessageStats.isEmpty()) {
             StringBuilder statsBuilder = new StringBuilder(1024);
             statsBuilder.append("peer ").append(this).append(" message stats:\n=received=");
             appendMessageStats(statsBuilder, this.receivedMessageStats);

src/main/java/org/qortal/repository/hsqldb/HSQLDBArbitraryRepository.java

@@ -1024,7 +1024,7 @@ public class HSQLDBArbitraryRepository implements ArbitraryRepository {
 		String tag5 = null;
 
 		if (tags != null) {
-			if (tags.size() > 0) tag1 = tags.get(0);
+			if (!tags.isEmpty()) tag1 = tags.get(0);
 			if (tags.size() > 1) tag2 = tags.get(1);
 			if (tags.size() > 2) tag3 = tags.get(2);
 			if (tags.size() > 3) tag4 = tags.get(3);

src/main/java/org/qortal/transaction/ChatTransaction.java

@@ -168,7 +168,7 @@ public class ChatTransaction extends Transaction {
 
 		// Check for blocked author by registered name
 		List<NameData> names = this.repository.getNameRepository().getNamesByOwner(this.chatTransactionData.getSender());
-		if (names != null && names.size() > 0) {
+		if (names != null && !names.isEmpty()) {
 			for (NameData nameData : names) {
 				if (nameData != null && nameData.getName() != null) {
 					if (ListUtils.isNameBlocked(nameData.getName())) {

src/main/java/org/qortal/utils/Base58.java

@@ -111,7 +111,7 @@ public class Base58 {
         //
         // Nothing to do if we have an empty string
         //
-        if (string.length() == 0)
+        if (string.isEmpty())
             return null;
         //
         // Convert the input string to a byte sequence

src/main/java/org/qortal/utils/BlockArchiveUtils.java

@@ -59,7 +59,7 @@ public class BlockArchiveUtils {
         if (firstBlock == null || firstBlock.getBlockData().getHeight() != startHeight) {
             throw new IllegalStateException("Non matching first block when importing from archive");
         }
-        if (blockInfoList.size() > 0) {
+        if (!blockInfoList.isEmpty()) {
             BlockTransformation lastBlock = blockInfoList.get(blockInfoList.size() - 1);
             if (lastBlock == null || lastBlock.getBlockData().getHeight() != endHeight) {
                 throw new IllegalStateException("Non matching last block when importing from archive");

src/main/java/org/qortal/utils/Unicode.java

@@ -141,7 +141,7 @@ public abstract class Unicode {
 			while ((line = bufferedReader.readLine()) != null) {
 				line = line.trim();
 
-				if (line.startsWith("#") || line.length() == 0)
+				if (line.startsWith("#") || line.isEmpty())
 					continue;
 
 				String[] charCodes = line.split(",");