Various cleanup

src/main/java/com/sparrowwallet/drongo/KeyDerivation.java

@@ -61,7 +61,7 @@ public class KeyDerivation {
         String[] parsedNodes = path.replace("M", "").replace("m", "").split("/");
         for (String n : parsedNodes) {
             n = n.replaceAll(" ", "");
-            if (n.length() == 0) continue;
+            if (n.isEmpty()) continue;
             boolean isHard = n.endsWith("H") || n.endsWith("h") || n.endsWith("'");
             if (isHard) n = n.substring(0, n.length() - 1);
             if (n.equals("*")) n = Integer.toString(wildcardReplacement);

src/main/java/com/sparrowwallet/drongo/OutputDescriptor.java

@@ -434,12 +434,12 @@ public class OutputDescriptor {
                 if(extendedKey.getKey().hasPrivKey()) {
                     ExtendedKey privateExtendedKey = extendedKey;
                     List<ChildNumber> derivation = keyDerivation.getDerivation();
-                    int depth = derivation.size() == 0 ? scriptType.getDefaultDerivation().size() : derivation.size();
+                    int depth = derivation.isEmpty() ? scriptType.getDefaultDerivation().size() : derivation.size();
                     DeterministicKey prvKey = extendedKey.getKey();
                     DeterministicKey pubKey = new DeterministicKey(prvKey.getPath(), prvKey.getChainCode(), prvKey.getPubKey(), depth, extendedKey.getParentFingerprint());
                     extendedKey = new ExtendedKey(pubKey, pubKey.getParentFingerprint(), extendedKey.getKeyChildNumber());
 
-                    if(derivation.size() == 0) {
+                    if(derivation.isEmpty()) {
                         masterPrivateKeyMap.put(extendedKey, privateExtendedKey);
                     }
                 }

src/main/java/com/sparrowwallet/drongo/SecureString.java

@@ -10,7 +10,7 @@ import java.util.Arrays;
  * This is not a string but a CharSequence that can be cleared of its memory.
  * Important for handling passwords. Represents text that should be kept
  * confidential, such as by deleting it from computer memory when no longer
- * needed or garbaged collected.
+ * needed or garbage collected.
  */
 public class SecureString implements CharSequence {
 

src/main/java/com/sparrowwallet/drongo/Utils.java

@@ -160,22 +160,22 @@ public class Utils {
 
     /** Parse 4 bytes from the byte array (starting at the offset) as unsigned 32-bit integer in little endian format. */
     public static long readUint32(byte[] bytes, int offset) {
-        return (bytes[offset] & 0xffl) |
+        return (bytes[offset] & 0xffL) |
-                ((bytes[offset + 1] & 0xffl) << 8) |
+                ((bytes[offset + 1] & 0xffL) << 8) |
-                ((bytes[offset + 2] & 0xffl) << 16) |
+                ((bytes[offset + 2] & 0xffL) << 16) |
-                ((bytes[offset + 3] & 0xffl) << 24);
+                ((bytes[offset + 3] & 0xffL) << 24);
     }
 
     /** Parse 8 bytes from the byte array (starting at the offset) as signed 64-bit integer in little endian format. */
     public static long readInt64(byte[] bytes, int offset) {
-        return (bytes[offset] & 0xffl) |
+        return (bytes[offset] & 0xffL) |
-                ((bytes[offset + 1] & 0xffl) << 8) |
+                ((bytes[offset + 1] & 0xffL) << 8) |
-                ((bytes[offset + 2] & 0xffl) << 16) |
+                ((bytes[offset + 2] & 0xffL) << 16) |
-                ((bytes[offset + 3] & 0xffl) << 24) |
+                ((bytes[offset + 3] & 0xffL) << 24) |
-                ((bytes[offset + 4] & 0xffl) << 32) |
+                ((bytes[offset + 4] & 0xffL) << 32) |
-                ((bytes[offset + 5] & 0xffl) << 40) |
+                ((bytes[offset + 5] & 0xffL) << 40) |
-                ((bytes[offset + 6] & 0xffl) << 48) |
+                ((bytes[offset + 6] & 0xffL) << 48) |
-                ((bytes[offset + 7] & 0xffl) << 56);
+                ((bytes[offset + 7] & 0xffL) << 56);
     }
 
     /** Parse 2 bytes from the byte array (starting at the offset) as unsigned 16-bit integer in little endian format. */
@@ -197,10 +197,10 @@ public class Utils {
     /** Parse 4 bytes from the stream as unsigned 32-bit integer in little endian format. */
     public static long readUint32FromStream(InputStream is) {
         try {
-            return (is.read() & 0xffl) |
+            return (is.read() & 0xffL) |
-                    ((is.read() & 0xffl) << 8) |
+                    ((is.read() & 0xffL) << 8) |
-                    ((is.read() & 0xffl) << 16) |
+                    ((is.read() & 0xffL) << 16) |
-                    ((is.read() & 0xffl) << 24);
+                    ((is.read() & 0xffL) << 24);
         } catch (IOException x) {
             throw new RuntimeException(x);
         }

src/main/java/com/sparrowwallet/drongo/WatchWallet.java

@@ -9,10 +9,10 @@ import java.util.List;
 public class WatchWallet {
     private static final int LOOK_AHEAD_LIMIT = 500;
 
-    private String name;
+    private final String name;
-    private OutputDescriptor outputDescriptor;
+    private final OutputDescriptor outputDescriptor;
 
-    private HashMap<Address,List<ChildNumber>> addresses = new HashMap<>(LOOK_AHEAD_LIMIT*2);
+    private final HashMap<Address, List<ChildNumber>> addresses = new HashMap<>(LOOK_AHEAD_LIMIT*2);
 
     public WatchWallet(String name, String descriptor) {
         this.name = name;

src/main/java/com/sparrowwallet/drongo/crypto/DeterministicHierarchy.java

@@ -34,7 +34,7 @@ public class DeterministicHierarchy {
      */
     public DeterministicKey get(List<ChildNumber> path) throws HDDerivationException {
         if(!keys.containsKey(path)) {
-            if(path.size() == 0) {
+            if(path.isEmpty()) {
                 throw new IllegalArgumentException("Can't derive the master key: nothing to derive from.");
             }
 

src/main/java/com/sparrowwallet/drongo/crypto/DeterministicKey.java

@@ -160,7 +160,7 @@ public class DeterministicKey extends ECKey {
 
     /** Returns the last element of the path returned by {@link DeterministicKey#getPath()} */
     public ChildNumber getChildNumber() {
-        return childNumberPath.size() == 0 ? ChildNumber.ZERO : childNumberPath.get(childNumberPath.size() - 1);
+        return childNumberPath.isEmpty() ? ChildNumber.ZERO : childNumberPath.get(childNumberPath.size() - 1);
     }
 
     public byte[] getChainCode() {

src/main/java/com/sparrowwallet/drongo/crypto/ECKey.java

@@ -625,7 +625,7 @@ public class ECKey {
      * format generated by signmessage/verifymessage RPCs and GUI menu options. They are intended for humans to verify
      * their communications with each other, hence the base64 format and the fact that the input is text.
      *
-     * @param message         Some piece of human readable text.
+     * @param message         Some piece of human-readable text.
      * @param signatureBase64 The Bitcoin-format message signature in base64
      * @param electrumFormat  Whether to generate a key following Electrum's approach of regarding P2SH-P2WSH as the same as P2PKH uncompressed
      * @throws SignatureException If the public key could not be recovered or if there was a signature format error.

src/main/java/com/sparrowwallet/drongo/protocol/Base58.java

@@ -132,7 +132,7 @@ public class Base58 {
      * @return the decoded data bytes
      */
     public static byte[] decode(String input) {
-        if (input.length() == 0) {
+        if (input.isEmpty()) {
             return new byte[0];
         }
         // Convert the base58-encoded ASCII chars to a base58 byte sequence (base58 digits).

src/main/java/com/sparrowwallet/drongo/protocol/Bech32.java

@@ -126,7 +126,7 @@ public class Bech32 {
 
         /** Encode a Bech32 string. */
     public static String encode(String hrp, Encoding encoding, final byte[] values) {
-        if(hrp.length() < 1) {
+        if(hrp.isEmpty()) {
             throw new ProtocolException("Human-readable part is too short");
         }
 

src/main/java/com/sparrowwallet/drongo/protocol/Transaction.java

@@ -393,7 +393,7 @@ public class Transaction extends ChildMessage {
     }
 
     public void verify() throws VerificationException {
-        if (inputs.size() == 0 || outputs.size() == 0)
+        if (inputs.isEmpty() || outputs.isEmpty())
             throw new VerificationException.EmptyInputsOrOutputs();
         if (this.getMessageSize() > MAX_BLOCK_SIZE)
             throw new VerificationException.LargerThanMaxBlockSize();
@@ -464,7 +464,7 @@ public class Transaction extends ChildMessage {
 
             // This step has no purpose beyond being synchronized with Bitcoin Core's bugs. OP_CODESEPARATOR
             // is a legacy holdover from a previous, broken design of executing scripts that shipped in Bitcoin 0.1.
-            // It was seriously flawed and would have let anyone take anyone elses money. Later versions switched to
+            // It was seriously flawed and would have let anyone take anyone else's money. Later versions switched to
             // the design we use today where scripts are executed independently but share a stack. This left the
             // OP_CODESEPARATOR instruction having no purpose as it was only meant to be used internally, not actually
             // ever put into scripts. Deleting OP_CODESEPARATOR is a step that should never be required but if we don't

src/main/java/com/sparrowwallet/drongo/wallet/Bip39MnemonicCode.java

@@ -121,7 +121,7 @@ public class Bip39MnemonicCode {
             throw new MnemonicException.MnemonicLengthException("Word list size must be multiple of three words.");
         }
 
-        if (words.size() == 0) {
+        if (words.isEmpty()) {
             throw new MnemonicException.MnemonicLengthException("Word list is empty.");
         }
 

src/main/java/com/sparrowwallet/drongo/wallet/PresetUtxoSelector.java

@@ -29,7 +29,7 @@ public class PresetUtxoSelector extends SingleSetUtxoSelector {
 
     @Override
     public Collection<BlockTransactionHashIndex> select(long targetValue, Collection<OutputGroup> candidates) {
-        List<BlockTransactionHashIndex> flattenedCandidates = candidates.stream().flatMap(outputGroup -> outputGroup.getUtxos().stream()).collect(Collectors.toList());
+        List<BlockTransactionHashIndex> flattenedCandidates = candidates.stream().flatMap(outputGroup -> outputGroup.getUtxos().stream()).toList();
         List<BlockTransactionHashIndex> utxos = new ArrayList<>();
 
         //Don't use equals() here as we don't want to consider height which may change as txes are confirmed

src/main/java/com/sparrowwallet/drongo/wallet/SeedQR.java

@@ -20,7 +20,7 @@ public class SeedQR {
         List<Integer> indexes = IntStream.iterate(0, i -> i + 4).limit((int)Math.ceil(seedQr.length() / 4.0))
                 .mapToObj(i -> seedQr.substring(i, Math.min(i + 4, seedQr.length())))
                 .map(Integer::parseInt)
-                .collect(Collectors.toList());
+                .toList();
 
         List<String> words = new ArrayList<>(indexes.size());
         for(Integer index : indexes) {

src/test/java/com/sparrowwallet/drongo/wallet/WalletTest.java

@@ -17,9 +17,13 @@ import org.junit.jupiter.api.Test;
 import java.util.List;
 
 public class WalletTest {
+    private static final String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
+
+    private static final String words2 = "chef huge whisper year move obscure post pepper play minute foster lawn";
+
+
     @Test
     public void encryptTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
         Wallet wallet = new Wallet();
         wallet.setPolicyType(PolicyType.SINGLE);
@@ -107,7 +111,6 @@ public class WalletTest {
 
     @Test
     public void p2pkhDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
         Wallet wallet = new Wallet();
         wallet.setPolicyType(PolicyType.SINGLE);
@@ -124,7 +127,6 @@ public class WalletTest {
 
     @Test
     public void p2shP2wpkhDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
         Wallet wallet = new Wallet();
         wallet.setPolicyType(PolicyType.SINGLE);
@@ -141,7 +143,6 @@ public class WalletTest {
 
     @Test
     public void p2wpkhDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
         Wallet wallet = new Wallet();
         wallet.setPolicyType(PolicyType.SINGLE);
@@ -158,10 +159,8 @@ public class WalletTest {
 
     @Test
     public void p2shDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
 
-        String words2 = "chef huge whisper year move obscure post pepper play minute foster lawn";
         DeterministicSeed seed2 = new DeterministicSeed(words2, "", 0, DeterministicSeed.Type.BIP39);
 
         Wallet wallet = new Wallet();
@@ -185,10 +184,8 @@ public class WalletTest {
 
     @Test
     public void p2shP2wshDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
 
-        String words2 = "chef huge whisper year move obscure post pepper play minute foster lawn";
         DeterministicSeed seed2 = new DeterministicSeed(words2, "", 0, DeterministicSeed.Type.BIP39);
 
         Wallet wallet = new Wallet();
@@ -212,10 +209,8 @@ public class WalletTest {
 
     @Test
     public void p2wshDerivationTest() throws MnemonicException {
-        String words = "absent essay fox snake vast pumpkin height crouch silent bulb excuse razor";
         DeterministicSeed seed = new DeterministicSeed(words, "pp", 0, DeterministicSeed.Type.BIP39);
 
-        String words2 = "chef huge whisper year move obscure post pepper play minute foster lawn";
         DeterministicSeed seed2 = new DeterministicSeed(words2, "", 0, DeterministicSeed.Type.BIP39);
 
         Wallet wallet = new Wallet();