Use String.isEmpty() in some places

h2/src/main/org/h2/command/ddl/CreateUser.java

@@ -74,7 +74,7 @@ public class CreateUser extends DefineCommand {
         char[] passwordChars = pwd == null ? new char[0] : pwd.toCharArray();
         byte[] userPasswordHash;
         String userName = user.getName();
-        if (userName.length() == 0 && passwordChars.length == 0) {
+        if (userName.isEmpty() && passwordChars.length == 0) {
             userPasswordHash = new byte[0];
         } else {
             userPasswordHash = SHA256.getKeyPasswordHash(userName, passwordChars);

h2/src/main/org/h2/engine/ConnectionInfo.java

@@ -252,7 +252,7 @@ public class ConnectionInfo implements Cloneable {
             url = url.substring(0, idx);
             String[] list = StringUtils.arraySplit(settings, ';', false);
             for (String setting : list) {
-                if (setting.length() == 0) {
+                if (setting.isEmpty()) {
                     continue;
                 }
                 int equal = setting.indexOf('=');
@@ -326,7 +326,7 @@ public class ConnectionInfo implements Cloneable {
         if (passwordHash) {
             return StringUtils.convertHexToBytes(new String(password));
         }
-        if (userName.length() == 0 && password.length == 0) {
+        if (userName.isEmpty() && password.length == 0) {
             return new byte[0];
         }
         return SHA256.getKeyPasswordHash(userName, password);
@@ -643,7 +643,7 @@ public class ConnectionInfo implements Cloneable {
 
     private static String remapURL(String url) {
         String urlMap = SysProperties.URL_MAP;
-        if (urlMap != null && urlMap.length() > 0) {
+        if (urlMap != null && !urlMap.isEmpty()) {
             try {
                 SortedProperties prop;
                 prop = SortedProperties.loadProperties(urlMap);
@@ -653,7 +653,7 @@ public class ConnectionInfo implements Cloneable {
                     prop.store(urlMap);
                 } else {
                     url2 = url2.trim();
-                    if (url2.length() > 0) {
+                    if (!url2.isEmpty()) {
                         return url2;
                     }
                 }

h2/src/main/org/h2/engine/Database.java

@@ -642,7 +642,7 @@ public class Database implements DataHandler {
                 n = tokenizer.nextToken();
             }
         }
-        if (n == null || n.length() == 0) {
+        if (n == null || n.isEmpty()) {
             n = "unnamed";
         }
         return dbSettings.databaseToUpper ? StringUtils.toUpperEnglish(n) : n;
@@ -2274,7 +2274,7 @@ public class Database implements DataHandler {
     }
 
     public void setEventListenerClass(String className) {
-        if (className == null || className.length() == 0) {
+        if (className == null || className.isEmpty()) {
             eventListener = null;
         } else {
             try {

h2/src/main/org/h2/expression/CompareLike.java

@@ -72,7 +72,7 @@ public class CompareLike extends Condition {
     }
 
     private static Character getEscapeChar(String s) {
-        return s == null || s.length() == 0 ? null : s.charAt(0);
+        return s == null || s.isEmpty() ? null : s.charAt(0);
     }
 
     @Override

h2/src/main/org/h2/expression/Function.java

@@ -681,7 +681,7 @@ public class Function extends Expression implements FunctionCall {
             // string
         case ASCII: {
             String s = v0.getString();
-            if (s.length() == 0) {
+            if (s.isEmpty()) {
                 result = ValueNull.INSTANCE;
             } else {
                 result = ValueInt.get(s.charAt(0));
@@ -2710,19 +2710,17 @@ public class Function extends Expression implements FunctionCall {
             String fieldDelimiter, String escapeCharacter) {
         if (fieldSeparator != null) {
             csv.setFieldSeparatorWrite(fieldSeparator);
-            if (fieldSeparator.length() > 0) {
+            if (!fieldSeparator.isEmpty()) {
                 char fs = fieldSeparator.charAt(0);
                 csv.setFieldSeparatorRead(fs);
             }
         }
         if (fieldDelimiter != null) {
-            char fd = fieldDelimiter.length() == 0 ?
-                    0 : fieldDelimiter.charAt(0);
+            char fd = fieldDelimiter.isEmpty() ? 0 : fieldDelimiter.charAt(0);
             csv.setFieldDelimiter(fd);
         }
         if (escapeCharacter != null) {
-            char ec = escapeCharacter.length() == 0 ?
-                    0 : escapeCharacter.charAt(0);
+            char ec = escapeCharacter.isEmpty() ? 0 : escapeCharacter.charAt(0);
             csv.setEscapeCharacter(ec);
         }
     }

h2/src/main/org/h2/jdbc/JdbcDatabaseMetaData.java

@@ -3093,14 +3093,14 @@ public class JdbcDatabaseMetaData extends TraceObject implements
     }
 
     private static String getSchemaPattern(String pattern) {
-        return pattern == null ? "%" : pattern.length() == 0 ?
+        return pattern == null ? "%" : pattern.isEmpty() ?
                 Constants.SCHEMA_MAIN : pattern;
     }
 
     private static String getCatalogPattern(String catalogPattern) {
         // Workaround for OpenOffice: getColumns is called with "" as the
         // catalog
-        return catalogPattern == null || catalogPattern.length() == 0 ?
+        return catalogPattern == null || catalogPattern.isEmpty() ?
                 "%" : catalogPattern;
     }
 

h2/src/main/org/h2/server/pg/PgServerThread.java

@@ -180,7 +180,7 @@ public class PgServerThread implements Runnable {
                         " (" + (version >> 16) + "." + (version & 0xff) + ")");
                 while (true) {
                     String param = readString();
-                    if (param.length() == 0) {
+                    if (param.isEmpty()) {
                         break;
                     }
                     String value = readString();

h2/src/main/org/h2/server/web/PageParser.java

@@ -240,14 +240,15 @@ public class PageParser {
         if (s == null) {
             return null;
         }
+        int length = s.length();
         if (convertBreakAndSpace) {
-            if (s.length() == 0) {
+            if (length == 0) {
                 return " ";
             }
         }
-        StringBuilder buff = new StringBuilder(s.length());
+        StringBuilder buff = new StringBuilder(length);
         boolean convertSpace = true;
-        for (int i = 0; i < s.length(); i++) {
+        for (int i = 0; i < length; i++) {
             char c = s.charAt(i);
             if (c == ' ' || c == '\t') {
                 // convert tabs into spaces
@@ -312,11 +313,12 @@ public class PageParser {
         if (s == null) {
             return null;
         }
-        if (s.length() == 0) {
+        int length = s.length();
+        if (length == 0) {
             return "";
         }
-        StringBuilder buff = new StringBuilder(s.length());
-        for (int i = 0; i < s.length(); i++) {
+        StringBuilder buff = new StringBuilder(length);
+        for (int i = 0; i < length; i++) {
             char c = s.charAt(i);
             switch (c) {
             case '"':

h2/src/main/org/h2/server/web/WebSession.java

@@ -167,7 +167,7 @@ class WebSession {
             return;
         }
         sql = sql.trim();
-        if (sql.length() == 0) {
+        if (sql.isEmpty()) {
             return;
         }
         if (commandHistory.size() > MAX_HISTORY) {

h2/src/main/org/h2/store/fs/FilePathZip.java

@@ -51,7 +51,7 @@ public class FilePathZip extends FilePath {
     public boolean exists() {
         try {
             String entryName = getEntryName();
-            if (entryName.length() == 0) {
+            if (entryName.isEmpty()) {
                 return true;
             }
             try (ZipFile file = openZipFile()) {
@@ -88,7 +88,7 @@ public class FilePathZip extends FilePath {
     public boolean isDirectory() {
         try {
             String entryName = getEntryName();
-            if (entryName.length() == 0) {
+            if (entryName.isEmpty()) {
                 return true;
             }
             try (ZipFile file = openZipFile()) {

h2/src/main/org/h2/tools/Backup.java

@@ -108,7 +108,7 @@ public class Backup extends Tool {
     private void process(String zipFileName, String directory, String db,
             boolean quiet) throws SQLException {
         List<String> list;
-        boolean allFiles = db != null && db.length() == 0;
+        boolean allFiles = db != null && db.isEmpty();
         if (allFiles) {
             list = FileUtils.newDirectoryStream(directory);
         } else {

h2/src/main/org/h2/tools/Csv.java

@@ -228,7 +228,7 @@ public class Csv implements SimpleRowSource {
         for (int i = 0; i < columnNames.length; i++) {
             StringBuilder buff = new StringBuilder();
             String n = columnNames[i];
-            if (n == null || n.length() == 0) {
+            if (n == null || n.isEmpty()) {
                 buff.append('C').append(i + 1);
             } else {
                 buff.append(n);
@@ -350,7 +350,7 @@ public class Csv implements SimpleRowSource {
                     list.add(v);
                 }
             } else {
-                if (v.length() == 0) {
+                if (v.isEmpty()) {
                     v = "COLUMN" + list.size();
                 } else if (!caseSensitiveColumnNames && isSimpleColumnName(v)) {
                     v = StringUtils.toUpperEnglish(v);
@@ -827,13 +827,13 @@ public class Csv implements SimpleRowSource {
         String charset = null;
         String[] keyValuePairs = StringUtils.arraySplit(options, ' ', false);
         for (String pair : keyValuePairs) {
-            if (pair.length() == 0) {
+            if (pair.isEmpty()) {
                 continue;
             }
             int index = pair.indexOf('=');
             String key = StringUtils.trim(pair.substring(0, index), true, true, " ");
             String value = pair.substring(index + 1);
-            char ch = value.length() == 0 ? 0 : value.charAt(0);
+            char ch = value.isEmpty() ? 0 : value.charAt(0);
             if (isParam(key, "escape", "esc", "escapeCharacter")) {
                 setEscapeCharacter(ch);
             } else if (isParam(key, "fieldDelimiter", "fieldDelim")) {

h2/src/main/org/h2/tools/RunScript.java

@@ -205,7 +205,7 @@ public class RunScript extends Tool {
                 break;
             }
             String trim = sql.trim();
-            if (trim.length() == 0) {
+            if (trim.isEmpty()) {
                 continue;
             }
             if (trim.startsWith("@") && StringUtils.toUpperEnglish(trim).

h2/src/main/org/h2/tools/Shell.java

@@ -220,7 +220,7 @@ public class Shell extends Tool implements Runnable {
                     break;
                 }
                 String trimmed = line.trim();
-                if (trimmed.length() == 0) {
+                if (trimmed.isEmpty()) {
                     continue;
                 }
                 boolean end = trimmed.endsWith(";");
@@ -366,7 +366,7 @@ public class Shell extends Tool implements Runnable {
         println("[Enter]   Hide");
         print("Password  ");
         String password = readLine();
-        if (password.length() == 0) {
+        if (password.isEmpty()) {
             password = readPassword();
         }
         conn = JdbcUtils.getConnection(driver, url, user, password);
@@ -433,7 +433,7 @@ public class Shell extends Tool implements Runnable {
 
     private String readLine(String defaultValue) throws IOException {
         String s = readLine();
-        return s.length() == 0 ? defaultValue : s;
+        return s.isEmpty() ? defaultValue : s;
     }
 
     private String readLine() throws IOException {

h2/src/main/org/h2/util/NetUtils.java

@@ -155,7 +155,7 @@ public class NetUtils {
      */
     private static InetAddress getBindAddress() throws UnknownHostException {
         String host = SysProperties.BIND_ADDRESS;
-        if (host == null || host.length() == 0) {
+        if (host == null || host.isEmpty()) {
             return null;
         }
         synchronized (NetUtils.class) {

h2/src/main/org/h2/util/ParserUtil.java

@@ -238,10 +238,11 @@ public class ParserUtil {
      * @return true if it is a keyword
      */
     public static boolean isKeyword(String s) {
-        if (s.length() == 0) {
+        int length = s.length();
+        if (length == 0) {
             return false;
         }
-        return getSaveTokenType(s, false, 0, s.length(), false) != IDENTIFIER;
+        return getSaveTokenType(s, false, 0, length, false) != IDENTIFIER;
     }
 
     /**
@@ -252,7 +253,8 @@ public class ParserUtil {
      * @throws NullPointerException if s is {@code null}
      */
     public static boolean isSimpleIdentifier(String s) {
-        if (s.length() == 0) {
+        int length = s.length();
+        if (length == 0) {
             return false;
         }
         char c = s.charAt(0);
@@ -260,13 +262,13 @@ public class ParserUtil {
         if ((UPPER_OR_OTHER_LETTER >>> Character.getType(c) & 1) == 0 && c != '_') {
             return false;
         }
-        for (int i = 1, length = s.length(); i < length; i++) {
+        for (int i = 1; i < length; i++) {
             c = s.charAt(i);
             if ((UPPER_OR_OTHER_LETTER_OR_DIGIT >>> Character.getType(c) & 1) == 0 && c != '_') {
                 return false;
             }
         }
-        return getSaveTokenType(s, false, 0, s.length(), true) == IDENTIFIER;
+        return getSaveTokenType(s, false, 0, length, true) == IDENTIFIER;
     }
 
     /**

h2/src/main/org/h2/util/StringUtils.java

@@ -777,7 +777,7 @@ public class StringUtils {
      * @return true if it is null or empty
      */
     public static boolean isNullOrEmpty(String s) {
-        return s == null || s.length() == 0;
+        return s == null || s.isEmpty();
     }
 
     /**
@@ -810,7 +810,7 @@ public class StringUtils {
             return string;
         }
         char paddingChar;
-        if (padding == null || padding.length() == 0) {
+        if (padding == null || padding.isEmpty()) {
             paddingChar = ' ';
         } else {
             paddingChar = padding.charAt(0);
@@ -941,7 +941,7 @@ public class StringUtils {
         }
         if (s == null) {
             return s;
-        } else if (s.length() == 0) {
+        } else if (s.isEmpty()) {
             return "";
         }
         int hash = s.hashCode();
@@ -1151,7 +1151,7 @@ public class StringUtils {
      * @return the escaped pattern
      */
     public static String escapeMetaDataPattern(String pattern) {
-        if (pattern == null || pattern.length() == 0) {
+        if (pattern == null || pattern.isEmpty()) {
             return pattern;
         }
         return replaceAll(pattern, "\\", "\\\\");

h2/src/main/org/h2/util/ToChar.java

@@ -362,13 +362,14 @@ public class ToChar {
         }
         int i = idx + 1;
         boolean allZeroes = true;
-        for (; i < numberStr.length(); i++) {
+        int length = numberStr.length();
+        for (; i < length; i++) {
             if (numberStr.charAt(i) != '0') {
                 allZeroes = false;
                 break;
             }
         }
-        final char[] zeroes = new char[allZeroes ? numberStr.length() - idx - 1: i - 1 - idx];
+        final char[] zeroes = new char[allZeroes ? length - idx - 1: i - 1 - idx];
         Arrays.fill(zeroes, '0');
         return String.valueOf(zeroes);
     }
@@ -688,7 +689,7 @@ public class ToChar {
         StringBuilder output = new StringBuilder();
         boolean fillMode = true;
 
-        for (int i = 0; i < format.length();) {
+        for (int i = 0, length = format.length(); i < length;) {
 
             Capitalization cap;
 

h2/src/main/org/h2/util/ToDateParser.java

@@ -249,7 +249,7 @@ public class ToDateParser {
     }
 
     private boolean hasToParseData() {
-        return formatStr.length() > 0;
+        return !formatStr.isEmpty();
     }
 
     private void removeFirstChar() {

h2/src/main/org/h2/util/ToDateTokenizer.java

@@ -651,7 +651,7 @@ class ToDateTokenizer {
          * @return the list of tokens, or {@code null}
          */
         static List<FormatTokenEnum> getTokensInQuestion(String formatStr) {
-            if (formatStr != null && formatStr.length() > 0) {
+            if (formatStr != null && !formatStr.isEmpty()) {
                 char key = Character.toUpperCase(formatStr.charAt(0));
                 if (key >= 'A' && key <= 'Y') {
                     List<FormatTokenEnum>[] tokens = TOKENS;

h2/src/main/org/h2/value/CompareMode.java

@@ -222,12 +222,13 @@ public class CompareMode implements Comparator<Value> {
         } else if (name.startsWith(CHARSET)) {
             return new CharsetCollator(Charset.forName(name.substring(CHARSET.length())));
         }
-        if (name.length() == 2) {
+        int length = name.length();
+        if (length == 2) {
             Locale locale = new Locale(StringUtils.toLowerEnglish(name), "");
             if (compareLocaleNames(locale, name)) {
                 result = Collator.getInstance(locale);
             }
-        } else if (name.length() == 5) {
+        } else if (length == 5) {
             // LL_CC (language_country)
             int idx = name.indexOf('_');
             if (idx >= 0) {

h2/src/main/org/h2/value/CompareModeIcu4J.java

@@ -49,12 +49,13 @@ public class CompareModeIcu4J extends CompareMode {
                     "com.ibm.icu.text.Collator");
             Method getInstanceMethod = collatorClass.getMethod(
                     "getInstance", Locale.class);
-            if (name.length() == 2) {
+            int length = name.length();
+            if (length == 2) {
                 Locale locale = new Locale(StringUtils.toLowerEnglish(name), "");
                 if (compareLocaleNames(locale, name)) {
                     result = (Comparator<String>) getInstanceMethod.invoke(null, locale);
                 }
-            } else if (name.length() == 5) {
+            } else if (length == 5) {
                 // LL_CC (language_country)
                 int idx = name.indexOf('_');
                 if (idx >= 0) {

h2/src/main/org/h2/value/ExtTypeInfoEnum.java

@@ -52,7 +52,7 @@ public final class ExtTypeInfoEnum extends ExtTypeInfo {
             }
             result.append('\'');
             String s = enumerators[i];
-            for (int j = 0; j < s.length(); j++) {
+            for (int j = 0, length = s.length(); j < length; j++) {
                 char c = s.charAt(j);
                 if (c == '\'') {
                     result.append('\'');

h2/src/main/org/h2/value/ValueLob.java

@@ -275,7 +275,7 @@ public class ValueLob extends Value {
 
     private static int getNewObjectId(DataHandler h) {
         String path = h.getDatabasePath();
-        if ((path != null) && (path.length() == 0)) {
+        if (path != null && path.isEmpty()) {
             path = new File(Utils.getProperty("java.io.tmpdir", "."),
                     SysProperties.PREFIX_TEMP_FILE).getAbsolutePath();
         }

h2/src/main/org/h2/value/ValueLobDb.java

@@ -176,7 +176,7 @@ public class ValueLobDb extends Value {
     private static String createTempLobFileName(DataHandler handler)
             throws IOException {
         String path = handler.getDatabasePath();
-        if (path.length() == 0) {
+        if (path.isEmpty()) {
             path = SysProperties.PREFIX_TEMP_FILE;
         }
         return FileUtils.createTempFile(path, Constants.SUFFIX_TEMP_FILE, true, true);

h2/src/main/org/h2/value/ValueStringFixed.java

@@ -47,13 +47,13 @@ public class ValueStringFixed extends ValueString {
     }
 
     private static String rightPadWithSpaces(String s, int length) {
-        int pad = length - s.length();
-        if (pad <= 0) {
+        int used = s.length();
+        if (length <= used) {
             return s;
         }
         char[] res = new char[length];
-        s.getChars(0, s.length(), res, 0);
-        Arrays.fill(res, s.length(), length, ' ');
+        s.getChars(0, used, res, 0);
+        Arrays.fill(res, used, length, ' ');
         return new String(res);
     }
 
@@ -109,11 +109,12 @@ public class ValueStringFixed extends ValueString {
             // Default behaviour of H2
             s = trimRight(s);
         }
-        if (s.length() == 0) {
+        int length = s.length();
+        if (length == 0) {
             return EMPTY;
         }
         ValueStringFixed obj = new ValueStringFixed(StringUtils.cache(s));
-        if (s.length() > SysProperties.OBJECT_CACHE_MAX_PER_ELEMENT_SIZE) {
+        if (length > SysProperties.OBJECT_CACHE_MAX_PER_ELEMENT_SIZE) {
             return obj;
         }
         return (ValueStringFixed) Value.cache(obj);

h2/src/main/org/h2/value/ValueStringIgnoreCase.java

@@ -60,11 +60,12 @@ public class ValueStringIgnoreCase extends ValueString {
      * @return the value
      */
     public static ValueStringIgnoreCase get(String s) {
-        if (s.length() == 0) {
+        int length = s.length();
+        if (length == 0) {
             return EMPTY;
         }
         ValueStringIgnoreCase obj = new ValueStringIgnoreCase(StringUtils.cache(s));
-        if (s.length() > SysProperties.OBJECT_CACHE_MAX_PER_ELEMENT_SIZE) {
+        if (length > SysProperties.OBJECT_CACHE_MAX_PER_ELEMENT_SIZE) {
             return obj;
         }
         ValueStringIgnoreCase cache = (ValueStringIgnoreCase) Value.cache(obj);