Remove converting to string using concatenation with empty string

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

@@ -924,7 +924,7 @@ public class Session extends SessionWithState implements TransactionStore.Rollba
                     if (!locks.contains(log.getTable())
                             && TableType.TABLE_LINK != tableType
                             && TableType.EXTERNAL_TABLE_ENGINE != tableType) {
-                        DbException.throwInternalError("" + tableType);
+                        DbException.throwInternalError(String.valueOf(tableType));
                     }
                 }
             }

h2/src/main/org/h2/index/PageBtreeIndex.java

@@ -51,7 +51,7 @@ public class PageBtreeIndex extends PageIndex {
         // trace.setLevel(TraceSystem.DEBUG);
         tableData = table;
         if (!database.isPersistent() || id < 0) {
-            throw DbException.throwInternalError("" + indexName);
+            throw DbException.throwInternalError(indexName);
         }
         this.store = database.getPageStore();
         store.addIndex(this);
@@ -154,7 +154,7 @@ public class PageBtreeIndex extends PageIndex {
             store.update(empty);
             return empty;
         } else if (!(p instanceof PageBtree)) {
-            throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "" + p);
+            throw DbException.get(ErrorCode.FILE_CORRUPTED_1, String.valueOf(p));
         }
         return (PageBtree) p;
     }

h2/src/main/org/h2/index/PageDataIndex.java

@@ -237,7 +237,7 @@ public class PageDataIndex extends PageIndex {
             store.update(empty);
             return empty;
         } else if (!(pd instanceof PageData)) {
-            throw DbException.get(ErrorCode.FILE_CORRUPTED_1, "" + pd);
+            throw DbException.get(ErrorCode.FILE_CORRUPTED_1, String.valueOf(pd));
         }
         PageData p = (PageData) pd;
         if (parent != -1) {

h2/src/main/org/h2/index/PageDataLeaf.java

@@ -153,7 +153,7 @@ public class PageDataLeaf extends PageData {
     private int findInsertionPoint(long key) {
         int x = find(key);
         if (x < entryCount && keys[x] == key) {
-            throw index.getDuplicateKeyException(""+key);
+            throw index.getDuplicateKeyException(String.valueOf(key));
         }
         return x;
     }

h2/src/main/org/h2/index/PageDelegateIndex.java

@@ -32,7 +32,7 @@ public class PageDelegateIndex extends PageIndex {
         this.initBaseIndex(table, id, name, cols, indexType);
         this.mainIndex = mainIndex;
         if (!database.isPersistent() || id < 0) {
-            throw DbException.throwInternalError("" + name);
+            throw DbException.throwInternalError(name);
         }
         PageStore store = database.getPageStore();
         store.addIndex(this);

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

@@ -1098,7 +1098,7 @@ public class JdbcConnection extends TraceObject
     private static JdbcSavepoint convertSavepoint(Savepoint savepoint) {
         if (!(savepoint instanceof JdbcSavepoint)) {
             throw DbException.get(ErrorCode.SAVEPOINT_IS_INVALID_1,
-                    "" + savepoint);
+                    String.valueOf(savepoint));
         }
         return (JdbcSavepoint) savepoint;
     }

h2/src/main/org/h2/mvstore/db/MVDelegateIndex.java

@@ -35,7 +35,7 @@ public class MVDelegateIndex extends BaseIndex implements MVIndex {
         this.initBaseIndex(table, id, name, cols, indexType);
         this.mainIndex = mainIndex;
         if (id < 0) {
-            throw DbException.throwInternalError("" + name);
+            throw DbException.throwInternalError(name);
         }
     }
 

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

@@ -301,7 +301,7 @@ public class WebApp {
                 for (Map.Entry<String, String> entry : map.entrySet()) {
                     String key = entry.getKey();
                     String value = entry.getValue();
-                    String type = "" + key.charAt(0);
+                    String type = String.valueOf(key.charAt(0));
                     if (Integer.parseInt(type) > 2) {
                         continue;
                     }
@@ -1182,14 +1182,14 @@ public class WebApp {
             rs.addRow("conn.getCatalog", conn.getCatalog());
             rs.addRow("conn.getAutoCommit", Boolean.toString(conn.getAutoCommit()));
             rs.addRow("conn.getTransactionIsolation", Integer.toString(conn.getTransactionIsolation()));
-            rs.addRow("conn.getWarnings", "" + conn.getWarnings());
+            rs.addRow("conn.getWarnings", String.valueOf(conn.getWarnings()));
             String map;
             try {
-                map = "" + conn.getTypeMap();
+                map = String.valueOf(conn.getTypeMap());
             } catch (SQLException e) {
                 map = e.toString();
             }
-            rs.addRow("conn.getTypeMap", "" + map);
+            rs.addRow("conn.getTypeMap", map);
             rs.addRow("conn.isReadOnly", Boolean.toString(conn.isReadOnly()));
             rs.addRow("conn.getHoldability", Integer.toString(conn.getHoldability()));
             addDatabaseMetaData(rs, meta);
@@ -1229,7 +1229,7 @@ public class WebApp {
             if (m.getParameterTypes().length == 0) {
                 try {
                     Object o = m.invoke(meta);
-                    rs.addRow("meta." + m.getName(), "" + o);
+                    rs.addRow("meta." + m.getName(), String.valueOf(o));
                 } catch (InvocationTargetException e) {
                     rs.addRow("meta." + m.getName(), e.getTargetException().toString());
                 } catch (Exception e) {

h2/src/main/org/h2/store/LobStorageMap.java

@@ -279,8 +279,7 @@ public class LobStorageMap implements LobStorageInterface {
             if (lob.getTableId() == LobStorageFrontend.TABLE_RESULT ||
                     lob.getTableId() == LobStorageFrontend.TABLE_ID_SESSION_VARIABLE) {
                 throw DbException.get(
-                        ErrorCode.LOB_CLOSED_ON_TIMEOUT_1, "" +
-                                lob.getLobId() + "/" + lob.getTableId());
+                        ErrorCode.LOB_CLOSED_ON_TIMEOUT_1, lob.getLobId() + "/" + lob.getTableId());
             }
             throw DbException.throwInternalError("Lob not found: " +
                     lob.getLobId() + "/" + lob.getTableId());

h2/src/main/org/h2/table/MetaTable.java

@@ -1764,11 +1764,11 @@ public class MetaTable extends Table {
                         // SELECTIVITY INT
                         Integer.toString(col.getSelectivity()),
                         // CHECK_CONSTRAINT
-                        "" + col.getCheckConstraintSQL(session, "VALUE"),
+                        col.getCheckConstraintSQL(session, "VALUE"),
                         // REMARKS
                         replaceNullWithEmpty(dt.getComment()),
                         // SQL
-                        "" + dt.getCreateSQL(),
+                        dt.getCreateSQL(),
                         // ID
                         Integer.toString(dt.getId())
                 );