Do not use null keys in maps

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

@@ -107,7 +107,7 @@ public class AlterTableAddConstraint extends SchemaCommand {
             }
             throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, tableName);
         }
-        if (getSchema().findConstraint(session, constraintName) != null) {
+        if (constraintName != null && getSchema().findConstraint(session, constraintName) != null) {
             if (ifNotExists) {
                 return 0;
             }

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

@@ -69,7 +69,7 @@ public class CreateIndex extends SchemaCommand {
             }
             throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, tableName);
         }
-        if (getSchema().findIndex(session, indexName) != null) {
+        if (indexName != null && getSchema().findIndex(session, indexName) != null) {
             if (ifNotExists) {
                 return 0;
             }

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

@@ -82,7 +82,7 @@ import org.h2.util.TempFileDeleter;
 import org.h2.util.Utils;
 import org.h2.value.CaseInsensitiveMap;
 import org.h2.value.CompareMode;
-import org.h2.value.NullableKeyConcurrentMap;
+import org.h2.value.CaseInsensitiveConcurrentMap;
 import org.h2.value.Value;
 import org.h2.value.ValueInt;
 
@@ -3041,9 +3041,7 @@ public class Database implements DataHandler {
      * @return the hash map
      */
     public <V> HashMap<String, V> newStringMap() {
-        return dbSettings.databaseToUpper ?
-                new HashMap<String, V>() :
-                new CaseInsensitiveMap<V>();
+        return dbSettings.databaseToUpper ? new HashMap<String, V>() : new CaseInsensitiveMap<V>();
     }
 
     /**
@@ -3054,7 +3052,7 @@ public class Database implements DataHandler {
      * @return the hash map
      */
     public <V> ConcurrentHashMap<String, V> newConcurrentStringMap() {
-        return new NullableKeyConcurrentMap<>(!dbSettings.databaseToUpper);
+        return dbSettings.databaseToUpper ? new ConcurrentHashMap<String, V>() : new CaseInsensitiveConcurrentMap<V>();
     }
 
     /**

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

@@ -830,6 +830,9 @@ public class MetaTable extends Table {
             final ArrayList<Table> tablesToList;
             if (indexFrom != null && indexFrom.equals(indexTo)) {
                 String tableName = identifier(indexFrom.getString());
+                if (tableName == null) {
+                    break;
+                }
                 tablesToList = getTablesByName(session, tableName);
             } else {
                 tablesToList = getAllTables(session);
@@ -947,6 +950,9 @@ public class MetaTable extends Table {
             final ArrayList<Table> tablesToList;
             if (indexFrom != null && indexFrom.equals(indexTo)) {
                 String tableName = identifier(indexFrom.getString());
+                if (tableName == null) {
+                    break;
+                }
                 tablesToList = getTablesByName(session, tableName);
             } else {
                 tablesToList = getAllTables(session);

h2/src/main/org/h2/value/NullableKeyConcurrentMap.java → h2/src/main/org/h2/value/CaseInsensitiveConcurrentMap.java

@@ -10,53 +10,32 @@ import java.util.concurrent.ConcurrentHashMap;
 import org.h2.util.StringUtils;
 
 /**
- * A concurrent hash map with string keys that allows null keys.
+ * A concurrent hash map with case-insensitive string keys.
  *
  * @param <V> the value type
  */
-public class NullableKeyConcurrentMap<V> extends ConcurrentHashMap<String, V> {
+public class CaseInsensitiveConcurrentMap<V> extends ConcurrentHashMap<String, V> {
 
     private static final long serialVersionUID = 1L;
-    private static final String NULL = new String();
-
-    private final boolean toUpper;
-
-    /**
-     * Create new instance of map.
-     *
-     * @param toUpper
-     *                    whether keys should be converted to upper case
-     */
-    public NullableKeyConcurrentMap(boolean toUpper) {
-        this.toUpper = toUpper;
-    }
 
     @Override
     public V get(Object key) {
-        return super.get(toUpper(key));
+        return super.get(StringUtils.toUpperEnglish((String) key));
     }
 
     @Override
     public V put(String key, V value) {
-        return super.put(toUpper(key), value);
+        return super.put(StringUtils.toUpperEnglish(key), value);
     }
 
     @Override
     public boolean containsKey(Object key) {
-        return super.containsKey(toUpper(key));
+        return super.containsKey(StringUtils.toUpperEnglish((String) key));
     }
 
     @Override
     public V remove(Object key) {
-        return super.remove(toUpper(key));
-    }
-
-    private String toUpper(Object key) {
-        if (key == null) {
-            return NULL;
-        }
-        String s = key.toString();
-        return toUpper ? StringUtils.toUpperEnglish(s) : s;
+        return super.remove(StringUtils.toUpperEnglish((String) key));
     }
 
 }

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

@@ -19,26 +19,22 @@ public class CaseInsensitiveMap<V> extends HashMap<String, V> {
 
     @Override
     public V get(Object key) {
-        return super.get(toUpper(key));
+        return super.get(StringUtils.toUpperEnglish((String) key));
     }
 
     @Override
     public V put(String key, V value) {
-        return super.put(toUpper(key), value);
+        return super.put(StringUtils.toUpperEnglish(key), value);
     }
 
     @Override
     public boolean containsKey(Object key) {
-        return super.containsKey(toUpper(key));
+        return super.containsKey(StringUtils.toUpperEnglish((String) key));
     }
 
     @Override
     public V remove(Object key) {
-        return super.remove(toUpper(key));
-    }
-
-    private static String toUpper(Object key) {
-        return key == null ? null : StringUtils.toUpperEnglish(key.toString());
+        return super.remove(StringUtils.toUpperEnglish((String) key));
     }
 
 }