diff --git a/src/main/java/com/alibaba/druid/pool/ha/MultiDataSourceConnection.java b/src/main/java/com/alibaba/druid/pool/ha/MultiDataSourceConnection.java
index 5d1f197049..846d7d5d96 100644
--- a/src/main/java/com/alibaba/druid/pool/ha/MultiDataSourceConnection.java
+++ b/src/main/java/com/alibaba/druid/pool/ha/MultiDataSourceConnection.java
@@ -633,7 +633,7 @@ public class MultiDataSourceConnection extends WrapperAdapter implements Connect
     public boolean isWrapperFor(Class<?> iface) throws SQLException {
         boolean result = super.isWrapperFor(iface);
 
-        if (result == false && conn != null) {
+        if ((!result) && conn != null) {
             result = conn.isWrapperFor(iface);
         }
 
diff --git a/src/main/java/com/alibaba/druid/pool/ha/cobar/CobarDataSource.java b/src/main/java/com/alibaba/druid/pool/ha/cobar/CobarDataSource.java
index 085c537e49..cb83ae2738 100644
--- a/src/main/java/com/alibaba/druid/pool/ha/cobar/CobarDataSource.java
+++ b/src/main/java/com/alibaba/druid/pool/ha/cobar/CobarDataSource.java
@@ -31,10 +31,10 @@ public class CobarDataSource extends MultiDataSource {
 
     private final static Log LOG                                   = LogFactory.getLog(CobarDataSource.class);
 
-    public static long       DEFAULT_FAILURE_DETECT_PERRIOD_MILLIS = 1000 * 3;                                // 3
-                                                                                                               // seconds
-    public static long       DEFAULT_CONFIG_LOAD_PERRIOD_MILLIS    = 1000 * 60 * 3;                           // 3
-                                                                                                               // minutes
+    public final static long DEFAULT_FAILURE_DETECT_PERRIOD_MILLIS = 1000 * 3;                                // 3
+    // seconds
+    public final static long DEFAULT_CONFIG_LOAD_PERRIOD_MILLIS    = 1000 * 60 * 3;                           // 3
+    // minutes
 
     private String           url;
 
@@ -50,7 +50,6 @@ public class CobarDataSource extends MultiDataSource {
     private List<Filter>     proxyFilters                          = new ArrayList<Filter>();
     private String           filters;
 
-
     public CobarDataSource(){
         this.setFailureDetector(new CobarFailureDetecter());
         this.setFailureDetectPeriodMillis(DEFAULT_FAILURE_DETECT_PERRIOD_MILLIS);
@@ -122,7 +121,7 @@ public class CobarDataSource extends MultiDataSource {
             if (this.getConfigLoader() == null) {
                 this.setConfigLoader(new CobarConfigLoader(this));
             }
-            
+
             final int RETRY_COUNT = 3;
             for (int i = 0; i < RETRY_COUNT; ++i) {
                 try {
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java
index fbaee61ff2..1c1fc3e891 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/hive/parser/HiveExprParser.java
@@ -16,12 +16,11 @@
 package com.alibaba.druid.sql.dialect.hive.parser;
 
 import com.alibaba.druid.sql.parser.Lexer;
-import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.parser.SQLExprParser;
 
 
 public class HiveExprParser extends SQLExprParser {
-    public HiveExprParser(String sql) throws ParserException{
+    public HiveExprParser(String sql) {
         super(new HiveLexer(sql));
         this.lexer.nextToken();
     }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlCreateTableParser.java b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlCreateTableParser.java
index 1a6c8c8ef5..0c70d275c3 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlCreateTableParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlCreateTableParser.java
@@ -32,7 +32,7 @@ import com.alibaba.druid.sql.parser.Token;
 
 public class MySqlCreateTableParser extends SQLCreateTableParser {
 
-    public MySqlCreateTableParser(String sql) throws ParserException{
+    public MySqlCreateTableParser(String sql) {
         super(new MySqlExprParser(sql));
     }
 
@@ -40,11 +40,11 @@ public class MySqlCreateTableParser extends SQLCreateTableParser {
         super(exprParser);
     }
 
-    public SQLCreateTableStatement parseCrateTable() throws ParserException {
+    public SQLCreateTableStatement parseCrateTable() {
         return parseCrateTable(true);
     }
 
-    public MySqlCreateTableStatement parseCrateTable(boolean acceptCreate) throws ParserException {
+    public MySqlCreateTableStatement parseCrateTable(boolean acceptCreate) {
         if (acceptCreate) {
             accept(Token.CREATE);
         }
@@ -182,7 +182,7 @@ public class MySqlCreateTableParser extends SQLCreateTableParser {
     }
 
     @SuppressWarnings("unused")
-    protected SQLTableConstaint parseConstraint() throws ParserException {
+    protected SQLTableConstaint parseConstraint() {
         SQLName name = null;
         if (lexer.token() == (Token.CONSTRAINT)) {
             lexer.nextToken();
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java
index 7d9a2e90a8..ccec633f7f 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlExprParser.java
@@ -52,12 +52,12 @@ public class MySqlExprParser extends SQLExprParser {
         super(lexer);
     }
 
-    public MySqlExprParser(String sql) throws ParserException{
+    public MySqlExprParser(String sql) {
         this(new MySqlLexer(sql));
         this.lexer.nextToken();
     }
 
-    public SQLExpr relationalRest(SQLExpr expr) throws ParserException {
+    public SQLExpr relationalRest(SQLExpr expr) {
         if (identifierEquals("REGEXP")) {
             lexer.nextToken();
             SQLExpr rightExp = equality();
@@ -79,7 +79,7 @@ public class MySqlExprParser extends SQLExprParser {
         return super.relationalRest(expr);
     }
 
-    public SQLExpr multiplicativeRest(SQLExpr expr) throws ParserException {
+    public SQLExpr multiplicativeRest(SQLExpr expr) {
         if (lexer.token() == Token.IDENTIFIER && "MOD".equalsIgnoreCase(lexer.stringVal())) {
             lexer.nextToken();
             SQLExpr rightExp = primary();
@@ -114,7 +114,7 @@ public class MySqlExprParser extends SQLExprParser {
         return super.notRationalRest(expr);
     }
 
-    public SQLExpr primary() throws ParserException {
+    public SQLExpr primary() {
         final Token tok = lexer.token();
         
         if (identifierEquals("outfile")) {
@@ -158,7 +158,7 @@ public class MySqlExprParser extends SQLExprParser {
 
     }
 
-    public final SQLExpr primaryRest(SQLExpr expr) throws ParserException {
+    public final SQLExpr primaryRest(SQLExpr expr) {
         if (expr == null) {
             throw new IllegalArgumentException("expr");
         }
@@ -489,7 +489,7 @@ public class MySqlExprParser extends SQLExprParser {
         }
     }
     
-    public SQLColumnDefinition parseColumn() throws ParserException {
+    public SQLColumnDefinition parseColumn() {
         MySqlSQLColumnDefinition column = new MySqlSQLColumnDefinition();
         column.setName(name());
         column.setDataType(parseDataType());
@@ -497,7 +497,7 @@ public class MySqlExprParser extends SQLExprParser {
         return parseColumnRest(column);
     }
 
-    public SQLColumnDefinition parseColumnRest(SQLColumnDefinition column) throws ParserException {
+    public SQLColumnDefinition parseColumnRest(SQLColumnDefinition column) {
         if (identifierEquals("AUTO_INCREMENT")) {
             lexer.nextToken();
             if (column instanceof MySqlSQLColumnDefinition) {
@@ -514,7 +514,7 @@ public class MySqlExprParser extends SQLExprParser {
         return column;
     }
     
-    public SQLExpr orRest(SQLExpr expr) throws ParserException {
+    public SQLExpr orRest(SQLExpr expr) {
 
         for (;;) {
             if (lexer.token() == Token.OR || lexer.token() == Token.BARBAR) {
@@ -566,7 +566,7 @@ public class MySqlExprParser extends SQLExprParser {
         return item;
     }
     
-    public SQLName nameRest(SQLName name) throws ParserException {
+    public SQLName nameRest(SQLName name) {
         if (lexer.token() == Token.VARIANT && "@".equals(lexer.stringVal())) {
             lexer.nextToken();
             MySqlUserName userName = new MySqlUserName();
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java
index bfb313c360..bb39281bd1 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java
@@ -44,12 +44,12 @@ public class MySqlSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
-    public MySqlSelectParser(String sql) throws ParserException{
+    public MySqlSelectParser(String sql) {
         this(new MySqlExprParser(sql));
     }
 
     @Override
-    public SQLSelectQuery query() throws ParserException {
+    public SQLSelectQuery query() {
         if (lexer.token() == (Token.LPAREN)) {
             lexer.nextToken();
 
@@ -220,7 +220,7 @@ public class MySqlSelectParser extends SQLSelectParser {
         return queryRest(queryBlock);
     }
 
-    protected void parseGroupBy(SQLSelectQueryBlock queryBlock) throws ParserException {
+    protected void parseGroupBy(SQLSelectQueryBlock queryBlock) {
         if (lexer.token() == (Token.GROUP)) {
             lexer.nextToken();
             accept(Token.BY);
@@ -255,7 +255,7 @@ public class MySqlSelectParser extends SQLSelectParser {
         }
     }
 
-    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) throws ParserException {
+    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) {
         if (identifierEquals("USING")) {
             return tableSource;
         }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java
index bc72d2587b..d8593d197e 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java
@@ -144,7 +144,7 @@ public class MySqlStatementParser extends SQLStatementParser {
     private static final String DELAYED      = "DELAYED";
     private static final String LOW_PRIORITY = "LOW_PRIORITY";
 
-    public MySqlStatementParser(String sql) throws ParserException{
+    public MySqlStatementParser(String sql) {
         super(new MySqlExprParser(sql));
     }
 
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleExprParser.java
index 9fd2d59321..d082300261 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleExprParser.java
@@ -91,7 +91,7 @@ public class OracleExprParser extends SQLExprParser {
         this.lexer.nextToken();
     }
     
-    public SQLDataType parseDataType() throws ParserException {
+    public SQLDataType parseDataType() {
         
         if (lexer.token() == Token.DEFAULT || lexer.token() == Token.NOT || lexer.token() == Token.NULL) {
             return null;
@@ -127,7 +127,7 @@ public class OracleExprParser extends SQLExprParser {
         return false;
     }
 
-    public SQLExpr primary() throws ParserException {
+    public SQLExpr primary() {
         final Token tok = lexer.token();
 
         SQLExpr sqlExpr = null;
@@ -302,7 +302,7 @@ public class OracleExprParser extends SQLExprParser {
         return super.methodRest(expr, false);
     }
 
-    public SQLExpr primaryRest(SQLExpr expr) throws ParserException {
+    public SQLExpr primaryRest(SQLExpr expr) {
         if (lexer.token() == Token.IDENTIFIER && expr instanceof SQLNumericLiteralExpr) {
             String ident = lexer.stringVal();
             if (ident.length() == 1) {
@@ -729,7 +729,7 @@ public class OracleExprParser extends SQLExprParser {
         return interval;    
     }
     
-    public SQLExpr relationalRest(SQLExpr expr) throws ParserException {
+    public SQLExpr relationalRest(SQLExpr expr) {
         if (lexer.token() == Token.IS) {
             lexer.nextToken();
             
@@ -752,7 +752,7 @@ public class OracleExprParser extends SQLExprParser {
     }
     
     
-    public SQLName name() throws ParserException {
+    public SQLName name() {
         SQLName name = super.name();
         
         if (lexer.token() == Token.MONKEYS_AT) {
@@ -770,7 +770,7 @@ public class OracleExprParser extends SQLExprParser {
         return name;
     }
     
-    public SQLExpr equalityRest(SQLExpr expr) throws ParserException {
+    public SQLExpr equalityRest(SQLExpr expr) {
         SQLExpr rightExp;
         if (lexer.token() == Token.EQ) {
             lexer.nextToken();
@@ -828,7 +828,7 @@ public class OracleExprParser extends SQLExprParser {
         return column;
     }
     
-    public SQLExpr exprRest(SQLExpr expr) throws ParserException {
+    public SQLExpr exprRest(SQLExpr expr) {
         expr = super.exprRest(expr);
         
         if (lexer.token() == Token.COLONEQ) {
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java
index 94dfc06e2f..0c0456d5db 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java
@@ -620,7 +620,7 @@ public class OracleSelectParser extends SQLSelectParser {
         }
     }
 
-    protected String as() throws ParserException {
+    protected String as() {
         if (lexer.token() == Token.CONNECT) {
             return null;
         }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleStatementParser.java b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleStatementParser.java
index 3dcab87096..04e5f86ad5 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleStatementParser.java
@@ -130,11 +130,11 @@ public class OracleStatementParser extends SQLStatementParser {
     }
 
     @Override
-    public void parseStatementList(List<SQLStatement> statementList) throws ParserException {
+    public void parseStatementList(List<SQLStatement> statementList) {
         parseStatementList(statementList, -1);
     }
 
-    public void parseStatementList(List<SQLStatement> statementList, int max) throws ParserException {
+    public void parseStatementList(List<SQLStatement> statementList, int max) {
         for (;;) {
             if (max != -1) {
                 if (statementList.size() >= max) {
@@ -1106,7 +1106,7 @@ public class OracleStatementParser extends SQLStatementParser {
         return new OracleSelectParser(this.exprParser);
     }
 
-    public OracleMergeStatement parseMerge() throws ParserException {
+    public OracleMergeStatement parseMerge() {
         accept(Token.MERGE);
 
         OracleMergeStatement stmt = new OracleMergeStatement();
@@ -1410,7 +1410,7 @@ public class OracleStatementParser extends SQLStatementParser {
         return stmt;
     }
 
-    public OracleDeleteStatement parseDeleteStatement() throws ParserException {
+    public OracleDeleteStatement parseDeleteStatement() {
         OracleDeleteStatement deleteStatement = new OracleDeleteStatement();
 
         if (lexer.token() == Token.DELETE) {
@@ -1595,7 +1595,7 @@ public class OracleStatementParser extends SQLStatementParser {
         return stmt;
     }
 
-    public SQLUpdateStatement parseUpdateStatement() throws ParserException {
+    public SQLUpdateStatement parseUpdateStatement() {
         return new OracleUpdateParser(this.lexer).parseUpdateStatement();
     }
 }
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleUpdateParser.java b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleUpdateParser.java
index a4ff445455..2859c2801e 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleUpdateParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleUpdateParser.java
@@ -27,7 +27,7 @@ import com.alibaba.druid.sql.parser.Token;
 
 public class OracleUpdateParser extends SQLStatementParser {
 
-    public OracleUpdateParser(String sql) throws ParserException{
+    public OracleUpdateParser(String sql) {
         super(new OracleExprParser(sql));
     }
 
@@ -35,7 +35,7 @@ public class OracleUpdateParser extends SQLStatementParser {
         super(new OracleExprParser(lexer));
     }
 
-    public OracleUpdateStatement parseUpdateStatement() throws ParserException {
+    public OracleUpdateStatement parseUpdateStatement() {
         OracleUpdateStatement update = new OracleUpdateStatement();
         
         if (lexer.token() == Token.UPDATE) {
@@ -66,13 +66,13 @@ public class OracleUpdateParser extends SQLStatementParser {
         return update;
     }
 
-    private void parseErrorLoging(OracleUpdateStatement update) throws ParserException {
+    private void parseErrorLoging(OracleUpdateStatement update) {
         if (identifierEquals("LOG")) {
             throw new ParserException("TODO");
         }
     }
 
-    private void parseReturn(OracleUpdateStatement update) throws ParserException {
+    private void parseReturn(OracleUpdateStatement update) {
         if (identifierEquals("RETURN") || lexer.token() == Token.RETURNING) {
             lexer.nextToken();
 
@@ -104,20 +104,20 @@ public class OracleUpdateParser extends SQLStatementParser {
         }
     }
 
-    private void parseHints(OracleUpdateStatement update) throws ParserException {
+    private void parseHints(OracleUpdateStatement update) {
         if (lexer.token() == Token.HINT) {
             throw new ParserException("TODO");
         }
     }
 
-    private void parseWhere(OracleUpdateStatement update) throws ParserException {
+    private void parseWhere(OracleUpdateStatement update) {
         if (lexer.token() == (Token.WHERE)) {
             lexer.nextToken();
             update.setWhere(this.exprParser.expr());
         }
     }
 
-    private void parseSet(OracleUpdateStatement update) throws ParserException {
+    private void parseSet(OracleUpdateStatement update) {
         accept(Token.SET);
 
         for (;;) {
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
index 545bf999bc..da82e8deba 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGExprParser.java
@@ -20,12 +20,11 @@ import com.alibaba.druid.sql.dialect.postgresql.ast.PGAggregateExpr;
 import com.alibaba.druid.sql.dialect.postgresql.ast.PGOrderBy;
 import com.alibaba.druid.sql.dialect.postgresql.ast.expr.PGAnalytic;
 import com.alibaba.druid.sql.parser.Lexer;
-import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.parser.SQLExprParser;
 import com.alibaba.druid.sql.parser.Token;
 
 public class PGExprParser extends SQLExprParser{
-    public PGExprParser(String sql) throws ParserException{
+    public PGExprParser(String sql) {
         super(new PGLexer(sql));
         this.lexer.nextToken();
     }
@@ -34,7 +33,7 @@ public class PGExprParser extends SQLExprParser{
         super(lexer);
     }
     
-    protected SQLAggregateExpr parseAggregateExpr(String methodName) throws ParserException {
+    protected SQLAggregateExpr parseAggregateExpr(String methodName)  {
         methodName = methodName.toUpperCase();
         
         PGAggregateExpr aggregateExpr;
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSQLStatementParser.java b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSQLStatementParser.java
index 7a5ff5ec38..c0c3cd4c47 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSQLStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSQLStatementParser.java
@@ -40,7 +40,7 @@ import com.alibaba.druid.sql.parser.Token;
 
 public class PGSQLStatementParser extends SQLStatementParser {
 
-    public PGSQLStatementParser(String sql) throws ParserException{
+    public PGSQLStatementParser(String sql) {
         super (new PGExprParser(sql));
     }
 
@@ -52,7 +52,7 @@ public class PGSQLStatementParser extends SQLStatementParser {
         return new PGSelectParser(this.exprParser);
     }
 
-    public SQLUpdateStatement parseUpdateStatement() throws ParserException {
+    public SQLUpdateStatement parseUpdateStatement() {
         accept(Token.UPDATE);
 
         PGUpdateStatement udpateStatement = new PGUpdateStatement();
@@ -150,7 +150,7 @@ public class PGSQLStatementParser extends SQLStatementParser {
         return stmt;
     }
 
-    public PGDeleteStatement parseDeleteStatement() throws ParserException {
+    public PGDeleteStatement parseDeleteStatement() {
         lexer.nextToken();
         PGDeleteStatement deleteStatement = new PGDeleteStatement();
 
@@ -329,7 +329,7 @@ public class PGSQLStatementParser extends SQLStatementParser {
         return withQuery;
     }
 
-    public PGSelectStatement parseSelect() throws ParserException {
+    public PGSelectStatement parseSelect() {
         return new PGSelectStatement(createSQLSelectParser().select());
     }
 
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSelectParser.java b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSelectParser.java
index 4a0fe68299..ea8ba54d86 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSelectParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSelectParser.java
@@ -38,7 +38,7 @@ public class PGSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
-    public PGSelectParser(String sql) throws ParserException{
+    public PGSelectParser(String sql) {
         this(new PGExprParser(sql));
     }
 
@@ -47,7 +47,7 @@ public class PGSelectParser extends SQLSelectParser {
     }
 
     @Override
-    public SQLSelectQuery query() throws ParserException {
+    public SQLSelectQuery query() {
         PGSelectQueryBlock queryBlock = new PGSelectQueryBlock();
 
         if (lexer.token() == Token.SELECT) {
@@ -219,7 +219,7 @@ public class PGSelectParser extends SQLSelectParser {
         return queryRest(queryBlock);
     }
 
-    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) throws ParserException {
+    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) {
         if (lexer.token() == Token.AS && tableSource instanceof SQLExprTableSource) {
             String alias = this.as();
 
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerExprParser.java b/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerExprParser.java
index 43f699df5d..5c58cb8c91 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerExprParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerExprParser.java
@@ -20,7 +20,6 @@ import com.alibaba.druid.sql.ast.SQLName;
 import com.alibaba.druid.sql.ast.expr.SQLPropertyExpr;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.expr.SQLServerObjectReferenceExpr;
 import com.alibaba.druid.sql.parser.Lexer;
-import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.parser.SQLExprParser;
 import com.alibaba.druid.sql.parser.Token;
 
@@ -30,12 +29,12 @@ public class SQLServerExprParser extends SQLExprParser {
         super(lexer);
     }
 
-    public SQLServerExprParser(String sql) throws ParserException{
+    public SQLServerExprParser(String sql) {
         super(new SQLServerLexer(sql));
         this.lexer.nextToken();
     }
 
-    public SQLExpr primaryRest(SQLExpr expr) throws ParserException {
+    public SQLExpr primaryRest(SQLExpr expr) {
         if (lexer.token() == Token.DOTDOT) {
             expr = nameRest((SQLName) expr);
         }
@@ -43,7 +42,7 @@ public class SQLServerExprParser extends SQLExprParser {
         return super.primaryRest(expr);
     }
     
-    public SQLName nameRest(SQLName expr) throws ParserException {
+    public SQLName nameRest(SQLName expr) {
         if (lexer.token() == Token.DOTDOT) {
             lexer.nextToken();
             String text = lexer.stringVal();
diff --git a/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java b/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java
index 9a06a3ce4f..6fae0bb0ad 100644
--- a/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java
+++ b/src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java
@@ -21,7 +21,6 @@ import com.alibaba.druid.sql.ast.statement.SQLSelectQuery;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerSelect;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.Top;
-import com.alibaba.druid.sql.parser.ParserException;
 import com.alibaba.druid.sql.parser.SQLExprParser;
 import com.alibaba.druid.sql.parser.SQLSelectParser;
 import com.alibaba.druid.sql.parser.Token;
@@ -36,7 +35,7 @@ public class SQLServerSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
-    public SQLSelect select() throws ParserException {
+    public SQLSelect select()  {
         SQLServerSelect select = new SQLServerSelect();
 
         select.setQuery(query());
@@ -49,7 +48,7 @@ public class SQLServerSelectParser extends SQLSelectParser {
         return select;
     }
 
-    public SQLSelectQuery query() throws ParserException {
+    public SQLSelectQuery query()  {
         if (lexer.token() == Token.LPAREN) {
             lexer.nextToken();
 
diff --git a/src/main/java/com/alibaba/druid/sql/parser/Lexer.java b/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
index 525a9e9368..12ccd10a33 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/Lexer.java
@@ -178,12 +178,6 @@ public class Lexer {
         token = ERROR;
     }
 
-    /**
-     * Report an error at the current token position using the provided arguments.
-     */
-    private void lexError(String key, Object... args) {
-        lexError(tokenPos, key, args);
-    }
 
     /**
      * Return the current token, set by nextToken().
@@ -376,7 +370,7 @@ public class Lexer {
                         token = EOF;
                         tokenPos = bp = eofPos;
                     } else {
-                        lexError("illegal.char", String.valueOf((int) ch));
+                        lexError(tokenPos, "illegal.char", String.valueOf((int) ch));
                         scanChar();
                     }
 
diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLParser.java b/src/main/java/com/alibaba/druid/sql/parser/SQLParser.java
index 2434890423..0f4ea9da03 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLParser.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLParser.java
@@ -45,7 +45,7 @@ public class SQLParser {
         }
     }
 
-    protected String as() throws ParserException {
+    protected String as()  {
         String alias = null;
 
         if (lexer.token() == Token.AS) {
diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java b/src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java
index 17e56e411a..f758edd7c2 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java
@@ -46,7 +46,7 @@ public class SQLSelectParser extends SQLParser {
         this.exprParser = exprParser;
     }
 
-    public SQLSelect select() throws ParserException {
+    public SQLSelect select() {
         SQLSelect select = new SQLSelect();
 
         select.setQuery(query());
@@ -72,7 +72,7 @@ public class SQLSelectParser extends SQLParser {
         return union;
     }
 
-    public SQLSelectQuery queryRest(SQLSelectQuery selectQuery) throws ParserException {
+    public SQLSelectQuery queryRest(SQLSelectQuery selectQuery) {
         if (lexer.token() == Token.UNION) {
             lexer.nextToken();
 
@@ -123,7 +123,7 @@ public class SQLSelectParser extends SQLParser {
         return selectQuery;
     }
 
-    public SQLSelectQuery query() throws ParserException {
+    public SQLSelectQuery query() {
         if (lexer.token() == Token.LPAREN) {
             lexer.nextToken();
 
@@ -159,7 +159,7 @@ public class SQLSelectParser extends SQLParser {
         return queryRest(queryBlock);
     }
 
-    protected void parseWhere(SQLSelectQueryBlock queryBlock) throws ParserException {
+    protected void parseWhere(SQLSelectQueryBlock queryBlock) {
         if (lexer.token() == Token.WHERE) {
             lexer.nextToken();
 
@@ -167,7 +167,7 @@ public class SQLSelectParser extends SQLParser {
         }
     }
 
-    protected void parseGroupBy(SQLSelectQueryBlock queryBlock) throws ParserException {
+    protected void parseGroupBy(SQLSelectQueryBlock queryBlock) {
         if (lexer.token() == Token.GROUP) {
             lexer.nextToken();
             accept(Token.BY);
@@ -198,7 +198,7 @@ public class SQLSelectParser extends SQLParser {
         }
     }
 
-    protected void parseSelectList(SQLSelectQueryBlock queryBlock) throws ParserException {
+    protected void parseSelectList(SQLSelectQueryBlock queryBlock) {
         queryBlock.getSelectList().add(new SQLSelectItem(expr(), as()));
 
         while (lexer.token() == Token.COMMA) {
@@ -207,7 +207,7 @@ public class SQLSelectParser extends SQLParser {
         }
     }
 
-    public void parseFrom(SQLSelectQueryBlock queryBlock) throws ParserException {
+    public void parseFrom(SQLSelectQueryBlock queryBlock) {
         if (lexer.token() != Token.FROM) {
             return;
         }
@@ -217,7 +217,7 @@ public class SQLSelectParser extends SQLParser {
         queryBlock.setFrom(parseTableSource());
     }
 
-    public SQLTableSource parseTableSource() throws ParserException {
+    public SQLTableSource parseTableSource() {
         if (lexer.token() == Token.LPAREN) {
             lexer.nextToken();
             SQLTableSource tableSource;
@@ -248,7 +248,7 @@ public class SQLSelectParser extends SQLParser {
         return parseTableSourceRest(tableReference);
     }
 
-    private void parseTableSourceQueryTableExpr(SQLExprTableSource tableReference) throws ParserException {
+    private void parseTableSourceQueryTableExpr(SQLExprTableSource tableReference) {
         if (lexer.token() == Token.LITERAL_ALIAS || lexer.token() == Token.IDENTIFIED
             || lexer.token() == Token.LITERAL_CHARS) {
             tableReference.setExpr(this.exprParser.name());
@@ -258,7 +258,7 @@ public class SQLSelectParser extends SQLParser {
         tableReference.setExpr(expr());
     }
 
-    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) throws ParserException {
+    protected SQLTableSource parseTableSourceRest(SQLTableSource tableSource) {
         if ((tableSource.getAlias() == null) || (tableSource.getAlias().length() == 0)) {
             if (lexer.token() != Token.LEFT && lexer.token() != Token.RIGHT && lexer.token() != Token.FULL) {
                 String alias = as();
@@ -329,7 +329,7 @@ public class SQLSelectParser extends SQLParser {
         return this.exprParser.expr();
     }
 
-    public SQLOrderBy parseOrderBy() throws ParserException {
+    public SQLOrderBy parseOrderBy() {
         return this.exprParser.parseOrderBy();
     }
 
diff --git a/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java b/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
index 02632ca53e..3538278fb4 100644
--- a/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
+++ b/src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java
@@ -63,13 +63,13 @@ public class SQLStatementParser extends SQLParser {
         return exprParser;
     }
 
-    public List<SQLStatement> parseStatementList() throws ParserException {
+    public List<SQLStatement> parseStatementList() {
         List<SQLStatement> statementList = new ArrayList<SQLStatement>();
         parseStatementList(statementList);
         return statementList;
     }
 
-    public void parseStatementList(List<SQLStatement> statementList) throws ParserException {
+    public void parseStatementList(List<SQLStatement> statementList) {
         for (;;) {
             if (lexer.token() == Token.EOF) {
                 return;
@@ -408,11 +408,11 @@ public class SQLStatementParser extends SQLParser {
         return false;
     }
 
-    public SQLStatement parseDropUser() throws ParserException {
+    public SQLStatement parseDropUser() {
         throw new ParserException("TODO " + lexer.token());
     }
 
-    public SQLStatement parseDropIndex() throws ParserException {
+    public SQLStatement parseDropIndex() {
         accept(Token.INDEX);
         SQLDropIndexStatement stmt = new SQLDropIndexStatement();
         stmt.setIndexName(this.exprParser.name());
@@ -421,7 +421,7 @@ public class SQLStatementParser extends SQLParser {
         return stmt;
     }
 
-    public SQLCallStatement parseCall() throws ParserException {
+    public SQLCallStatement parseCall() {
 
         boolean brace = false;
         if (lexer.token() == Token.LBRACE) {
@@ -447,7 +447,7 @@ public class SQLStatementParser extends SQLParser {
         return stmt;
     }
 
-    public SQLStatement parseSet() throws ParserException {
+    public SQLStatement parseSet() {
         accept(Token.SET);
         SQLSetStatement stmt = new SQLSetStatement();
 
@@ -470,7 +470,7 @@ public class SQLStatementParser extends SQLParser {
         }
     }
 
-    public SQLStatement parseCreate() throws ParserException {
+    public SQLStatement parseCreate() {
         char mark_ch = lexer.current();
         int mark_bp = lexer.bp();
 
@@ -530,7 +530,7 @@ public class SQLStatementParser extends SQLParser {
         return new SQLCreateTableParser(this.exprParser);
     }
 
-    public SQLSelectStatement parseSelect() throws ParserException {
+    public SQLSelectStatement parseSelect() {
         return new SQLSelectStatement(createSQLSelectParser().select());
     }
 
@@ -538,7 +538,7 @@ public class SQLStatementParser extends SQLParser {
         return new SQLSelectParser(this.exprParser);
     }
 
-    public SQLUpdateStatement parseUpdateStatement() throws ParserException {
+    public SQLUpdateStatement parseUpdateStatement() {
         SQLUpdateStatement udpateStatement = createUpdateStatement();
 
         if (lexer.token() == Token.UPDATE) {
@@ -578,7 +578,7 @@ public class SQLStatementParser extends SQLParser {
         return new SQLUpdateStatement();
     }
 
-    public SQLDeleteStatement parseDeleteStatement() throws ParserException {
+    public SQLDeleteStatement parseDeleteStatement() {
         SQLDeleteStatement deleteStatement = new SQLDeleteStatement();
 
         if (lexer.token() == Token.DELETE) {
@@ -601,13 +601,13 @@ public class SQLStatementParser extends SQLParser {
         return deleteStatement;
     }
 
-    public SQLCreateTableStatement parseCreateTable() throws ParserException {
+    public SQLCreateTableStatement parseCreateTable() {
         // SQLCreateTableParser parser = new SQLCreateTableParser(this.lexer);
         // return parser.parseCrateTable();
         throw new ParserException("TODO");
     }
 
-    public SQLCreateViewStatement parseCreateView() throws ParserException {
+    public SQLCreateViewStatement parseCreateView() {
         SQLCreateViewStatement createView = new SQLCreateViewStatement();
 
         this.accept(Token.CREATE);
diff --git a/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java b/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
index 1fe690de1a..61782a2484 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
@@ -218,8 +218,6 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
         }
 
         public boolean visit(SQLIdentifierExpr x) {
-            String currentTable = getCurrentTable();
-
             if (subQueryMap.containsKey(currentTable)) {
                 return false;
             }
@@ -252,13 +250,13 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
 
         public void addOrderByColumn(String table, String columnName, SQLObject expr) {
             Column column = new Column(table, columnName);
-            
+
             SQLObject parent = expr.getParent();
             if (parent instanceof SQLSelectOrderByItem) {
                 SQLOrderingSpecification type = ((SQLSelectOrderByItem) parent).getType();
                 column.getAttributes().put("orderBy.type", type);
             }
-            
+
             orderByColumns.add(column);
         }
     }
@@ -421,12 +419,10 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
 
             String column = ((SQLIdentifierExpr) expr).getName();
             String table = getCurrentTable();
-            if (table != null) {
-                if (aliasMap.containsKey(table)) {
-                    table = aliasMap.get(table);
-                    if (table == null) {
-                        return null;
-                    }
+            if (table != null && aliasMap.containsKey(table)) {
+                table = aliasMap.get(table);
+                if (table == null) {
+                    return null;
                 }
             }
 
@@ -548,14 +544,12 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
             return false;
         }
 
-        if (x.getInto() != null) {
-            if (x.getInto().getExpr() instanceof SQLName) {
-                SQLName into = (SQLName) x.getInto().getExpr();
-                String ident = into.toString();
-                TableStat stat = getTableStat(ident);
-                if (stat != null) {
-                    stat.incrementInsertCount();
-                }
+        if (x.getInto() != null && x.getInto().getExpr() instanceof SQLName) {
+            SQLName into = (SQLName) x.getInto().getExpr();
+            String ident = into.toString();
+            TableStat stat = getTableStat(ident);
+            if (stat != null) {
+                stat.incrementInsertCount();
             }
         }
 
@@ -746,11 +740,9 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
         SQLSelectQuery query = x.getSelect().getQuery();
 
         Map<String, String> aliasMap = getAliasMap();
-        if (aliasMap != null) {
-            if (x.getAlias() != null) {
-                aliasMap.put(x.getAlias(), null);
-                subQueryMap.put(x.getAlias(), query);
-            }
+        if (aliasMap != null && x.getAlias() != null) {
+            aliasMap.put(x.getAlias(), null);
+            subQueryMap.put(x.getAlias(), query);
         }
         return false;
     }
@@ -911,7 +903,7 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
     }
 
     public void endVisit(SQLDeleteStatement x) {
-        
+
     }
 
     public void endVisit(SQLUpdateStatement x) {
diff --git a/src/main/java/com/alibaba/druid/stat/DruidStatManagerFacade.java b/src/main/java/com/alibaba/druid/stat/DruidStatManagerFacade.java
index a4886a56f6..1891eb4092 100644
--- a/src/main/java/com/alibaba/druid/stat/DruidStatManagerFacade.java
+++ b/src/main/java/com/alibaba/druid/stat/DruidStatManagerFacade.java
@@ -45,7 +45,7 @@ import com.alibaba.druid.util.StringUtils;
  * 
  * @author sandzhang<sandzhangtoo@gmail.com>
  */
-public class DruidStatManagerFacade {
+public final class DruidStatManagerFacade {
 
     private final static DruidStatManagerFacade instance    = new DruidStatManagerFacade();
     private boolean                             resetEnable = true;
diff --git a/src/main/java/com/alibaba/druid/stat/DruidStatService.java b/src/main/java/com/alibaba/druid/stat/DruidStatService.java
index 2d4b864481..1b510e0804 100644
--- a/src/main/java/com/alibaba/druid/stat/DruidStatService.java
+++ b/src/main/java/com/alibaba/druid/stat/DruidStatService.java
@@ -44,7 +44,7 @@ import com.alibaba.druid.util.StringUtils;
  * 
  * @author sandzhang<sandzhangtoo@gmail.com>
  */
-public class DruidStatService implements DruidStatServiceMBean {
+public final class DruidStatService implements DruidStatServiceMBean {
 
     private final static Log              LOG                    = LogFactory.getLog(DruidStatService.class);
 
diff --git a/src/main/java/com/alibaba/druid/stat/JdbcStatManager.java b/src/main/java/com/alibaba/druid/stat/JdbcStatManager.java
index 386462d736..6cd73b3653 100644
--- a/src/main/java/com/alibaba/druid/stat/JdbcStatManager.java
+++ b/src/main/java/com/alibaba/druid/stat/JdbcStatManager.java
@@ -34,7 +34,7 @@ import com.alibaba.druid.pool.DruidDataSource;
 import com.alibaba.druid.proxy.DruidDriver;
 import com.alibaba.druid.proxy.jdbc.DataSourceProxyImpl;
 
-public class JdbcStatManager implements JdbcStatManagerMBean {
+public final class JdbcStatManager implements JdbcStatManagerMBean {
 
     private final AtomicLong                                sqlIdSeed      = new AtomicLong(1000);
 
diff --git a/src/main/java/com/alibaba/druid/support/http/WebStatFilter.java b/src/main/java/com/alibaba/druid/support/http/WebStatFilter.java
index 8dc1c633d7..33d23f83e8 100644
--- a/src/main/java/com/alibaba/druid/support/http/WebStatFilter.java
+++ b/src/main/java/com/alibaba/druid/support/http/WebStatFilter.java
@@ -16,7 +16,6 @@
 package com.alibaba.druid.support.http;
 
 import java.io.IOException;
-import java.io.PrintWriter;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
@@ -510,9 +509,5 @@ public class WebStatFilter implements Filter {
         public int getStatus() {
             return status;
         }
-
-        public PrintWriter getWriter() throws IOException {
-            return super.getWriter();
-        }
     }
 }
diff --git a/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java b/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
index 712784ca3f..839e1ebae0 100644
--- a/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
+++ b/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
@@ -706,7 +706,7 @@ public class WebAppStat {
             } else if (userAgent.indexOf("FreeBSD") != -1) {
                 osFreeBSDCount.incrementAndGet();
                 isBSD = true;
-            } else if (isLinux == false && userAgent.indexOf("Linux") != -1) {
+            } else if ((!isLinux) && userAgent.indexOf("Linux") != -1) {
                 osLinuxCount.incrementAndGet();
                 isLinux = true;
             }
diff --git a/src/main/java/com/alibaba/druid/support/jconsole/DruidSQLPanel.java b/src/main/java/com/alibaba/druid/support/jconsole/DruidSQLPanel.java
index 60e3063e26..81ad7703c3 100644
--- a/src/main/java/com/alibaba/druid/support/jconsole/DruidSQLPanel.java
+++ b/src/main/java/com/alibaba/druid/support/jconsole/DruidSQLPanel.java
@@ -91,7 +91,6 @@ public class DruidSQLPanel extends DruidPanel {
     		add("FetchRowCountHistogram");
     	}
     };  
-    private RowHeaderTable header;
 
 	public DruidSQLPanel() {
 		super();
@@ -104,7 +103,7 @@ public class DruidSQLPanel extends DruidPanel {
 		tableModel = new DruidTableModel(data,SHOW_LIST);
 		table.setModel(tableModel);
 		
-		header = new RowHeaderTable(table,20);
+		RowHeaderTable header = new RowHeaderTable(table,20);
 		scrollPane.setRowHeaderView(header);
 	}   
 }
diff --git a/src/main/java/com/alibaba/druid/support/logging/Resources.java b/src/main/java/com/alibaba/druid/support/logging/Resources.java
index 68f5dbcc8e..8adc0fa605 100644
--- a/src/main/java/com/alibaba/druid/support/logging/Resources.java
+++ b/src/main/java/com/alibaba/druid/support/logging/Resources.java
@@ -28,7 +28,7 @@ import java.util.Properties;
 /**
  * A class to simplify access to resources through the classloader.
  */
-public class Resources extends Object {
+public final class Resources extends Object {
 
     private static ClassLoader defaultClassLoader;
 
@@ -79,7 +79,7 @@ public class Resources extends Object {
      */
     public static URL getResourceURL(ClassLoader loader, String resource) throws IOException {
         URL url = null;
-        
+
         if (loader != null) {
             url = loader.getResource(resource);
         }
@@ -87,11 +87,11 @@ public class Resources extends Object {
         if (url == null) {
             url = ClassLoader.getSystemResource(resource);
         }
-        
+
         if (url == null) {
             throw new IOException("Could not find resource " + resource);
         }
-        
+
         return url;
     }
 
diff --git a/src/main/java/com/alibaba/druid/wall/spi/WallVisitorUtils.java b/src/main/java/com/alibaba/druid/wall/spi/WallVisitorUtils.java
index fc25109eef..7236ac488f 100644
--- a/src/main/java/com/alibaba/druid/wall/spi/WallVisitorUtils.java
+++ b/src/main/java/com/alibaba/druid/wall/spi/WallVisitorUtils.java
@@ -414,7 +414,7 @@ public class WallVisitorUtils {
 
         if (x instanceof SQLNotExpr) {
             Object result = getValue(((SQLNotExpr) x).getExpr());
-            if (result != null && result instanceof Boolean) {
+            if (result instanceof Boolean) {
                 return !((Boolean) result).booleanValue();
             }
         }