Remove hardcoded strings

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/common/AbstractBooleanExpressionDSL.java

@@ -145,9 +145,9 @@ private void addSubCriteria(String connector, List<AndOrCriteriaGroup> criteria)
                 .build());
     }
 
-    protected void setInitialCriterion(SqlCriterion initialCriterion, String errorMessage) {
+    protected void setInitialCriterion(SqlCriterion initialCriterion, StatementType statementType) {
         if (this.initialCriterion != null) {
-            throw new InvalidSqlException(Messages.getString(errorMessage)); //$NON-NLS-1$
+            throw new InvalidSqlException(Messages.getString(statementType.messageNumber())); //$NON-NLS-1$
         }
 
         this.initialCriterion = initialCriterion;
@@ -159,4 +159,19 @@ protected SqlCriterion getInitialCriterion() {
     }
 
     protected abstract T getThis();
+
+    public enum StatementType {
+        WHERE("ERROR.32"), //$NON-NLS-1$
+        HAVING("ERROR.31"); //$NON-NLS-1$
+
+        private final String messageNumber;
+
+        public String messageNumber() {
+            return messageNumber;
+        }
+
+        StatementType(String messageNumber) {
+            this.messageNumber = messageNumber;
+        }
+    }
 }

src/main/java/org/mybatis/dynamic/sql/select/AbstractHavingFinisher.java

@@ -21,7 +21,7 @@
 public abstract class AbstractHavingFinisher<T extends AbstractHavingFinisher<T>>
         extends AbstractBooleanExpressionDSL<T> {
     void initialize(SqlCriterion sqlCriterion) {
-        setInitialCriterion(sqlCriterion, "ERROR.31"); //$NON-NLS-1$
+        setInitialCriterion(sqlCriterion, StatementType.HAVING);
     }
 
     protected HavingModel buildModel() {

src/main/java/org/mybatis/dynamic/sql/where/AbstractWhereFinisher.java

@@ -28,7 +28,7 @@ public abstract class AbstractWhereFinisher<T extends AbstractWhereFinisher<T>>
     private final StatementConfiguration statementConfiguration;
 
     void initialize(SqlCriterion sqlCriterion) {
-        setInitialCriterion(sqlCriterion, "ERROR.32"); //$NON-NLS-1$
+        setInitialCriterion(sqlCriterion, StatementType.WHERE);
     }
 
     protected AbstractWhereFinisher(StatementConfiguration statementConfiguration) {