implement new Expression methods

org.springframework.expression/src/main/java/org/springframework/expression/common/CompositeStringExpression.java

@@ -11,16 +11,17 @@ import org.springframework.expression.Expression;
  * </pre></code> which will be represented as a CompositeStringExpression of two parts. The first part being a
  * LiteralExpression representing 'Hello ' and the second part being a real expression that will call getName() when
  * invoked.
+ * 
  * @author Andy Clement
  */
 public class CompositeStringExpression implements Expression {
 
-	private String expressionString;
+	private final String expressionString;
 
 	/**
 	 * The array of expressions that make up the composite expression
 	 */
-	private Expression[] expressions;
+	private final Expression[] expressions;
 
 	public CompositeStringExpression(String expressionString, Expression[] expressions) {
 		this.expressionString = expressionString;
@@ -34,7 +35,8 @@ public class CompositeStringExpression implements Expression {
 	public String getValue() throws EvaluationException {
 		StringBuilder sb = new StringBuilder();
 		for (int i = 0; i < expressions.length; i++) {
-			// TODO (asc) is stringify ok for the non literal components? or should the converters be used? see another case below
+			// TODO is stringify ok for the non literal components? or should the converters be used? see another
+			// case below
 			sb.append(expressions[i].getValue());
 		}
 		return sb.toString();
@@ -52,6 +54,10 @@ public class CompositeStringExpression implements Expression {
 		return String.class;
 	}
 
+	public Class getValueType() throws EvaluationException {
+		return String.class;
+	}
+
 	public void setValue(EvaluationContext context, Object value) throws EvaluationException {
 		throw new EvaluationException(expressionString, "Cannot call setValue() on a composite expression");
 	}
@@ -65,4 +71,8 @@ public class CompositeStringExpression implements Expression {
 		Object value = getValue();
 		return ExpressionUtils.convert(null, value, expectedResultType);
 	}
+
+	public boolean isWritable(EvaluationContext context) throws EvaluationException {
+		return false;
+	}
 }

org.springframework.expression/src/main/java/org/springframework/expression/common/LiteralExpression.java

@@ -17,7 +17,7 @@ public class LiteralExpression implements Expression {
 	/**
 	 * Fixed literal value of this expression
 	 */
-	private String literalValue;
+	private final String literalValue;
 
 	public LiteralExpression(String literalValue) {
 		this.literalValue = literalValue;
@@ -40,7 +40,7 @@ public class LiteralExpression implements Expression {
 	}
 
 	public void setValue(EvaluationContext context, Object value) throws EvaluationException {
-		throw new EvaluationException(this.literalValue, "Cannot call setValue() on a LiteralExpression");
+		throw new EvaluationException(literalValue, "Cannot call setValue() on a LiteralExpression");
 	}
 
 	public Object getValue(EvaluationContext context, Class<?> expectedResultType) throws EvaluationException {
@@ -53,4 +53,12 @@ public class LiteralExpression implements Expression {
 		return ExpressionUtils.convert(null, value, expectedResultType);
 	}
 
+	public boolean isWritable(EvaluationContext context) throws EvaluationException {
+		return false;
+	}
+
+	public Class getValueType() throws EvaluationException {
+		return String.class;
+	}
+
 }