Statementpublic class Statement extends Object A Statement object represents a primitive statement
in which a single method is applied to a target and
a set of arguments - as in "a.setFoo(b)".
Note that where this example uses names
to denote the target and its argument, a statement
object does not require a name space and is constructed with
the values themselves.
The statement object associates the named method
with its environment as a simple set of values:
the target and an array of argument values. |
| Fields Summary |
|---|
| private static Object[] | emptyArray | | static ExceptionListener | defaultExceptionListener | | Object | target | | String | methodName | | Object[] | arguments |
| Constructors Summary |
|---|
public Statement(Object target, String methodName, Object[] arguments)Creates a new Statement object with a target,
methodName and arguments as per the parameters.
this.target = target;
this.methodName = methodName;
this.arguments = (arguments == null) ? emptyArray : arguments;
|
| Methods Summary |
|---|
| public void | execute()The execute method finds a method whose name is the same
as the methodName property, and invokes the method on
the target.
When the target's class defines many methods with the given name
the implementation should choose the most specific method using
the algorithm specified in the Java Language Specification
(15.11). The dynamic class of the target and arguments are used
in place of the compile-time type information and, like the
java.lang.reflect.Method class itself, conversion between
primitive values and their associated wrapper classes is handled
internally.
The following method types are handled as special cases:
-
Static methods may be called by using a class object as the target.
-
The reserved method name "new" may be used to call a class's constructor
as if all classes defined static "new" methods. Constructor invocations
are typically considered
Expressions rather than Statements
as they return a value.
-
The method names "get" and "set" defined in the
java.util.List
interface may also be applied to array instances, mapping to
the static methods of the same name in the Array class.
invoke();
| | public java.lang.Object[] | getArguments()Returns the arguments of this statement.
return arguments;
| | public java.lang.String | getMethodName()Returns the name of the method.
return methodName;
| | public java.lang.Object | getTarget()Returns the target of this statement.
return target;
| | java.lang.String | instanceName(java.lang.Object instance)
if (instance == null) {
return "null";
} else if (instance.getClass() == String.class) {
return "\""+(String)instance + "\"";
} else {
// Note: there is a minor problem with using the non-caching
// NameGenerator method. The return value will not have
// specific information about the inner class name. For example,
// In 1.4.2 an inner class would be represented as JList$1 now
// would be named Class.
return NameGenerator.unqualifiedClassName(instance.getClass());
}
| | java.lang.Object | invoke()
Object target = getTarget();
String methodName = getMethodName();
if (target == null || methodName == null) {
throw new NullPointerException((target == null ? "target" :
"methodName") + " should not be null");
}
Object[] arguments = getArguments();
// Class.forName() won't load classes outside
// of core from a class inside core. Special
// case this method.
if (target == Class.class && methodName.equals("forName")) {
return ObjectHandler.classForName((String)arguments[0]);
}
Class[] argClasses = new Class[arguments.length];
for(int i = 0; i < arguments.length; i++) {
argClasses[i] = (arguments[i] == null) ? null : arguments[i].getClass();
}
AccessibleObject m = null;
if (target instanceof Class) {
/*
For class methods, simluate the effect of a meta class
by taking the union of the static methods of the
actual class, with the instance methods of "Class.class"
and the overloaded "newInstance" methods defined by the
constructors.
This way "System.class", for example, will perform both
the static method getProperties() and the instance method
getSuperclass() defined in "Class.class".
*/
if (methodName.equals("new")) {
methodName = "newInstance";
}
// Provide a short form for array instantiation by faking an nary-constructor.
if (methodName.equals("newInstance") && ((Class)target).isArray()) {
Object result = Array.newInstance(((Class)target).getComponentType(), arguments.length);
for(int i = 0; i < arguments.length; i++) {
Array.set(result, i, arguments[i]);
}
return result;
}
if (methodName.equals("newInstance") && arguments.length != 0) {
// The Character class, as of 1.4, does not have a constructor
// which takes a String. All of the other "wrapper" classes
// for Java's primitive types have a String constructor so we
// fake such a constructor here so that this special case can be
// ignored elsewhere.
if (target == Character.class && arguments.length == 1 &&
argClasses[0] == String.class) {
return new Character(((String)arguments[0]).charAt(0));
}
m = ReflectionUtils.getConstructor((Class)target, argClasses);
}
if (m == null && target != Class.class) {
m = ReflectionUtils.getMethod((Class)target, methodName, argClasses);
}
if (m == null) {
m = ReflectionUtils.getMethod(Class.class, methodName, argClasses);
}
}
else {
/*
This special casing of arrays is not necessary, but makes files
involving arrays much shorter and simplifies the archiving infrastrcure.
The Array.set() method introduces an unusual idea - that of a static method
changing the state of an instance. Normally statements with side
effects on objects are instance methods of the objects themselves
and we reinstate this rule (perhaps temporarily) by special-casing arrays.
*/
if (target.getClass().isArray() &&
(methodName.equals("set") || methodName.equals("get"))) {
int index = ((Integer)arguments[0]).intValue();
if (methodName.equals("get")) {
return Array.get(target, index);
}
else {
Array.set(target, index, arguments[1]);
return null;
}
}
m = ReflectionUtils.getMethod(target.getClass(), methodName, argClasses);
}
if (m != null) {
try {
if (m instanceof Method) {
return MethodUtil.invoke((Method)m, target, arguments);
}
else {
return ((Constructor)m).newInstance(arguments);
}
}
catch (IllegalAccessException iae) {
throw new Exception("Statement cannot invoke: " +
methodName + " on " + target.getClass(),
iae);
}
catch (InvocationTargetException ite) {
Throwable te = ite.getTargetException();
if (te instanceof Exception) {
throw (Exception)te;
}
else {
throw ite;
}
}
}
throw new NoSuchMethodException(toString());
| | public java.lang.String | toString()Prints the value of this statement using a Java-style syntax.
// Respect a subclass's implementation here.
Object target = getTarget();
String methodName = getMethodName();
Object[] arguments = getArguments();
StringBuffer result = new StringBuffer(instanceName(target) + "." + methodName + "(");
int n = arguments.length;
for(int i = 0; i < n; i++) {
result.append(instanceName(arguments[i]));
if (i != n -1) {
result.append(", ");
}
}
result.append(");");
return result.toString();
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