Java Reference
In-Depth Information
Listing 1-5.
A DefaultException Class That Is Inherited from the Throwable Exception Class
// DefaultException.java
package com.jdojo.annotation;
public class DefaultException extends java.lang.Throwable {
public DefaultException() {
}
public DefaultException(String msg) {
super(msg);
}
}
Listing 1-6 shows the code for a
TestCase
annotation type.
Listing 1-6.
A TestCase Annotation Type Whose Instances Are Used to Annotate Test Case Methods
// TestCase.java
package com.jdojo.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface TestCase {
Class<? extends Throwable> willThrow() default DefaultException.class;
}
The return type of the
willThrow
element is defined as the wild card of the
Throwable
class, so that the user will
specify only the
Throwable
class or its subclasses as the element's value. You could have used the
Class
type as the
type of your
willThrow
element. However, that would have allowed the users of this annotation type to pass any class
type as its value. Note that you have used two annotations,
@Retention
and
@Target
, for the
TestCase
annotation
type. The
@Retention
annotation type specified that the
@TestCase
annotation would be available at runtime. It is
necessary to use the retention policy of
RUNTIME
for your
TestCase
annotation type because it is meant for the test
runner tool to read it at runtime. The
@Target
annotation states that the
TestCase
annotation can be used only to
annotate methods. I will cover the
@Retention
and
@Target
annotation types in detail in later sections when I discuss
meta-annotations. Listing 1-7 shows the use of your
TestCase
annotation type.
Listing 1-7.
A Test Case That Uses the TestCase Annotations
// PolicyTestCases.java
package com.jdojo.annotation;
import java.io.IOException;
public class PolicyTestCases {
// Must throw IOExceptionn
@TestCase(willThrow=IOException.class)
public static void testCase1(){
