Author: scolebourne
Date: Thu Jul 7 09:52:00 2011
New Revision: 1143735
URL: http://svn.apache.org/viewvc?rev=1143735&view=rev
Log:
Review and cleanup Javadoc in ConstructorUtils
Modified:
commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/reflect/ConstructorUtils.java
Modified:
commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/reflect/ConstructorUtils.java
URL:
http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/reflect/ConstructorUtils.java?rev=1143735&r1=1143734&r2=1143735&view=diff
==============================================================================
---
commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/reflect/ConstructorUtils.java
(original)
+++
commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/reflect/ConstructorUtils.java
Thu Jul 7 09:52:00 2011
@@ -58,33 +58,27 @@ public class ConstructorUtils {
}
/**
- * <p>Returns a new instance of <code>cls</code> created using the actual
- * arguments <code>args</code>. The formal parameter types are inferred
from
- * the actual values of <code>args</code>. See
- * {@link #invokeExactConstructor(Class, Object[], Class[])} for more
- * details.</p>
- *
- * <p>The signatures should be assignment compatible.</p>
- *
- * @param <T> the type to be constructed
- * @param cls the class to be constructed.
- * @param args actual argument array
- * @return new instance of <code>cls</code>
- *
- * @throws NoSuchMethodException If the constructor cannot be found
- * @throws IllegalAccessException If an error occurs accessing the
- * constructor
- * @throws InvocationTargetException If an error occurs invoking the
- * constructor
- * @throws InstantiationException If an error occurs instantiating the
class
- *
- * @see #invokeConstructor(java.lang.Class, java.lang.Object[],
- * java.lang.Class[])
+ * <p>Returns a new instance of the specified class inferring the right
constructor
+ * from the types of the arguments.</p>
+ *
+ * <p>This locates and calls a constructor.
+ * The constructor signature must match the argument types by assignment
compatibility.</p>
+ *
+ * @param <T> the type to be constructed
+ * @param cls the class to be constructed, not null
+ * @param args the array of arguments, null treated as empty
+ * @return new instance of <code>cls</code>, not null
+ *
+ * @throws NoSuchMethodException if a matching constructor cannot be found
+ * @throws IllegalAccessException if invocation is not permitted by
security
+ * @throws InvocationTargetException if an error occurs on invocation
+ * @throws InstantiationException if an error occurs on instantiation
+ * @see #invokeConstructor(java.lang.Class, java.lang.Object[],
java.lang.Class[])
*/
public static <T> T invokeConstructor(Class<T> cls, Object... args)
throws NoSuchMethodException, IllegalAccessException,
InvocationTargetException,
InstantiationException {
- if (null == args) {
+ if (args == null) {
args = ArrayUtils.EMPTY_OBJECT_ARRAY;
}
Class<?> parameterTypes[] = new Class[args.length];
@@ -95,22 +89,22 @@ public class ConstructorUtils {
}
/**
- * <p>Returns a new instance of <code>cls</code> created using constructor
- * with signature <code>parameterTypes</code> and actual arguments
- * <code>args</code>.</p>
- *
- * <p>The signatures should be assignment compatible.</p>
- *
- * @param <T> the type to be constructed
- * @param cls the class to be constructed.
- * @param args actual argument array
- * @param parameterTypes parameter types array
- * @return new instance of <code>cls</code>
- *
- * @throws NoSuchMethodException if matching constructor cannot be found
- * @throws IllegalAccessException thrown on the constructor's invocation
- * @throws InvocationTargetException thrown on the constructor's invocation
- * @throws InstantiationException thrown on the constructor's invocation
+ * <p>Returns a new instance of the specified class choosing the right
constructor
+ * from the list of parameter types.</p>
+ *
+ * <p>This locates and calls a constructor.
+ * The constructor signature must match the parameter types by assignment
compatibility.</p>
+ *
+ * @param <T> the type to be constructed
+ * @param cls the class to be constructed, not null
+ * @param args the array of arguments, null treated as empty
+ * @param parameterTypes the array of parameter types, null treated as
empty
+ * @return new instance of <code>cls</code>, not null
+ *
+ * @throws NoSuchMethodException if a matching constructor cannot be found
+ * @throws IllegalAccessException if invocation is not permitted by
security
+ * @throws InvocationTargetException if an error occurs on invocation
+ * @throws InstantiationException if an error occurs on instantiation
* @see Constructor#newInstance
*/
public static <T> T invokeConstructor(Class<T> cls, Object[] args,
Class<?>[] parameterTypes)
@@ -123,41 +117,35 @@ public class ConstructorUtils {
args = ArrayUtils.EMPTY_OBJECT_ARRAY;
}
Constructor<T> ctor = getMatchingAccessibleConstructor(cls,
parameterTypes);
- if (null == ctor) {
- throw new NoSuchMethodException("No such accessible constructor on
object: "
- + cls.getName());
+ if (ctor == null) {
+ throw new NoSuchMethodException(
+ "No such accessible constructor on object: " + cls.getName());
}
return ctor.newInstance(args);
}
/**
- * <p>Returns a new instance of <code>cls</code> created using the actual
- * arguments <code>args</code>. The formal parameter types are inferred
from
- * the actual values of <code>args</code>. See
- * {@link #invokeExactConstructor(Class, Object[], Class[])} for more
- * details.</p>
+ * <p>Returns a new instance of the specified class inferring the right
constructor
+ * from the types of the arguments.</p>
*
- * <p>The signatures should match exactly.</p>
+ * <p>This locates and calls a constructor.
+ * The constructor signature must match the argument types exactly.</p>
*
* @param <T> the type to be constructed
- * @param cls the class to be constructed.
- * @param args actual argument array
- * @return new instance of <code>cls</code>
- *
- * @throws NoSuchMethodException If the constructor cannot be found
- * @throws IllegalAccessException If an error occurs accessing the
- * constructor
- * @throws InvocationTargetException If an error occurs invoking the
- * constructor
- * @throws InstantiationException If an error occurs instantiating the
class
- *
- * @see #invokeExactConstructor(java.lang.Class, java.lang.Object[],
- * java.lang.Class[])
+ * @param cls the class to be constructed, not null
+ * @param args the array of arguments, null treated as empty
+ * @return new instance of <code>cls</code>, not null
+ *
+ * @throws NoSuchMethodException if a matching constructor cannot be found
+ * @throws IllegalAccessException if invocation is not permitted by
security
+ * @throws InvocationTargetException if an error occurs on invocation
+ * @throws InstantiationException if an error occurs on instantiation
+ * @see #invokeExactConstructor(java.lang.Class, java.lang.Object[],
java.lang.Class[])
*/
public static <T> T invokeExactConstructor(Class<T> cls, Object... args)
throws NoSuchMethodException, IllegalAccessException,
InvocationTargetException,
InstantiationException {
- if (null == args) {
+ if (args == null) {
args = ArrayUtils.EMPTY_OBJECT_ARRAY;
}
int arguments = args.length;
@@ -169,22 +157,22 @@ public class ConstructorUtils {
}
/**
- * <p>Returns a new instance of <code>cls</code> created using constructor
- * with signature <code>parameterTypes</code> and actual arguments
- * <code>args</code>.</p>
+ * <p>Returns a new instance of the specified class choosing the right
constructor
+ * from the list of parameter types.</p>
*
- * <p>The signatures should match exactly.</p>
+ * <p>This locates and calls a constructor.
+ * The constructor signature must match the parameter types exactly.</p>
*
* @param <T> the type to be constructed
- * @param cls the class to be constructed.
- * @param args actual argument array
- * @param parameterTypes parameter types array
- * @return new instance of <code>cls</code>
- *
- * @throws NoSuchMethodException if matching constructor cannot be found
- * @throws IllegalAccessException thrown on the constructor's invocation
- * @throws InvocationTargetException thrown on the constructor's invocation
- * @throws InstantiationException thrown on the constructor's invocation
+ * @param cls the class to be constructed, not null
+ * @param args the array of arguments, null treated as empty
+ * @param parameterTypes the array of parameter types, null treated as
empty
+ * @return new instance of <code>cls</code>, not null
+ *
+ * @throws NoSuchMethodException if a matching constructor cannot be found
+ * @throws IllegalAccessException if invocation is not permitted by
security
+ * @throws InvocationTargetException if an error occurs on invocation
+ * @throws InstantiationException if an error occurs on instantiation
* @see Constructor#newInstance
*/
public static <T> T invokeExactConstructor(Class<T> cls, Object[] args,
@@ -197,20 +185,24 @@ public class ConstructorUtils {
parameterTypes = ArrayUtils.EMPTY_CLASS_ARRAY;
}
Constructor<T> ctor = getAccessibleConstructor(cls, parameterTypes);
- if (null == ctor) {
- throw new NoSuchMethodException("No such accessible constructor on
object: "
- + cls.getName());
+ if (ctor == null) {
+ throw new NoSuchMethodException(
+ "No such accessible constructor on object: "+ cls.getName());
}
return ctor.newInstance(args);
}
+ //-----------------------------------------------------------------------
/**
- * Returns a constructor given a class and signature.
- *
- * @param <T> the type to be constructed
- * @param cls the class to be constructed
- * @param parameterTypes the parameter array
- * @return null if matching accessible constructor can not be found
+ * <p>Finds a constructor given a class and signature, checking
accessibiilty.</p>
+ *
+ * <p>This finds the constructor and ensures that it is accessible.
+ * The constructor signature must match the parameter types exactly.</p>
+ *
+ * @param <T> the constructor type
+ * @param cls the class to find a constructor for, not null
+ * @param parameterTypes the array of parameter types, null treated as
empty
+ * @return the constructor, null if no matching accessible constructor
found
* @see Class#getConstructor
* @see #getAccessibleConstructor(java.lang.reflect.Constructor)
*/
@@ -224,11 +216,13 @@ public class ConstructorUtils {
}
/**
- * Returns accessible version of the given constructor.
- *
- * @param <T> the type to be constructed
- * @param ctor prototype constructor object.
- * @return <code>null</code> if accessible constructor can not be found.
+ * <p>Checks if the specified constructor is accessible.</p>
+ *
+ * <p>This simply ensures that the constructor is accessible.</p>
+ *
+ * @param <T> the constructor type
+ * @param ctor the prototype constructor object, not null
+ * @return the constructor, null if no matching accessible constructor
found
* @see java.lang.SecurityManager
*/
public static <T> Constructor<T> getAccessibleConstructor(Constructor<T>
ctor) {
@@ -237,21 +231,21 @@ public class ConstructorUtils {
}
/**
- * <p>Finds an accessible constructor with compatible parameters.
Compatible
- * parameters mean that every method parameter is assignable from the given
- * parameters. In other words, it finds constructor that will take the
- * parameters given.</p>
- *
- * <p>First it checks if there is constructor matching the exact signature.
- * If no such, all the constructors of the class are tested if their
- * signatures are assignment compatible with the parameter types. The first
- * matching constructor is returned.</p>
+ * <p>Finds an accessible constructor with compatible parameters.</p>
+ *
+ * <p>This checks all the constructor and finds one with compatible
parameters
+ * This requires that every parameter is assignable from the given
parameter types.
+ * This is a more flexible search than the normal exact matching
algorithm.</p>
+ *
+ * <p>First it checks if there is a constructor matching the exact
signature.
+ * If not then all the constructors of the class are checked to see if
their
+ * signatures are assignment compatible with the parameter types.
+ * The first assignment compatible matching constructor is returned.</p>
*
- * @param <T> the type to be constructed
- * @param cls find constructor for this class
+ * @param <T> the constructor type
+ * @param cls the class to find a constructor for, not null
* @param parameterTypes find method with compatible parameters
- * @return a valid Constructor object. If there's no matching constructor,
- * returns <code>null</code>.
+ * @return the constructor, null if no matching accessible constructor
found
*/
public static <T> Constructor<T> getMatchingAccessibleConstructor(Class<T>
cls,
Class<?>... parameterTypes) {
