javolution37.javolution.lang

Class Reflection

java.lang.Object

javolution37.javolution.lang.Reflection

public final class Reflection
extends java.lang.Object

This utility class greatly facilitates the use of reflection to invoke constructors or methods which may or may not exist at runtime.

The constructors/methods are identified through their signatures represented as a String. When the constructor/method does not exist (e.g. class not found) or when the platform does not support reflection, the constructor/method is null (no exception raised). Here is an example of timer taking advantage of the new (JRE1.5+) high resolution time when available:

     public static long microTime() {
         if (NANO_TIME_METHOD != null) { // JRE 1.5+
             Long time = (Long) NANO_TIME_METHOD.invoke(null); // Static method.
             return time.longValue() / 1000;
         } else { // Use the less accurate time in milliseconds.
             return System.currentTimeMillis() * 1000;
         }
     }
     private static final Reflection.Method NANO_TIME_METHOD 
         = Reflection.getMethod("java.lang.System.nanoTime()");

Arrays and primitive types are supported. For example:

     Reflection.Constructor sbc = Reflection.getConstructor("java.lang.StringBuilder(int)");
     if (sbc != null) { // JDK 1.5+
        Object sb = sbc.newInstance(new Integer(32));
        Reflection.Method append = Reflection.getMethod("java.lang.StringBuilder.append(char[], int, int)");
        append.invoke(sb, new char[] { 'h', 'i' }, new Integer(0), new Integer(2));
        System.out.println(sb);
    }
 
    > hi

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Reflection.Constructor This class represents a run-time constructor obtained through reflection.
static class	Reflection.Method This class represents a run-time method obtained through reflection.

Method Summary

Modifier and Type	Method and Description
static java.lang.Class	getClass(java.lang.String name) Returns and initializes the class having the specified name (returns null if the class is not found).
static Reflection.Constructor	getConstructor(java.lang.String signature) Returns the constructor having the specified signature.
static Reflection.Method	getMethod(java.lang.String signature) Returns the method having the specified signature.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getClass

public static java.lang.Class getClass(java.lang.String name)

Returns and initializes the class having the specified name (returns null if the class is not found). This method searches the Reflection.class class loader first (which might be the bootstrap class loader), then the context class loader and finally the system class loader.

Parameters:

name - the name of the class to search for.

Returns:

the corresponding class or null if the class is not found or if an error occurs during initialization (in which case a warning or error is logged).

getConstructor

public static Reflection.Constructor getConstructor(java.lang.String signature)

Returns the constructor having the specified signature.

Parameters:

signature - the textual representation of the constructor signature.

Returns:

the corresponding constructor or null if none found.

getMethod

public static Reflection.Method getMethod(java.lang.String signature)

Returns the method having the specified signature.

Parameters:

signature - the textual representation of the method signature.

Returns:

the corresponding constructor or null if none found.