Java Reflection Method Invoke invokeMethod(Method method, Object target)

Description

Invoke the specified Method against the supplied target object with no arguments.

License

Apache License

Parameter

Parameter	Description
method	the method to invoke
target	the target object to invoke the method on

Return

the invocation result, if any

Declaration

public static Object invokeMethod(Method method, Object target) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.lang.reflect.*;

public class Main {
    /**//w  w  w  . j a v  a 2  s .  c  om
     * Invoke the specified {@link Method} against the supplied target object with no arguments.
     * The target object can be {@code null} when invoking a static {@link Method}.
     * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.
     *
     * @param method the method to invoke
     * @param target the target object to invoke the method on
     * @return the invocation result, if any
     * @see #invokeMethod(java.lang.reflect.Method, Object, Object[])
     */
    public static Object invokeMethod(Method method, Object target) {
        return invokeMethod(method, target, new Object[0]);
    }

    /**
     * Invoke the specified {@link Method} against the supplied target object with the
     * supplied arguments. The target object can be {@code null} when invoking a
     * static {@link Method}.
     * <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.
     *
     * @param method the method to invoke
     * @param target the target object to invoke the method on
     * @param args   the invocation arguments (may be {@code null})
     * @return the invocation result, if any
     */
    public static Object invokeMethod(Method method, Object target, Object... args) {
        try {
            return method.invoke(target, args);
        } catch (Exception ex) {
            handleReflectionException(ex);
        }
        throw new IllegalStateException("Should never get here");
    }

    /**
     * Handle the given reflection exception. Should only be called if no
     * checked exception is expected to be thrown by the target method.
     * <p>Throws the underlying RuntimeException or Error in case of an
     * InvocationTargetException with such a root cause. Throws an
     * IllegalStateException with an appropriate message else.
     *
     * @param ex the reflection exception to handle
     */
    public static void handleReflectionException(Exception ex) {
        if (ex instanceof NoSuchMethodException) {
            throw new IllegalStateException("Method not found: " + ex.getMessage());
        }
        if (ex instanceof IllegalAccessException) {
            throw new IllegalStateException("Could not access method: " + ex.getMessage());
        }
        if (ex instanceof InvocationTargetException) {
            throw new IllegalStateException("Could not access method: " + ex.getMessage());
        }
        if (ex instanceof RuntimeException) {
            throw (RuntimeException) ex;
        }
        throw new UndeclaredThrowableException(ex);
    }
}

Related

1. invokeMethod(Method method, Object object)
2. invokeMethod(Method method, Object object, Object... args)
3. invokeMethod(Method method, Object object, Object... arguments)
4. invokeMethod(Method method, Object target)
5. invokeMethod(Method method, Object target)
6. invokeMethod(Method method, Object target, Class expectedType)
7. invokeMethod(Method method, Object target, Object... args)
8. invokeMethod(Method method, Object target, Object... args)
9. invokeMethod(Method method, Object target, Object... arguments)