Java Method Call invokeNoArgs(Object instance, Method method, Class returnType)

Description

Invokes the method, using the provided instance as 'this', and casts the return value to the provided return type.

License

Apache License

Parameter

Parameter	Description
instance	Instance to use as 'this' for invocation.
method	Method to invoke.
returnType	Return type to cast the method's return value.
T	Return type.

Exception

Parameter	Description

Return

The result of invoking the no-args method, cast to the provided type.

Declaration

public static <T> T invokeNoArgs(Object instance, Method method, Class<T> returnType) 

Method Source Code

//package com.java2s;
/******************************************************************************
 * Copyright (C) 2014 Yevgeny Krasik                                          *
 *                                                                            *
 * Licensed under the Apache License, Version 2.0 (the "License");            *
 * you may not use this file except in compliance with the License.           *
 * You may obtain a copy of the License at                                    *
 *                                                                            *
 * http://www.apache.org/licenses/LICENSE-2.0                                 *
 *                                                                            *
 * Unless required by applicable law or agreed to in writing, software        *
 * distributed under the License is distributed on an "AS IS" BASIS,          *
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   *
 * See the License for the specific language governing permissions and        *
 * limitations under the License.                                             *
 ******************************************************************************/

import java.lang.reflect.Method;

public class Main {
    private static final Object[] NO_ARGS = {};

    /**// w ww .j ava2  s . co  m
     * Invokes the method, using the provided instance as 'this', and casts the return value to the provided return type.
     * Method must be no-args and return the correct type.
     *
     * @param instance Instance to use as 'this' for invocation.
     * @param method Method to invoke.
     * @param returnType Return type to cast the method's return value.
     * @param <T> Return type.
     * @return The result of invoking the no-args method, cast to the provided type.
     * @throws java.lang.IllegalStateException If an error occurred invoking the method.
     */
    public static <T> T invokeNoArgs(Object instance, Method method, Class<T> returnType) {
        try {
            if (!method.isAccessible()) {
                method.setAccessible(true);
            }
            final Object returnValue = method.invoke(instance, NO_ARGS);
            return returnType.cast(returnValue);
        } catch (Exception e) {
            final String message = String.format("Error invoking no-args method: class=%s, method=%s",
                    method.getDeclaringClass(), method.getName());
            throw new IllegalStateException(message, e);
        }
    }
}

Related

1. invokeGetMethodWithSameName(Object object, Method method)
2. invokeHeritedMethod(Object target, String method, Class klass)
3. invokeInstanceMethod(Object target, String methodName, Class type, Object arg)
4. invokeIteratorCallable(String callableClassName, ClassLoader cl)
5. invokeMXMethod(String methodName)
6. invokeNoArgsMethod(Object object, String methodName)
7. invokeNonAccessibleMethod(Class clazz, String methodName, Object instance, Object... params)
8. invokeNonArgMethod(Object object, String methodName)
9. invokeObjectMethod(Object object, String name, Class paramTypes[], Object args[])