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Java example source code file (CheckedProviderMethod.java)

This example Java source code file (CheckedProviderMethod.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, assertionerror, checkedprovider, checkedprovidermethod, class, error, exception, immutableset, invocationtargetexception, key, list, object, reflection, secondarybinder, suppresswarnings, throwable, util

The CheckedProviderMethod.java Java example source code

 * Copyright (C) 2008 Google Inc.
 * 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package com.google.inject.throwingproviders;

import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.Exposed;
import com.google.inject.Key;
import com.google.inject.PrivateBinder;
import com.google.inject.Provider;
import com.google.inject.TypeLiteral;
import com.google.inject.binder.ScopedBindingBuilder;
import com.google.inject.internal.util.StackTraceElements;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.HasDependencies;
import com.google.inject.throwingproviders.ThrowingProviderBinder.SecondaryBinder;

import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Set;

 * A provider that invokes a method and returns its result.
 * @author sameb@google.com (Sam Berlin)
class CheckedProviderMethod<T> implements CheckedProvider, HasDependencies {
  private final Key<T> key;
  private final Class<? extends Annotation> scopeAnnotation;
  private final Object instance;
  private final Method method;
  private final ImmutableSet<Dependency dependencies;
  private final List<Provider parameterProviders;
  private final boolean exposed;
  private final Class<? extends CheckedProvider> checkedProvider;
  private final List<TypeLiteral exceptionTypes;
  private final boolean scopeExceptions;

      Key<T> key,
      Method method,
      Object instance,
      ImmutableSet<Dependency dependencies,
      List<Provider parameterProviders,
      Class<? extends Annotation> scopeAnnotation,
      Class<? extends CheckedProvider> checkedProvider,
      List<TypeLiteral exceptionTypes,
      boolean scopeExceptions) {
    this.key = key;
    this.scopeAnnotation = scopeAnnotation;
    this.instance = instance;
    this.dependencies = dependencies;
    this.method = method;
    this.parameterProviders = parameterProviders;
    this.exposed = method.isAnnotationPresent(Exposed.class);
    this.checkedProvider = checkedProvider;
    this.exceptionTypes = exceptionTypes;
    this.scopeExceptions = scopeExceptions;


  void configure(Binder binder) {
    binder = binder.withSource(method);

    SecondaryBinder<?, ?> sbinder = 
          .bind(checkedProvider, key.getTypeLiteral());
    if(key.getAnnotation() != null) {
      sbinder = sbinder.annotatedWith(key.getAnnotation());
    } else if(key.getAnnotationType() != null) {
      sbinder = sbinder.annotatedWith(key.getAnnotationType());
    ScopedBindingBuilder sbbuilder = sbinder.toProviderMethod(this);
    if(scopeAnnotation != null) {

    if (exposed) {
      // the cast is safe 'cause the only binder we have implements PrivateBinder. If there's a
      // misplaced @Exposed, calling this will add an error to the binder's error queue
      ((PrivateBinder) binder).expose(sbinder.getKey());
        binder, exceptionTypes, sbinder.getExceptionTypes(), checkedProvider);

  public T get() throws Exception {
    Object[] parameters = new Object[parameterProviders.size()];
    for (int i = 0; i < parameters.length; i++) {
      parameters[i] = parameterProviders.get(i).get();

    try {
      // We know this cast is safe becase T is the method's return type.
      @SuppressWarnings({ "unchecked", "UnnecessaryLocalVariable" })
      T result = (T) method.invoke(instance, parameters);
      return result;
    } catch (IllegalAccessException e) {
      throw new AssertionError(e);
    } catch (InvocationTargetException e) {
      Throwable t = e.getCause();
      if(t instanceof Exception) {
        throw (Exception)t;
      } else if(t instanceof Error) {
        throw (Error)t;
      } else {
        throw new IllegalStateException(t);

  public Set<Dependency getDependencies() {
    return dependencies;

  @Override public String toString() {
    return "@CheckedProvides " + StackTraceElements.forMember(method);

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