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A fast dependency injector for Android and Java.
/*
* Copyright (C) 2016 The Dagger Authors.
*
* 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.
*/
package dagger.internal;
/**
* An adaptation of Guava's {@code com.google.common.base.Preconditions} that is specially tailored
* to support checks applied in Dagger's generated code.
*/
public final class Preconditions {
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference) {
if (reference == null) {
throw new NullPointerException();
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMessage the exception message to use if the check fails
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
*/
public static T checkNotNull(T reference, String errorMessage) {
if (reference == null) {
throw new NullPointerException(errorMessage);
}
return reference;
}
/**
* Ensures that an object reference passed as a parameter to the calling method is not null.
*
* @param reference an object reference
* @param errorMessageTemplate a template for the exception message should the check fail. The
* message is formed by replacing the single {@code %s} placeholder in the template with
* {@code errorMessageArg}.
* @param errorMessageArg the argument to be substituted into the message template. Converted to a
* string using {@link String#valueOf(Object)}, except for {@link Class} objects, which use
* {@link Class#getCanonicalName()}.
* @return the non-null reference that was validated
* @throws NullPointerException if {@code reference} is null
* @throws IllegalArgumentException if {@code errorMessageTemplate} doesn't contain exactly one
* "%s"
*/
public static T checkNotNull(
T reference, String errorMessageTemplate, Object errorMessageArg) {
if (reference == null) {
// Simple implementation of String.format, which is not GWT-compatible
if (!errorMessageTemplate.contains("%s")) {
throw new IllegalArgumentException("errorMessageTemplate has no format specifiers");
}
if (errorMessageTemplate.indexOf("%s") != errorMessageTemplate.lastIndexOf("%s")) {
throw new IllegalArgumentException(
"errorMessageTemplate has more than one format specifier");
}
String argString =
errorMessageArg instanceof Class
? ((Class) errorMessageArg).getCanonicalName()
: String.valueOf(errorMessageArg);
throw new NullPointerException(errorMessageTemplate.replace("%s", argString));
}
return reference;
}
private Preconditions() {}
}