NotNull.java

/*
 * Copyright 2017 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,
 * 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 com.google.firebase.database.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * An element annotated with this class indicates that it cannot be null. This is used by lint tools
 * to ensure callers properly check for null values before sending values as parameters. It can also
 * be used on return values to indicate to the caller that the return cannot be null so therefore no
 * null checks need to be made.
 */
@Retention(RetentionPolicy.CLASS)
@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE})
public @interface NotNull {

  String value() default "";
}