observable/src/com/android/tools/idea/observable/core/ConstantBool.java

/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * 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.android.tools.idea.observable.core;

import com.android.tools.idea.observable.InvalidationListener;
import org.jetbrains.annotations.NotNull;

/**
 * An {@link ObservableBool} with a constant value than never changes.
 */
abstract class ConstantBool implements ObservableBool {
  @Override
  public void addListener(@NotNull InvalidationListener listener) {
    // No need to notify the listener since the value never changes.
  }

  @Override
  public void removeListener(@NotNull InvalidationListener listener) {
    // No need to notify the listener since the value never changes.
  }

  @Override
  public void addWeakListener(@NotNull InvalidationListener listener) {
    // No need to notify the listener since the value never changes.
  }
}