jdk1.8-ConcurrentHashMap源码

   @Override
    default V getOrDefault(Object key, V defaultValue) {}
    
    @Override
    default void forEach(BiConsumer<? super K, ? super V> action) {}
    
    V putIfAbsent(K key, V value);
    boolean remove(Object key, Object value);
    boolean replace(K key, V oldValue, V newValue);
    V replace(K key, V value);
    
    @Override
    default void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {}
    
    @Override
    default V computeIfAbsent(K key,Function<? super K, ? extends V> mappingFunction) {}
    
    @Override
    default V computeIfPresent(K key,BiFunction<? super K, ? super V, ? extends V> remappingFunction) {}
    
    @Override
    default V compute(K key,BiFunction<? super K, ? super V, ? extends V> remappingFunction) {}
    
    @Override
    default V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {}