Package com.remondis.propertypath.api

Interface Get<I,​O,​E extends java.lang.Exception>

  • Type Parameters:
    I - The type to evaluate a property path on.
    O - The type of the property value.
    E - The exception type that may be thrown by the property path.
    All Known Subinterfaces:
    GetAndApply<I,​O,​T,​E>
    All Known Implementing Classes:
    GetAndApplyImpl, GetImpl
    public interface Get<I,​O,​E extends java.lang.Exception>
    This class represents a getter that can be evaluated on a real object instance of a matching type. The getter returns instances of Optional. If the value of the evaluated property path is present, it can be accessed through Optional.get(). If the property path does not have a value, an empty Optional is returned.

    A property path is a chain of get-calls. If a getter returns null the property path does not have a value. The same is true for lists and maps that are either null or do not contain a specified index or key. The null-checks are performed by the library an must not be implemented in the property path.

    Important information

    Once the builder creates a Get instance, this instance can and should be reused. This library creates proxy classes which is a time consuming operation that is only neccessary once. So cache the Get instance as long as possible.

    Implementation hints

    The implementation is expected to provide a valid Object.equals(Object) method. Two getters are considered equal if their types, property paths and the respective argument values are equal. The optional transform function cannot be compared, so this must be excluded from the equals/hashCode computation.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      <X> GetAndApply<I,​O,​X,​E> andApply​(java.util.function.Function<O,​X> mapping)
      Specifies a mapping function that is applied if the getter returned a non-null value.
      java.util.Optional<O> from​(I object)
      Evaluates the property path on the specified object.
      O fromOrDefault​(I object, O defaultValue)
      Evaluates the property path on the specified object.
      java.lang.String toPath()  
      java.lang.String toString​(boolean detailed)  

    • Method Detail

      • from

        java.util.Optional<O> from​(I object)
                    throws E extends java.lang.Exception
        Evaluates the property path on the specified object.
        Parameters:
        object - The object to evaluate the property path on.
        Returns:
        Returns the value of the property wrapped in an Optional.
        Throws:
        E - May be thrown by the property path.
        E extends java.lang.Exception

      • fromOrDefault

        O fromOrDefault​(I object,
                O defaultValue)
         throws E extends java.lang.Exception
        Evaluates the property path on the specified object. If a value is present it will be returned, otherwise the specified default value is returned.
        Parameters:
        object - The object to evaluate the property path on.
        defaultValue - The default value to return in case the property path does not have a value.
        Returns:
        If a value is present it will be returned, otherwise the specified default value is returned.
        Throws:
        E - May be thrown by the property path.
        E extends java.lang.Exception

      • andApply

        <X> GetAndApply<I,​O,​X,​E> andApply​(java.util.function.Function<O,​X> mapping)
        Specifies a mapping function that is applied if the getter returned a non-null value. The mapping function can be used for calculations or type conversions.
        Type Parameters:
        X - The new return type of the getter after applying the mapping function.
        Parameters:
        mapping - The mapping function - only applied if the getter has a non-null return value.
        Returns:
        Returns a new object for further configuration.

      • toString

        java.lang.String toString​(boolean detailed)
        Returns:
        Returns a detailed string if specified, otherwise a shorter string is returned.

      • toPath

        java.lang.String toPath()
        Returns:
        Returns a JSON-like property path. Example: a.b.cs[0].d