Package org.apache.commons.lang3.builder

Class ReflectionDiffBuilder<T>

  • Type Parameters:
    T - type of the left and right object to diff.
    All Implemented Interfaces:
    Builder<DiffResult<T>>
    public class ReflectionDiffBuilder<T>
extends java.lang.Object
implements Builder<DiffResult<T>>
    Assists in implementing Diffable.diff(Object) methods.

    All non-static, non-transient fields (including inherited fields) of the objects to diff are discovered using reflection and compared for differences.

    To use this class, write code as follows: 

    
 public class Person implements Diffable<Person> {
   String name;
   int age;
   boolean smoker;
   ...

   public DiffResult<Person> diff(Person obj) {
     // No need for null check, as NullPointerException correct if obj is null
     return ReflectionDiffBuilder.<Person>builder()
       .setDiffBuilder(DiffBuilder.<Person>builder()
           .setLeft(this)
           .setRight(obj)
           .setStyle(ToStringStyle.SHORT_PREFIX_STYLE)
           .build())
       .setExcludeFieldNames("userName", "password")
       .build()  // -> ReflectionDiffBuilder
       .build(); // -> DiffResult
   }
 }

    The ToStringStyle passed to the constructor is embedded in the returned DiffResult and influences the style of the DiffResult.toString() method. This style choice can be overridden by calling DiffResult.toString(ToStringStyle).

    See DiffBuilder for a non-reflection based version of this class.

    Since:
    3.6
    See Also:
    Diffable, Diff, DiffResult, ToStringStyle, DiffBuilder

    • Field Detail

      • excludeFieldNames

        private java.lang.String[] excludeFieldNames
        Field names to exclude from output. Intended for fields like "password" or "lastModificationDate".

    • Constructor Detail

      • ReflectionDiffBuilder

        private ReflectionDiffBuilder​(DiffBuilder<T> diffBuilder,
                              java.lang.String[] excludeFieldNames)

      • ReflectionDiffBuilder

        @Deprecated
public ReflectionDiffBuilder​(T left,
                             T right,
                             ToStringStyle style)
        Deprecated.
        Use ReflectionDiffBuilder.Builder.
        Constructs a builder for the specified objects with the specified style.

        If left == right or left.equals(right) then the builder will not evaluate any calls to append(...) and will return an empty DiffResult when build() is executed.

        Parameters:
        left - this object.
        right - the object to diff against.
        style - the style will use when outputting the objects, null uses the default
        Throws:
        java.lang.IllegalArgumentException - if left or right is null.

    • Method Detail

      • toExcludeFieldNames

        private static java.lang.String[] toExcludeFieldNames​(java.lang.String[] excludeFieldNames)

      • accept

        private boolean accept​(java.lang.reflect.Field field)

      • appendFields

        private void appendFields​(java.lang.Class<?> clazz)
        Appends fields using reflection.
        Throws:
        java.lang.SecurityException - if an underlying accessible object's method denies the request.
        See Also:
        SecurityManager.checkPermission(java.security.Permission)

      • build

        public DiffResult<T> build()
        Returns a reference to the object being constructed or result being calculated by the builder.
        Specified by:
        build in interface Builder<T>
        Returns:
        the object constructed or result calculated by the builder.
        Throws:
        java.lang.SecurityException - if an underlying accessible object's method denies the request.
        See Also:
        SecurityManager.checkPermission(java.security.Permission)

      • getExcludeFieldNames

        public java.lang.String[] getExcludeFieldNames()
        Gets the field names that should be excluded from the diff.
        Returns:
        the excludeFieldNames.
        Since:
        3.13.0

      • getLeft

        private T getLeft()

      • getRight

        private T getRight()

      • readField

        private java.lang.Object readField​(java.lang.reflect.Field field,
                                   java.lang.Object target)
                            throws java.lang.IllegalAccessException
        Reads a Field, forcing access if needed.
        Parameters:
        field - the field to use
        target - the object to call on, may be null for static fields
        Returns:
        the field value
        Throws:
        java.lang.NullPointerException - if the field is null
        java.lang.IllegalAccessException - if the field is not made accessible
        java.lang.SecurityException - if an underlying accessible object's method denies the request.
        See Also:
        SecurityManager.checkPermission(java.security.Permission)