RecursiveToStringStyle

public class org.apache.commons.lang3.builder.RecursiveToStringStyle extends ToStringStyle

Works with ToStringBuilder to create a “deep” toString.

To use this class write code as follows:

public class Job {
  String title;
  ...
}

public class Person {
  String name;
  int age;
  boolean smoker;
  Job job;

  ...

  public String toString() {
    return new ReflectionToStringBuilder(this, new RecursiveToStringStyle()).toString();
  }
}

This will produce a toString of the format: Person@7f54[name=Stephen,age=29,smoker=false,job=Job@43cd2[title=Manager]]

Graph safety: within one top-level toString() call, each object is rendered in detail at most once. A second (identity-equal) occurrence of an object (whether through a true cycle or through a shared (acyclic) reference) is rendered in the abbreviated Object.toString() format instead of being re-traversed. This keeps traversal cost linear in the size of the object graph; without it, shared references (reference “diamonds”) would be re-traversed exponentially. An optional output-length limit can be set via RecursiveToStringStyle.Builder#setMaxOutputLength(int); once the produced string reaches the limit, further nested objects are replaced by a "...<truncated>" marker.

Since:

3.2

Constructors

RecursiveToStringStyle()	Constructs a new instance with no output-length limit.
RecursiveToStringStyle(int)	Constructs a new instance with an output-length limit.

public RecursiveToStringStyle()

Constructs a new instance with no output-length limit.

public RecursiveToStringStyle(int maxOutputLength)

Constructs a new instance with an output-length limit.

Parameters:

maxOutputLength – once the produced string reaches this length, further nested objects are replaced by a "...<truncated>" marker; 0 means unlimited.

Since:

3.21.0

Methods

accept(Class)	Tests whether or not to recursively format the given Class.
appendDetail(StringBuffer, String, Object)	Appends to the toString an Object value, printing the full detail of the Object.
appendDetail(StringBuffer, String, Collection)	Appends to the toString a Collection.
appendInternal(StringBuffer, String, Object, boolean)	Appends to the toString an Object, correctly interpreting its type.
builder()	Creates a new Builder for RecursiveToStringStyle instances.

protected boolean accept(Class<?> clazz)

Tests whether or not to recursively format the given Class.

By default, this method always filters out the following:

• Boxed primitives, see ClassUtils#isPrimitiveWrapper(Class)

• String

• Number subclasses

• AtomicBoolean

• MutableBoolean

Parameters:

clazz – The class to test.

Returns:

Whether or not to recursively format instances of the given Class.

@Override public void appendDetail(StringBuffer buffer, String fieldName, Object value)

Appends to the toString an Object value, printing the full detail of the Object.

Parameters:

• buffer – The StringBuffer to populate.

• fieldName – The field name, typically not used as already appended.

• value – The value to add to the toString, not null.

@Override protected void appendDetail(StringBuffer buffer, String fieldName, Collection<?> coll)

Appends to the toString a Collection.

Parameters:

• buffer – The StringBuffer to populate.

• fieldName – The field name, typically not used as already appended.

• coll – The Collection to add to the toString, not null.

@Override protected void appendInternal(StringBuffer buffer, String fieldName, Object value, boolean detail)

Appends to the toString an Object, correctly interpreting its type.

This method performs the main lookup by Class type to correctly route arrays, Collections, Maps and Objects to the appropriate method.

Either detail or summary views can be specified.

If a cycle is detected, an object will be appended with the Object.toString() format.

In addition to the cycle check performed by the superclass, this implementation keeps a per-thread set of objects already rendered in detail during the current top-level call. Values that this style would traverse structurally (see #accept(Class)) are rendered in detail at most once; later identity-equal occurrences are appended in the abbreviated Object.toString() format. This bounds the traversal to one visit per object, so shared (acyclic) references cannot cause exponential re-traversal. If an output-length limit was configured and the buffer has reached it, a "...<truncated>" marker is appended instead of the value.

Parameters:

• buffer – The StringBuffer to populate.

• fieldName – The field name, typically not used as already appended.

• value – The value to add to the toString, not null.

• detail – output detail or not.

public static RecursiveToStringStyle.Builder builder()

Creates a new Builder for RecursiveToStringStyle instances.

Returns:

a new Builder for RecursiveToStringStyle instances.