org.apache.commons.lang.builder
Class ReflectionToStringBuilder

java.lang.Object
  |
  +--org.apache.commons.lang.builder.ToStringBuilder
        |
        +--org.apache.commons.lang.builder.ReflectionToStringBuilder

public class ReflectionToStringBuilder

extends ToStringBuilder

Assists in implementing Object.toString() methods using reflection.

This class uses reflection to determine the fields to append. Because these fields are usually private, the class uses AccessibleObject.setAccessible(java.lang.reflect.AccessibleObject[], boolean) to change the visibility of the fields. This will fail under a security manager, unless the appropriate permissions are set up correctly.

A typical invocation for this method would look like:

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

You can also use the builder to debug 3rd party objects:

 System.out.println("An object: " + ReflectionToStringBuilder.toString(anObject));

A subclass can control field output by overriding the methods:

• accept(java.lang.reflect.Field)
• getValue(java.lang.reflect.Field)

For example, this method does not include the password field in the returned String:

 public String toString() {
     return (new ReflectionToStringBuilder(this) {
         protected boolean accept(Field f) {
             return super.accept(f) && !f.getName().equals("password");
         }
     }).toString();
 }

The exact format of the toString is determined by the ToStringStyle passed into the constructor.

Since:

2.0

Version:

$Id: ReflectionToStringBuilder.java,v 1.15 2003/12/02 19:11:58 ggregory Exp $

Author:

Gary Gregory, Stephen Colebourne, Pete Gieser

Constructor Summary

ReflectionToStringBuilder(Object object)
Constructor.

ReflectionToStringBuilder(Object object, ToStringStyle style)
Constructor.

ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer)
Constructor.

ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer, Class reflectUpToClass, boolean outputTransients)
Deprecated. Use ReflectionToStringBuilder(Object,ToStringStyle,StringBuffer,Class,boolean,boolean).

ReflectionToStringBuilder(Object object, ToStringStyle style, StringBuffer buffer, Class reflectUpToClass, boolean outputTransients, boolean outputStatics)
Constructor.

Method Summary

protected boolean	accept(Field field) Returns whether or not to append the given Field.
protected void	appendFieldsIn(Class clazz) Appends the fields and values defined by the given object of the given Class.
Class	getUpToClass() Gets the last super class to stop appending fields for.
protected Object	getValue(Field field) Calls java.lang.reflect.Field.get(Object).
boolean	isAppendStatics() Gets whether or not to append static fields.
boolean	isAppendTransients() Gets whether or not to append transient fields.
ToStringBuilder	reflectionAppendArray(Object array) Append to the toString an Object array.
void	setAppendStatics(boolean appendStatics) Sets whether or not to append static fields.
void	setAppendTransients(boolean appendTransients) Sets whether or not to append transient fields.
void	setUpToClass(Class clazz) Sets the last super class to stop appending fields for.
String	toString() Gets the String built by this builder.
static String	toString(Object object) This method uses reflection to build a suitable toString using the default ToStringStyle.
static String	toString(Object object, ToStringStyle style) This method uses reflection to build a suitable toString.
static String	toString(Object object, ToStringStyle style, boolean outputTransients) This method uses reflection to build a suitable toString.
static String	toString(Object object, ToStringStyle style, boolean outputTransients, boolean outputStatics) This method uses reflection to build a suitable toString.
static String	toString(Object object, ToStringStyle style, boolean outputTransients, boolean outputStatics, Class reflectUpToClass) This method uses reflection to build a suitable toString.
static String	toString(Object object, ToStringStyle style, boolean outputTransients, Class reflectUpToClass) Deprecated. Use toString(Object,ToStringStyle,boolean,boolean,Class)

Methods inherited from class org.apache.commons.lang.builder.ToStringBuilder

append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, append, appendAsObjectToString, appendSuper, appendToString, getDefaultStyle, getObject, getStringBuffer, getStyle, reflectionToString, reflectionToString, reflectionToString, reflectionToString, setDefaultStyle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ReflectionToStringBuilder

public ReflectionToStringBuilder(Object object)

Constructor.

This constructor outputs using the default style set with setDefaultStyle.

Parameters:

object - the Object to build a toString for, must not be null

Throws:

IllegalArgumentException - if the Object passed in is null

ReflectionToStringBuilder

public ReflectionToStringBuilder(Object object,
                                 ToStringStyle style)

Constructor.

If the style is null, the default style is used.

Parameters:

object - the Object to build a toString for, must not be null

style - the style of the toString to create, may be null

Throws:

IllegalArgumentException - if the Object passed in is null

ReflectionToStringBuilder

public ReflectionToStringBuilder(Object object,
                                 ToStringStyle style,
                                 StringBuffer buffer)

Constructor.

If the style is null, the default style is used.

If the buffer is null, a new one is created.

Parameters:

object - the Object to build a toString for

style - the style of the toString to create, may be null

buffer - the StringBuffer to populate, may be null

Throws:

IllegalArgumentException - if the Object passed in is null

ReflectionToStringBuilder

public ReflectionToStringBuilder(Object object,
                                 ToStringStyle style,
                                 StringBuffer buffer,
                                 Class reflectUpToClass,
                                 boolean outputTransients)

Deprecated. Use ReflectionToStringBuilder(Object,ToStringStyle,StringBuffer,Class,boolean,boolean).

Constructor.

Parameters:

object - the Object to build a toString for

style - the style of the toString to create, may be null

buffer - the StringBuffer to populate, may be null

reflectUpToClass - the superclass to reflect up to (inclusive), may be null

outputTransients - whether to include transient fields

ReflectionToStringBuilder

public ReflectionToStringBuilder(Object object,
                                 ToStringStyle style,
                                 StringBuffer buffer,
                                 Class reflectUpToClass,
                                 boolean outputTransients,
                                 boolean outputStatics)

Constructor.

Parameters:

object - the Object to build a toString for

style - the style of the toString to create, may be null

buffer - the StringBuffer to populate, may be null

reflectUpToClass - the superclass to reflect up to (inclusive), may be null

outputTransients - whether to include transient fields

outputStatics - whether to include static fields

Since:

2.1

Method Detail

toString

public static String toString(Object object)

This method uses reflection to build a suitable toString using the default ToStringStyle.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

Transient members will be not be included, as they are likely derived. Static fields will not be included. Superclass fields will be appended.

Parameters:

object - the Object to be output

Returns:

the String result

Throws:

IllegalArgumentException - if the Object is null

toString

public static String toString(Object object,
                              ToStringStyle style)

This method uses reflection to build a suitable toString.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

Transient members will be not be included, as they are likely derived. Static fields will not be included. Superclass fields will be appended.

If the style is null, the default ToStringStyle is used.

Parameters:

object - the Object to be output

style - the style of the toString to create, may be null

Returns:

the String result

Throws:

IllegalArgumentException - if the Object or ToStringStyle is null

toString

public static String toString(Object object,
                              ToStringStyle style,
                              boolean outputTransients)

This method uses reflection to build a suitable toString.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

If the outputTransients is true, transient members will be output, otherwise they are ignored, as they are likely derived fields, and not part of the value of the Object.

Static fields will not be included. Superclass fields will be appended.

If the style is null, the default ToStringStyle is used.

Parameters:

object - the Object to be output

style - the style of the toString to create, may be null

outputTransients - whether to include transient fields

Returns:

the String result

Throws:

IllegalArgumentException - if the Object is null

toString

public static String toString(Object object,
                              ToStringStyle style,
                              boolean outputTransients,
                              boolean outputStatics)

This method uses reflection to build a suitable toString.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

If the outputTransients is true, transient fields will be output, otherwise they are ignored, as they are likely derived fields, and not part of the value of the Object.

If the outputStatics is true, static fields will be output, otherwise they are ignored.

Static fields will not be included. Superclass fields will be appended.

If the style is null, the default ToStringStyle is used.

Parameters:

object - the Object to be output

style - the style of the toString to create, may be null

outputTransients - whether to include transient fields

outputStatics - whether to include transient fields

Returns:

the String result

Throws:

IllegalArgumentException - if the Object is null

Since:

2.1

toString

public static String toString(Object object,
                              ToStringStyle style,
                              boolean outputTransients,
                              boolean outputStatics,
                              Class reflectUpToClass)

This method uses reflection to build a suitable toString.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

If the outputTransients is true, transient fields will be output, otherwise they are ignored, as they are likely derived fields, and not part of the value of the Object.

If the outputStatics is true, static fields will be output, otherwise they are ignored.

Superclass fields will be appended up to and including the specified superclass. A null superclass is treated as java.lang.Object.

If the style is null, the default ToStringStyle is used.

Parameters:

object - the Object to be output

style - the style of the toString to create, may be null

outputTransients - whether to include transient fields

outputStatics - whether to include static fields

reflectUpToClass - the superclass to reflect up to (inclusive), may be null

Returns:

the String result

Throws:

IllegalArgumentException - if the Object is null

Since:

2.1

toString

public static String toString(Object object,
                              ToStringStyle style,
                              boolean outputTransients,
                              Class reflectUpToClass)

Deprecated. Use toString(Object,ToStringStyle,boolean,boolean,Class)

This method uses reflection to build a suitable toString.

It uses AccessibleObject.setAccessible to gain access to private fields. This means that it will throw a security exception if run under a security manager, if the permissions are not set up correctly. It is also not as efficient as testing explicitly.

If the outputTransients is true, transient members will be output, otherwise they are ignored, as they are likely derived fields, and not part of the value of the Object.

Static fields will not be included. Superclass fields will be appended up to and including the specified superclass. A null superclass is treated as java.lang.Object.

If the style is null, the default ToStringStyle is used.

Parameters:

object - the Object to be output

style - the style of the toString to create, may be null

outputTransients - whether to include transient fields

reflectUpToClass - the superclass to reflect up to (inclusive), may be null

Returns:

the String result

Throws:

IllegalArgumentException - if the Object is null

Since:

2.0

accept

protected boolean accept(Field field)

Returns whether or not to append the given Field.

• Transient fields are appended only if isAppendTransients() returns true.
• Static fields are appended only if isAppendStatics() returns true.
• Inner class fields are not appened.

Parameters:

field - The Field to test.

Returns:

Whether or not to append the given Field.

appendFieldsIn

protected void appendFieldsIn(Class clazz)

Appends the fields and values defined by the given object of the given Class.

If a cycle is detected as an object is "toString()'ed", such an object is rendered as if Object.toString() had been called and not implemented by the object.

Parameters:

clazz - The class of object parameter

getUpToClass

public Class getUpToClass()

Gets the last super class to stop appending fields for.

Returns:

The last super class to stop appending fields for.

getValue

protected Object getValue(Field field)
                   throws IllegalArgumentException,
                          IllegalAccessException

Calls java.lang.reflect.Field.get(Object).

Parameters:

field - The Field to query.

Returns:

The Object from the given Field.

Throws:

IllegalArgumentException - see Field.get(Object)

IllegalAccessException - see Field.get(Object)

See Also:

Field.get(Object)

isAppendStatics

public boolean isAppendStatics()

Gets whether or not to append static fields.

Returns:

Whether or not to append static fields.

Since:

2.1

isAppendTransients

public boolean isAppendTransients()

Gets whether or not to append transient fields.

Returns:

Whether or not to append transient fields.

reflectionAppendArray

public ToStringBuilder reflectionAppendArray(Object array)

Append to the toString an Object array.

Parameters:

array - the array to add to the toString

Returns:

this

setAppendStatics

public void setAppendStatics(boolean appendStatics)

Sets whether or not to append static fields.

Parameters:

appendStatics - Whether or not to append static fields.

Since:

2.1

setAppendTransients

public void setAppendTransients(boolean appendTransients)

Sets whether or not to append transient fields.

Parameters:

appendTransients - Whether or not to append transient fields.

setUpToClass

public void setUpToClass(Class clazz)

Sets the last super class to stop appending fields for.

Parameters:

clazz - The last super class to stop appending fields for.

toString

public String toString()

Gets the String built by this builder.

Overrides:

toString in class ToStringBuilder

Returns:

the built string