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Java example source code file (ToStringBuilder.java)

This example Java source code file (ToStringBuilder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

class, illegalargumentexception, object, override, string, stringbuffer, the, tostringbuilder, tostringstyle

The ToStringBuilder.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3.builder;

import org.apache.commons.lang3.ObjectUtils;

/**
 * <p>Assists in implementing {@link Object#toString()} methods.

* * <p>This class enables a good and consistent toString() to be built for any * class or object. This class aims to simplify the process by:</p> * <ul> * <li>allowing field names * <li>handling all types consistently * <li>handling nulls consistently * <li>outputting arrays and multi-dimensional arrays * <li>enabling the detail level to be controlled for Objects and Collections * <li>handling class hierarchies * </ul> * * <p>To use this class write code as follows:

* * <pre> * public class Person { * String name; * int age; * boolean smoker; * * ... * * public String toString() { * return new ToStringBuilder(this). * append("name", name). * append("age", age). * append("smoker", smoker). * toString(); * } * } * </pre> * * <p>This will produce a toString of the format: * <code>Person@7f54[name=Stephen,age=29,smoker=false]

* * <p>To add the superclass toString, use {@link #appendSuper}. * To append the <code>toString from an object that is delegated * to (or any other object), use {@link #appendToString}.</p> * * <p>Alternatively, there is a method that uses reflection to determine * the fields to test. Because these fields are usually private, the method, * <code>reflectionToString, uses AccessibleObject.setAccessible to * change the visibility of the fields. This will fail under a security manager, * unless the appropriate permissions are set up correctly. It is also * slower than testing explicitly.</p> * * <p>A typical invocation for this method would look like:

* * <pre> * public String toString() { * return ToStringBuilder.reflectionToString(this); * } * </pre> * * <p>You can also use the builder to debug 3rd party objects:

* * <pre> * System.out.println("An object: " + ToStringBuilder.reflectionToString(anObject)); * </pre> * * <p>The exact format of the toString is determined by * the {@link ToStringStyle} passed into the constructor.</p> * * @since 1.0 */ public class ToStringBuilder implements Builder<String> { /** * The default style of output to use, not null. */ private static volatile ToStringStyle defaultStyle = ToStringStyle.DEFAULT_STYLE; //---------------------------------------------------------------------------- /** * <p>Gets the default ToStringStyle to use.

* * <p>This method gets a singleton default value, typically for the whole JVM. * Changing this default should generally only be done during application startup. * It is recommended to pass a <code>ToStringStyle to the constructor instead * of using this global default.</p> * * <p>This method can be used from multiple threads. * Internally, a <code>volatile variable is used to provide the guarantee * that the latest value set using {@link #setDefaultStyle} is the value returned. * It is strongly recommended that the default style is only changed during application startup.</p> * * <p>One reason for changing the default could be to have a verbose style during * development and a compact style in production.</p> * * @return the default <code>ToStringStyle, never null */ public static ToStringStyle getDefaultStyle() { return defaultStyle; } /** * <p>Sets the default ToStringStyle to use.

* * <p>This method sets a singleton default value, typically for the whole JVM. * Changing this default should generally only be done during application startup. * It is recommended to pass a <code>ToStringStyle to the constructor instead * of changing this global default.</p> * * <p>This method is not intended for use from multiple threads. * Internally, a <code>volatile variable is used to provide the guarantee * that the latest value set is the value returned from {@link #getDefaultStyle}.</p> * * @param style the default <code>ToStringStyle * @throws IllegalArgumentException if the style is <code>null */ public static void setDefaultStyle(final ToStringStyle style) { if (style == null) { throw new IllegalArgumentException("The style must not be null"); } defaultStyle = style; } //---------------------------------------------------------------------------- /** * <p>Uses ReflectionToStringBuilder to generate a * <code>toString for the specified object.

* * @param object the Object to be output * @return the String result * @see ReflectionToStringBuilder#toString(Object) */ public static String reflectionToString(final Object object) { return ReflectionToStringBuilder.toString(object); } /** * <p>Uses ReflectionToStringBuilder to generate a * <code>toString for the specified object.

* * @param object the Object to be output * @param style the style of the <code>toString to create, may be null * @return the String result * @see ReflectionToStringBuilder#toString(Object,ToStringStyle) */ public static String reflectionToString(final Object object, final ToStringStyle style) { return ReflectionToStringBuilder.toString(object, style); } /** * <p>Uses ReflectionToStringBuilder to generate a * <code>toString for the specified object.

* * @param object the Object to be output * @param style the style of the <code>toString to create, may be null * @param outputTransients whether to include transient fields * @return the String result * @see ReflectionToStringBuilder#toString(Object,ToStringStyle,boolean) */ public static String reflectionToString(final Object object, final ToStringStyle style, final boolean outputTransients) { return ReflectionToStringBuilder.toString(object, style, outputTransients, false, null); } /** * <p>Uses ReflectionToStringBuilder to generate a * <code>toString for the specified object.

* * @param <T> the type of the object * @param object the Object to be output * @param style the style of the <code>toString to create, may be null * @param outputTransients whether to include transient fields * @param reflectUpToClass the superclass to reflect up to (inclusive), may be <code>null * @return the String result * @see ReflectionToStringBuilder#toString(Object,ToStringStyle,boolean,boolean,Class) * @since 2.0 */ public static <T> String reflectionToString( final T object, final ToStringStyle style, final boolean outputTransients, final Class<? super T> reflectUpToClass) { return ReflectionToStringBuilder.toString(object, style, outputTransients, false, reflectUpToClass); } //---------------------------------------------------------------------------- /** * Current toString buffer, not null. */ private final StringBuffer buffer; /** * The object being output, may be null. */ private final Object object; /** * The style of output to use, not null. */ private final ToStringStyle style; /** * <p>Constructs a builder for the specified object using the default output style.

* * <p>This default style is obtained from {@link #getDefaultStyle()}.

* * @param object the Object to build a <code>toString for, not recommended to be null */ public ToStringBuilder(final Object object) { this(object, null, null); } /** * <p>Constructs a builder for the specified object using the a defined output style.

* * <p>If the style is null, the default style is used.

* * @param object the Object to build a <code>toString for, not recommended to be null * @param style the style of the <code>toString to create, null uses the default style */ public ToStringBuilder(final Object object, final ToStringStyle style) { this(object, style, null); } /** * <p>Constructs a builder for the specified object.

* * <p>If the style is null, the default style is used.

* * <p>If the buffer is null, a new one is created.

* * @param object the Object to build a <code>toString for, not recommended to be null * @param style the style of the <code>toString to create, null uses the default style * @param buffer the <code>StringBuffer to populate, may be null */ public ToStringBuilder(final Object object, ToStringStyle style, StringBuffer buffer) { if (style == null) { style = getDefaultStyle(); } if (buffer == null) { buffer = new StringBuffer(512); } this.buffer = buffer; this.style = style; this.object = object; style.appendStart(buffer, object); } //---------------------------------------------------------------------------- /** * <p>Append to the toString a boolean * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final boolean value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a boolean * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final boolean[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a byte * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final byte value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a byte * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final byte[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a char * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final char value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a char * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final char[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a double * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final double value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a double * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final double[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a float * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final float value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a float * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final float[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString an int * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final int value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString an int * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final int[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a long * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final long value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a long * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final long[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString an Object * value.</p> * * @param obj the value to add to the <code>toString * @return this */ public ToStringBuilder append(final Object obj) { style.append(buffer, null, obj, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString an Object * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final Object[] array) { style.append(buffer, null, array, null); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a short * value.</p> * * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final short value) { style.append(buffer, null, value); return this; } //---------------------------------------------------------------------------- /** * <p>Append to the toString a short * array.</p> * * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final short[] array) { style.append(buffer, null, array, null); return this; } /** * <p>Append to the toString a boolean * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final boolean value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a boolean * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>hashCode * @return this */ public ToStringBuilder append(final String fieldName, final boolean[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a boolean * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final boolean[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an byte * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final byte value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a byte array.

* * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final byte[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a byte * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array. * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final byte[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString a char * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final char value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a char * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final char[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a char * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final char[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString a double * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final double value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a double * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final double[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a double * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final double[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an float * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final float value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a float * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final float[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a float * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final float[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an int * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final int value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString an int * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final int[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString an int * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final int[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString a long * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final long value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a long * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final long[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a long * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final long[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an Object * value.</p> * * @param fieldName the field name * @param obj the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final Object obj) { style.append(buffer, fieldName, obj, null); return this; } /** * <p>Append to the toString an Object * value.</p> * * @param fieldName the field name * @param obj the value to add to the <code>toString * @param fullDetail <code>true for detail, * <code>false for summary info * @return this */ public ToStringBuilder append(final String fieldName, final Object obj, final boolean fullDetail) { style.append(buffer, fieldName, obj, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an Object * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final Object[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString an Object * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final Object[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Append to the toString an short * value.</p> * * @param fieldName the field name * @param value the value to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final short value) { style.append(buffer, fieldName, value); return this; } /** * <p>Append to the toString a short * array.</p> * * @param fieldName the field name * @param array the array to add to the <code>toString * @return this */ public ToStringBuilder append(final String fieldName, final short[] array) { style.append(buffer, fieldName, array, null); return this; } /** * <p>Append to the toString a short * array.</p> * * <p>A boolean parameter controls the level of detail to show. * Setting <code>true will output the array in full. Setting * <code>false will output a summary, typically the size of * the array. * * @param fieldName the field name * @param array the array to add to the <code>toString * @param fullDetail <code>true for detail, false * for summary info * @return this */ public ToStringBuilder append(final String fieldName, final short[] array, final boolean fullDetail) { style.append(buffer, fieldName, array, Boolean.valueOf(fullDetail)); return this; } /** * <p>Appends with the same format as the default Object toString() * </code> method. Appends the class name followed by * {@link System#identityHashCode(java.lang.Object)}.</p> * * @param srcObject the <code>Object whose class name and id to output * @return this * @since 2.0 */ public ToStringBuilder appendAsObjectToString(final Object srcObject) { ObjectUtils.identityToString(this.getStringBuffer(), srcObject); return this; } //---------------------------------------------------------------------------- /** * <p>Append the toString from the superclass.

* * <p>This method assumes that the superclass uses the same ToStringStyle * as this one.</p> * * <p>If superToString is null, no change is made.

* * @param superToString the result of <code>super.toString() * @return this * @since 2.0 */ public ToStringBuilder appendSuper(final String superToString) { if (superToString != null) { style.appendSuper(buffer, superToString); } return this; } /** * <p>Append the toString from another object.

* * <p>This method is useful where a class delegates most of the implementation of * its properties to another class. You can then call <code>toString() on * the other class and pass the result into this method.</p> * * <pre> * private AnotherObject delegate; * private String fieldInThisClass; * * public String toString() { * return new ToStringBuilder(this). * appendToString(delegate.toString()). * append(fieldInThisClass). * toString(); * }</pre> * * <p>This method assumes that the other object uses the same ToStringStyle * as this one.</p> * * <p>If the toString is null, no change is made.

* * @param toString the result of <code>toString() on another object * @return this * @since 2.0 */ public ToStringBuilder appendToString(final String toString) { if (toString != null) { style.appendToString(buffer, toString); } return this; } /** * <p>Returns the Object being output.

* * @return The object being output. * @since 2.0 */ public Object getObject() { return object; } /** * <p>Gets the StringBuffer being populated.

* * @return the <code>StringBuffer being populated */ public StringBuffer getStringBuffer() { return buffer; } //---------------------------------------------------------------------------- /** * <p>Gets the ToStringStyle being used.

* * @return the <code>ToStringStyle being used * @since 2.0 */ public ToStringStyle getStyle() { return style; } /** * <p>Returns the built toString.

* * <p>This method appends the end of data indicator, and can only be called once. * Use {@link #getStringBuffer} to get the current string state.</p> * * <p>If the object is null, return the style's nullText

* * @return the String <code>toString */ @Override public String toString() { if (this.getObject() == null) { this.getStringBuffer().append(this.getStyle().getNullText()); } else { style.appendEnd(this.getStringBuffer(), this.getObject()); } return this.getStringBuffer().toString(); } /** * Returns the String that was build as an object representation. The * default implementation utilizes the {@link #toString()} implementation. * * @return the String <code>toString * * @see #toString() * * @since 3.0 */ @Override public String build() { return toString(); } }

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