Package org.apache.commons.text

Class StringSubstitutor

java.lang.Object
org.apache.commons.text.StringSubstitutor
public class StringSubstitutor extends Object
Substitutes variables within a string by values.

This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is ${variableName}. The prefix and suffix can be changed via constructors and set methods.

Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying a custom variable resolver.

Using System Properties

The simplest example is to use this class to replace Java System properties. For example: 

 StringSubstitutor
     .replaceSystemProperties("You are running with java.version = ${java.version} and os.name = ${os.name}.");

Using a Custom Map

Typical usage of this class follows the following pattern:

  • Create and initialize a StringSubstitutor with the map that contains the values for the variables you want to make available.
  • Optionally set attributes like variable prefix, variable suffix, default value delimiter, and so on.
  • Call the replace() method with in the source text for interpolation.
  • The returned text contains all variable references (as long as their values are known) as resolved.

For example: 

 // Build map
 Map<String, String> valuesMap = new HashMap<>();
 valuesMap.put("animal", "quick brown fox");
 valuesMap.put("target", "lazy dog");
 String templateString = "The ${animal} jumped over the ${target}.";

 // Build StringSubstitutor
 StringSubstitutor sub = new StringSubstitutor(valuesMap);

 // Replace
 String resolvedString = sub.replace(templateString);

yielding: 

 "The quick brown fox jumped over the lazy dog."

Providing Default Values

You can set a default value for unresolved variables. The default value for a variable can be appended to the variable name after the variable default value delimiter. The default value of the variable default value delimiter is ":-", as in bash and other *nix shells.

You can set the variable value delimiter with setValueDelimiterMatcher(StringMatcher), setValueDelimiter(char) or setValueDelimiter(String).

For example: 

 // Build map
 Map<String, String> valuesMap = new HashMap<>();
 valuesMap.put("animal", "quick brown fox");
 valuesMap.put("target", "lazy dog");
 String templateString = "The ${animal} jumped over the ${target} ${undefined.number:-1234567890} times.";

 // Build StringSubstitutor
 StringSubstitutor sub = new StringSubstitutor(valuesMap);

 // Replace
 String resolvedString = sub.replace(templateString);

yielding: 

 "The quick brown fox jumped over the lazy dog 1234567890 times."

StringSubstitutor supports throwing exceptions for unresolved variables, you enable this by setting calling setEnableUndefinedVariableException(boolean) with true.

Reusing Instances

Static shortcut methods cover the most common use cases. If multiple replace operations are to be performed, creating and reusing an instance of this class will be more efficient.

Using Interpolation

The default interpolator lets you use string lookups like: 

 final StringSubstitutor interpolator = StringSubstitutor.createInterpolator();
 final String text = interpolator.replace(
       "Base64 Decoder:        ${base64Decoder:SGVsbG9Xb3JsZCE=}\n"
     + "Base64 Encoder:        ${base64Encoder:HelloWorld!}\n"
     + "Java Constant:         ${const:java.awt.event.KeyEvent.VK_ESCAPE}\n"
     + "Date:                  ${date:yyyy-MM-dd}\n"
     + "Environment Variable:  ${env:USERNAME}\n"
     + "File Content:          ${file:UTF-8:src/test/resources/document.properties}\n"
     + "Java:                  ${java:version}\n"
     + "Localhost:             ${localhost:canonical-name}\n"
     + "Properties File:       ${properties:src/test/resources/document.properties::mykey}\n"
     + "Resource Bundle:       ${resourceBundle:org.apache.commons.text.example.testResourceBundleLookup:mykey}\n"
     + "System Property:       ${sys:user.dir}\n"
     + "URL Decoder:           ${urlDecoder:Hello%20World%21}\n"
     + "URL Encoder:           ${urlEncoder:Hello World!}\n"
     + "XML XPath:             ${xml:src/test/resources/document.xml:/root/path/to/node}\n");

For documentation and a full list of available lookups, see StringLookupFactory.

NOTE: The list of lookups available by default in createInterpolator() changed in version 1.10.0. See the StringLookupFactory documentation for details and an explanation on how to reproduce the previous functionality.

Using Recursive Variable Replacement

Variable replacement can work recursively by calling setEnableSubstitutionInVariables(boolean) with true. If a variable value contains a variable then that variable will also be replaced. Cyclic replacements are detected and will throw an exception.

You can get the replace result to contain a variable prefix. For example: 

 "The variable ${${name}} must be used."

If the value of the "name" variable is "x", then only the variable "name" is replaced resulting in: 

 "The variable ${x} must be used."

To achieve this effect there are two possibilities: Either set a different prefix and suffix for variables which do not conflict with the result text you want to produce. The other possibility is to use the escape character, by default '$'. If this character is placed before a variable reference, this reference is ignored and won't be replaced. For example: 

 "The variable $${${name}} must be used."

In some complex scenarios you might even want to perform substitution in the names of variables, for instance 

 ${jre-${java.specification.version}}

StringSubstitutor supports this recursive substitution in variable names, but it has to be enabled explicitly by calling setEnableSubstitutionInVariables(boolean) with true.

Thread Safety

This class is not thread safe.

Since:
1.3

  • Field Details

  • Constructor Details

    • StringSubstitutor

      public StringSubstitutor()
      Constructs a new instance with defaults for variable prefix and suffix and the escaping character.

    • StringSubstitutor

      public StringSubstitutor(Map<String,V> valueMap)
      Constructs a new initialized instance. Uses defaults for variable prefix and suffix and the escaping character.
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      valueMap - the map with the variables' values, may be null

    • StringSubstitutor

      public StringSubstitutor(Map<String,V> valueMap, String prefix, String suffix)
      Constructs a new initialized instance. Uses a default escaping character.
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      valueMap - the map with the variables' values, may be null
      prefix - the prefix for variables, not null
      suffix - the suffix for variables, not null
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(Map<String,V> valueMap, String prefix, String suffix, char escape)
      Constructs a new initialized instance.
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      valueMap - the map with the variables' values, may be null
      prefix - the prefix for variables, not null
      suffix - the suffix for variables, not null
      escape - the escape character
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(Map<String,V> valueMap, String prefix, String suffix, char escape, String valueDelimiter)
      Constructs a new initialized instance.
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      valueMap - the map with the variables' values, may be null
      prefix - the prefix for variables, not null
      suffix - the suffix for variables, not null
      escape - the escape character
      valueDelimiter - the variable default value delimiter, may be null
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(StringLookup variableResolver)
      Constructs a new initialized instance.
      Parameters:
      variableResolver - the variable resolver, may be null

    • StringSubstitutor

      public StringSubstitutor(StringLookup variableResolver, String prefix, String suffix, char escape)
      Constructs a new initialized instance.
      Parameters:
      variableResolver - the variable resolver, may be null
      prefix - the prefix for variables, not null
      suffix - the suffix for variables, not null
      escape - the escape character
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(StringLookup variableResolver, String prefix, String suffix, char escape, String valueDelimiter)
      Constructs a new initialized instance.
      Parameters:
      variableResolver - the variable resolver, may be null
      prefix - the prefix for variables, not null
      suffix - the suffix for variables, not null
      escape - the escape character
      valueDelimiter - the variable default value delimiter string, may be null
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(StringLookup variableResolver, StringMatcher prefixMatcher, StringMatcher suffixMatcher, char escape)
      Constructs a new initialized instance.
      Parameters:
      variableResolver - the variable resolver, may be null
      prefixMatcher - the prefix for variables, not null
      suffixMatcher - the suffix for variables, not null
      escape - the escape character
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(StringLookup variableResolver, StringMatcher prefixMatcher, StringMatcher suffixMatcher, char escape, StringMatcher valueDelimiterMatcher)
      Constructs a new initialized instance.
      Parameters:
      variableResolver - the variable resolver, may be null
      prefixMatcher - the prefix for variables, not null
      suffixMatcher - the suffix for variables, not null
      escape - the escape character
      valueDelimiterMatcher - the variable default value delimiter matcher, may be null
      Throws:
      IllegalArgumentException - if the prefix or suffix is null

    • StringSubstitutor

      public StringSubstitutor(StringSubstitutor other)
      Creates a new instance based on the given StringSubstitutor.
      Parameters:
      other - The StringSubstitutor used as the source.
      Since:
      1.9

  • Method Details

    • createInterpolator

      public static StringSubstitutor createInterpolator()
      Creates a new instance using the interpolator string lookup StringLookupFactory.interpolatorStringLookup().

      This StringSubstitutor lets you perform substitutions like: 

       StringSubstitutor.createInterpolator().replace(
   "OS name: ${sys:os.name}, user: ${env:USER}");

      The table below lists the lookups available by default in the returned instance. These may be modified through the use of the "org.apache.commons.text.lookup.StringLookupFactory.defaultStringLookups" system property, as described in the StringLookupFactory documentation.

      NOTE: The list of lookups available by default changed in version 1.10.0. Configuration via system property (as mentioned above) may be necessary to reproduce previous functionality.

      Default Lookups
      Key Lookup
      "base64Decoder" StringLookupFactory.base64DecoderStringLookup()
      "base64Encoder" StringLookupFactory.base64EncoderStringLookup()
      "const" StringLookupFactory.constantStringLookup()
      "date" StringLookupFactory.dateStringLookup()
      "env" StringLookupFactory.environmentVariableStringLookup()
      "file" StringLookupFactory.fileStringLookup()
      "java" StringLookupFactory.javaPlatformStringLookup()
      "localhost" StringLookupFactory.localHostStringLookup()
      "properties" StringLookupFactory.propertiesStringLookup()
      "resourceBundle" StringLookupFactory.resourceBundleStringLookup()
      "sys" StringLookupFactory.systemPropertyStringLookup()
      "urlDecoder" StringLookupFactory.urlDecoderStringLookup()
      "urlEncoder" StringLookupFactory.urlEncoderStringLookup()
      "xml" StringLookupFactory.xmlStringLookup()
      "xmlDecoder" StringLookupFactory.xmlDecoderStringLookup()
      "xmlEncoder" StringLookupFactory.xmlEncoderStringLookup()
      Returns:
      a new instance using the interpolator string lookup.
      Since:
      1.8
      See Also:

    • replace

      public static <V> String replace(Object source, Map<String,V> valueMap)
      Replaces all the occurrences of variables in the given source object with their matching values from the map.
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      source - the source text containing the variables to substitute, null returns null
      valueMap - the map with the values, may be null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if a variable is not found and enableUndefinedVariableException is true

    • replace

      public static <V> String replace(Object source, Map<String,V> valueMap, String prefix, String suffix)
      Replaces all the occurrences of variables in the given source object with their matching values from the map. This method allows to specify a custom variable prefix and suffix
      Type Parameters:
      V - the type of the values in the map
      Parameters:
      source - the source text containing the variables to substitute, null returns null
      valueMap - the map with the values, may be null
      prefix - the prefix of variables, not null
      suffix - the suffix of variables, not null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if the prefix or suffix is null
      IllegalArgumentException - if a variable is not found and enableUndefinedVariableException is true

    • replace

      public static String replace(Object source, Properties valueProperties)
      Replaces all the occurrences of variables in the given source object with their matching values from the properties.
      Parameters:
      source - the source text containing the variables to substitute, null returns null
      valueProperties - the properties with values, may be null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if a variable is not found and enableUndefinedVariableException is true

    • replaceSystemProperties

      public static String replaceSystemProperties(Object source)
      Replaces all the occurrences of variables in the given source object with their matching values from the system properties.
      Parameters:
      source - the source text containing the variables to substitute, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if a variable is not found and enableUndefinedVariableException is true

    • getEscapeChar

      public char getEscapeChar()
      Returns the escape character.
      Returns:
      The character used for escaping variable references

    • getStringLookup

      public StringLookup getStringLookup()
      Gets the StringLookup that is used to lookup variables.
      Returns:
      The StringLookup

    • getValueDelimiterMatcher

      public StringMatcher getValueDelimiterMatcher()
      Gets the variable default value delimiter matcher currently in use.

      The variable default value delimiter is the character or characters that delimit the variable name and the variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default value delimiter matches.

      If it returns null, then the variable default value resolution is disabled.

      Returns:
      The variable default value delimiter matcher in use, may be null

    • getVariablePrefixMatcher

      public StringMatcher getVariablePrefixMatcher()
      Gets the variable prefix matcher currently in use.

      The variable prefix is the character or characters that identify the start of a variable. This prefix is expressed in terms of a matcher allowing advanced prefix matches.

      Returns:
      The prefix matcher in use

    • getVariableSuffixMatcher

      public StringMatcher getVariableSuffixMatcher()
      Gets the variable suffix matcher currently in use.

      The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed in terms of a matcher allowing advanced suffix matches.

      Returns:
      The suffix matcher in use

    • isDisableSubstitutionInValues

      public boolean isDisableSubstitutionInValues()
      Returns a flag whether substitution is disabled in variable values.If set to true, the values of variables can contain other variables will not be processed and substituted original variable is evaluated, e.g. 
       Map<String, String> valuesMap = new HashMap<>();
 valuesMap.put("name", "Douglas ${surname}");
 valuesMap.put("surname", "Crockford");
 String templateString = "Hi ${name}";
 StrSubstitutor sub = new StrSubstitutor(valuesMap);
 String resolvedString = sub.replace(templateString);
      yielding: 
            Hi Douglas ${surname}
      Returns:
      The substitution in variable values flag

    • isEnableSubstitutionInVariables

      public boolean isEnableSubstitutionInVariables()
      Returns a flag whether substitution is done in variable names.
      Returns:
      The substitution in variable names flag

    • isEnableUndefinedVariableException

      public boolean isEnableUndefinedVariableException()
      Returns a flag whether exception can be thrown upon undefined variable.
      Returns:
      The fail on undefined variable flag

    • isPreserveEscapes

      public boolean isPreserveEscapes()
      Returns the flag controlling whether escapes are preserved during substitution.
      Returns:
      The preserve escape flag

    • replace

      public String replace(char[] source)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source array as a template. The array is not altered by this method.
      Parameters:
      source - the character array to replace in, not altered, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(char[] source, int offset, int length)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source array as a template. The array is not altered by this method.

      Only the specified portion of the array will be processed. The rest of the array is not processed, and is not returned.

      Parameters:
      source - the character array to replace in, not altered, null returns null
      offset - the start offset within the array, must be valid
      length - the length within the array to be processed, must be valid
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception
      StringIndexOutOfBoundsException - if offset is not in the range 0 <= offset <= chars.length
      StringIndexOutOfBoundsException - if length < 0
      StringIndexOutOfBoundsException - if offset + length > chars.length

    • replace

      public String replace(CharSequence source)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source as a template. The source is not altered by this method.
      Parameters:
      source - the buffer to use as a template, not changed, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(CharSequence source, int offset, int length)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source as a template. The source is not altered by this method.

      Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not returned.

      Parameters:
      source - the buffer to use as a template, not changed, null returns null
      offset - the start offset within the array, must be valid
      length - the length within the array to be processed, must be valid
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(Object source)
      Replaces all the occurrences of variables in the given source object with their matching values from the resolver. The input source object is converted to a string using toString and is not altered.
      Parameters:
      source - the source to replace in, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if a variable is not found and enableUndefinedVariableException is true

    • replace

      public String replace(String source)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template.
      Parameters:
      source - the string to replace in, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(String source, int offset, int length)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source string as a template.

      Only the specified portion of the string will be processed. The rest of the string is not processed, and is not returned.

      Parameters:
      source - the string to replace in, null returns null
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception
      StringIndexOutOfBoundsException - if offset is not in the range 0 <= offset <= source.length()
      StringIndexOutOfBoundsException - if length < 0
      StringIndexOutOfBoundsException - if offset + length > source.length()

    • replace

      public String replace(StringBuffer source)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source buffer as a template. The buffer is not altered by this method.
      Parameters:
      source - the buffer to use as a template, not changed, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(StringBuffer source, int offset, int length)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source buffer as a template. The buffer is not altered by this method.

      Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, and is not returned.

      Parameters:
      source - the buffer to use as a template, not changed, null returns null
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(TextStringBuilder source)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source builder as a template. The builder is not altered by this method.
      Parameters:
      source - the builder to use as a template, not changed, null returns null
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replace

      public String replace(TextStringBuilder source, int offset, int length)
      Replaces all the occurrences of variables with their matching values from the resolver using the given source builder as a template. The builder is not altered by this method.

      Only the specified portion of the builder will be processed. The rest of the builder is not processed, and is not returned.

      Parameters:
      source - the builder to use as a template, not changed, null returns null
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      The result of the replace operation
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replaceIn

      public boolean replaceIn(StringBuffer source)
      Replaces all the occurrences of variables within the given source buffer with their matching values from the resolver. The buffer is updated with the result.
      Parameters:
      source - the buffer to replace in, updated, null returns zero
      Returns:
      true if altered

    • replaceIn

      public boolean replaceIn(StringBuffer source, int offset, int length)
      Replaces all the occurrences of variables within the given source buffer with their matching values from the resolver. The buffer is updated with the result.

      Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is not deleted.

      Parameters:
      source - the buffer to replace in, updated, null returns zero
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      true if altered
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replaceIn

      public boolean replaceIn(StringBuilder source)
      Replaces all the occurrences of variables within the given source buffer with their matching values from the resolver. The buffer is updated with the result.
      Parameters:
      source - the buffer to replace in, updated, null returns zero
      Returns:
      true if altered

    • replaceIn

      public boolean replaceIn(StringBuilder source, int offset, int length)
      Replaces all the occurrences of variables within the given source builder with their matching values from the resolver. The builder is updated with the result.

      Only the specified portion of the buffer will be processed. The rest of the buffer is not processed, but it is not deleted.

      Parameters:
      source - the buffer to replace in, updated, null returns zero
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      true if altered
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replaceIn

      public boolean replaceIn(TextStringBuilder source)
      Replaces all the occurrences of variables within the given source builder with their matching values from the resolver.
      Parameters:
      source - the builder to replace in, updated, null returns zero
      Returns:
      true if altered
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • replaceIn

      public boolean replaceIn(TextStringBuilder source, int offset, int length)
      Replaces all the occurrences of variables within the given source builder with their matching values from the resolver.

      Only the specified portion of the builder will be processed. The rest of the builder is not processed, but it is not deleted.

      Parameters:
      source - the builder to replace in, null returns zero
      offset - the start offset within the source, must be valid
      length - the length within the source to be processed, must be valid
      Returns:
      true if altered
      Throws:
      IllegalArgumentException - if variable is not found when its allowed to throw exception

    • resolveVariable

      protected String resolveVariable(String variableName, TextStringBuilder buf, int startPos, int endPos)
      Internal method that resolves the value of a variable.

      Most users of this class do not need to call this method. This method is called automatically by the substitution process.

      Writers of subclasses can override this method if they need to alter how each substitution occurs. The method is passed the variable's name and must return the corresponding value. This implementation uses the getStringLookup() with the variable's name as the key.

      Parameters:
      variableName - the name of the variable, not null
      buf - the buffer where the substitution is occurring, not null
      startPos - the start position of the variable including the prefix, valid
      endPos - the end position of the variable including the suffix, valid
      Returns:
      The variable's value or null if the variable is unknown

    • setDisableSubstitutionInValues

      public StringSubstitutor setDisableSubstitutionInValues(boolean disableSubstitutionInValues)
      Sets a flag whether substitution is done in variable values (recursive).
      Parameters:
      disableSubstitutionInValues - true if substitution in variable value are disabled
      Returns:
      this, to enable chaining

    • setEnableSubstitutionInVariables

      public StringSubstitutor setEnableSubstitutionInVariables(boolean enableSubstitutionInVariables)
      Sets a flag whether substitution is done in variable names. If set to true, the names of variables can contain other variables which are processed first before the original variable is evaluated, e.g. ${jre-${java.version}}. The default value is false.
      Parameters:
      enableSubstitutionInVariables - the new value of the flag
      Returns:
      this, to enable chaining

    • setEnableUndefinedVariableException

      public StringSubstitutor setEnableUndefinedVariableException(boolean failOnUndefinedVariable)
      Sets a flag whether exception should be thrown if any variable is undefined.
      Parameters:
      failOnUndefinedVariable - true if exception should be thrown on undefined variable
      Returns:
      this, to enable chaining

    • setEscapeChar

      public StringSubstitutor setEscapeChar(char escapeCharacter)
      Sets the escape character. If this character is placed before a variable reference in the source text, this variable will be ignored.
      Parameters:
      escapeCharacter - the escape character (0 for disabling escaping)
      Returns:
      this, to enable chaining

    • setPreserveEscapes

      public StringSubstitutor setPreserveEscapes(boolean preserveEscapes)
      Sets a flag controlling whether escapes are preserved during substitution. If set to true, the escape character is retained during substitution (e.g. $${this-is-escaped} remains $${this-is-escaped}). If set to false, the escape character is removed during substitution (e.g. $${this-is-escaped} becomes ${this-is-escaped}). The default value is false
      Parameters:
      preserveEscapes - true if escapes are to be preserved
      Returns:
      this, to enable chaining

    • setValueDelimiter

      public StringSubstitutor setValueDelimiter(char valueDelimiter)
      Sets the variable default value delimiter to use.

      The variable default value delimiter is the character or characters that delimit the variable name and the variable default value. This method allows a single character variable default value delimiter to be easily set.

      Parameters:
      valueDelimiter - the variable default value delimiter character to use
      Returns:
      this, to enable chaining

    • setValueDelimiter

      public StringSubstitutor setValueDelimiter(String valueDelimiter)
      Sets the variable default value delimiter to use.

      The variable default value delimiter is the character or characters that delimit the variable name and the variable default value. This method allows a string variable default value delimiter to be easily set.

      If the valueDelimiter is null or empty string, then the variable default value resolution becomes disabled.

      Parameters:
      valueDelimiter - the variable default value delimiter string to use, may be null or empty
      Returns:
      this, to enable chaining

    • setValueDelimiterMatcher

      public StringSubstitutor setValueDelimiterMatcher(StringMatcher valueDelimiterMatcher)
      Sets the variable default value delimiter matcher to use.

      The variable default value delimiter is the character or characters that delimit the variable name and the variable default value. This delimiter is expressed in terms of a matcher allowing advanced variable default value delimiter matches.

      If the valueDelimiterMatcher is null, then the variable default value resolution becomes disabled.

      Parameters:
      valueDelimiterMatcher - variable default value delimiter matcher to use, may be null
      Returns:
      this, to enable chaining

    • setVariablePrefix

      public StringSubstitutor setVariablePrefix(char prefix)
      Sets the variable prefix to use.

      The variable prefix is the character or characters that identify the start of a variable. This method allows a single character prefix to be easily set.

      Parameters:
      prefix - the prefix character to use
      Returns:
      this, to enable chaining

    • setVariablePrefix

      public StringSubstitutor setVariablePrefix(String prefix)
      Sets the variable prefix to use.

      The variable prefix is the character or characters that identify the start of a variable. This method allows a string prefix to be easily set.

      Parameters:
      prefix - the prefix for variables, not null
      Returns:
      this, to enable chaining
      Throws:
      IllegalArgumentException - if the prefix is null

    • setVariablePrefixMatcher

      public StringSubstitutor setVariablePrefixMatcher(StringMatcher prefixMatcher)
      Sets the variable prefix matcher currently in use.

      The variable prefix is the character or characters that identify the start of a variable. This prefix is expressed in terms of a matcher allowing advanced prefix matches.

      Parameters:
      prefixMatcher - the prefix matcher to use, null ignored
      Returns:
      this, to enable chaining
      Throws:
      IllegalArgumentException - if the prefix matcher is null

    • setVariableResolver

      public StringSubstitutor setVariableResolver(StringLookup variableResolver)
      Sets the VariableResolver that is used to lookup variables.
      Parameters:
      variableResolver - the VariableResolver
      Returns:
      this, to enable chaining

    • setVariableSuffix

      public StringSubstitutor setVariableSuffix(char suffix)
      Sets the variable suffix to use.

      The variable suffix is the character or characters that identify the end of a variable. This method allows a single character suffix to be easily set.

      Parameters:
      suffix - the suffix character to use
      Returns:
      this, to enable chaining

    • setVariableSuffix

      public StringSubstitutor setVariableSuffix(String suffix)
      Sets the variable suffix to use.

      The variable suffix is the character or characters that identify the end of a variable. This method allows a string suffix to be easily set.

      Parameters:
      suffix - the suffix for variables, not null
      Returns:
      this, to enable chaining
      Throws:
      IllegalArgumentException - if the suffix is null

    • setVariableSuffixMatcher

      public StringSubstitutor setVariableSuffixMatcher(StringMatcher suffixMatcher)
      Sets the variable suffix matcher currently in use.

      The variable suffix is the character or characters that identify the end of a variable. This suffix is expressed in terms of a matcher allowing advanced suffix matches.

      Parameters:
      suffixMatcher - the suffix matcher to use, null ignored
      Returns:
      this, to enable chaining
      Throws:
      IllegalArgumentException - if the suffix matcher is null

    • substitute

      protected boolean substitute(TextStringBuilder builder, int offset, int length)
      Internal method that substitutes the variables.

      Most users of this class do not need to call this method. This method will be called automatically by another (public) method.

      Writers of subclasses can override this method if they need access to the substitution process at the start or end.

      Parameters:
      builder - the string builder to substitute into, not null
      offset - the start offset within the builder, must be valid
      length - the length within the builder to be processed, must be valid
      Returns:
      true if altered

    • toString

      public String toString()
      Returns a string representation of the object.
      Overrides:
      toString in class Object
      Returns:
      a string representation of the object.
      Since:
      1.11.0