What is the easiest way to parse an INI file in Java

Question

I am writing a drop-in replacement for a legacy application in Java   One of the requirements is that the ini files that the older application used have to be read as-is into the new Java Application   The format of this ini files is the common windows style  with header sections and key value pairs  using   as the character for commenting   I tried using the Properties class from Java  but of course that won t work if there is name clashes between different headers   So the question is  what would be the easiest way to read in this INI file and access the keys

User · Answer

Or with standard Java API you can use java util Properties   Properties props   new Properties    try  FileInputStream in   new FileInputStream path         props load in

User · Answer

hoat4 s solution is very elegant and simple   It works for all sane ini files   However  I have seen many that have un-escaped space characters in the key  To solve this  I have downloaded and modified a copy of java util Properties   Though this is a little unorthodox  and short-term  the actual mods were but a few lines and quite simple   I will be puting forward a proposal to the JDK community to include the changes  By adding an internal class variable   private boolean  spaceCharOn   false    I control the processing related to scanning for the key value separation point  I replaced the space characters search code with a small private method that returns a boolean depending on the state of the above variable   private boolean isSpaceSeparator char c        if   spaceCharOn            return  c           c      t     c      f          else           return  c      t     c      f              This method is used in two places within the private method load0       There is also a public method to switch it on  but it would be better to use the original version of Properties if the space separator is not an issue for your application   If there is interest  I would be willing to post the code to my IniFile java file   It works with either version of Properties

User · Answer

As simple as 80 lines   package windows prefs   import java io BufferedReader  import java io FileReader  import java io IOException  import java util HashMap  import java util Map  import java util regex Matcher  import java util regex Pattern   public class IniFile       private Pattern   section    Pattern compile     s                s         private Pattern   keyValue   Pattern compile     s                     private Map lt  String        Map lt  String           String  gt  gt    entries    new HashMap lt  gt         public IniFile  String path   throws IOException         load  path             public void load  String path   throws IOException         try  BufferedReader br   new BufferedReader  new FileReader  path                String line           String section   null           while   line   br readLine       null                 Matcher m    section matcher  line                if  m matches                     section   m group  1   trim                              else if  section    null                    m    keyValue matcher  line                   if  m matches                        String key     m group  1   trim                      String value   m group  2   trim                      Map lt  String  String  gt  kv    entries get  section                      if  kv    null                           entries put  section  kv   new HashMap lt  gt                                               kv put  key  value                                                               public String getString  String section  String key  String defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return kv get  key             public int getInt  String section  String key  int defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Integer parseInt  kv get  key              public float getFloat  String section  String key  float defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Float parseFloat  kv get  key              public double getDouble  String section  String key  double defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Double parseDouble  kv get  key

User · Answer

I personally prefer Confucious   It is nice  as it doesn t require any external dependencies  it s tiny - only 16K  and automatically loads your ini file on initialization  E g   Configurable config   Configuration getInstance      String host   config getStringValue  host       int port   config getIntValue  port     new Connection host  port

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Another option is Apache Commons Config also has a class for loading from INI files   It does have some runtime dependencies  but for INI files it should only require Commons collections  lang  and logging     I ve used Commons Config on projects with their properties and XML configurations   It is very easy to use and supports some pretty powerful features

User · Answer

I personally prefer Confucious   It is nice  as it doesn t require any external dependencies  it s tiny - only 16K  and automatically loads your ini file on initialization  E g   Configurable config   Configuration getInstance      String host   config getStringValue  host       int port   config getIntValue  port     new Connection host  port

User · Answer

Another option is Apache Commons Config also has a class for loading from INI files   It does have some runtime dependencies  but for INI files it should only require Commons collections  lang  and logging     I ve used Commons Config on projects with their properties and XML configurations   It is very easy to use and supports some pretty powerful features

User · Answer

Here s a simple  yet powerful example  using the apache class HierarchicalINIConfiguration   HierarchicalINIConfiguration iniConfObj   new HierarchicalINIConfiguration iniFile        Get Section names in ini file      Set setOfSections   iniConfObj getSections    Iterator sectionNames   setOfSections iterator     while sectionNames hasNext       String sectionName   sectionNames next   toString      SubnodeConfiguration sObj   iniObj getSection sectionName    Iterator it1     sObj getKeys         while  it1 hasNext             Get element     Object key   it1 next        System out print  Key     key toString        Value                            sObj getString key toString        n        Commons Configuration has a number of runtime dependencies   At a minimum  commons-lang and commons-logging are required   Depending on what you re doing with it  you may require additional libraries  see previous link for details

User · Answer

It is just as simple as this         import java io FileInputStream    import java io FileInputStream   Properties prop   new Properties      c   myapp  config ini is the location of the ini file   ini file should look like host localhost prop load new FileInputStream  c   myapp  config ini     String host   prop getProperty  host

User · Answer

As simple as 80 lines   package windows prefs   import java io BufferedReader  import java io FileReader  import java io IOException  import java util HashMap  import java util Map  import java util regex Matcher  import java util regex Pattern   public class IniFile       private Pattern   section    Pattern compile     s                s         private Pattern   keyValue   Pattern compile     s                     private Map lt  String        Map lt  String           String  gt  gt    entries    new HashMap lt  gt         public IniFile  String path   throws IOException         load  path             public void load  String path   throws IOException         try  BufferedReader br   new BufferedReader  new FileReader  path                String line           String section   null           while   line   br readLine       null                 Matcher m    section matcher  line                if  m matches                     section   m group  1   trim                              else if  section    null                    m    keyValue matcher  line                   if  m matches                        String key     m group  1   trim                      String value   m group  2   trim                      Map lt  String  String  gt  kv    entries get  section                      if  kv    null                           entries put  section  kv   new HashMap lt  gt                                               kv put  key  value                                                               public String getString  String section  String key  String defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return kv get  key             public int getInt  String section  String key  int defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Integer parseInt  kv get  key              public float getFloat  String section  String key  float defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Float parseFloat  kv get  key              public double getDouble  String section  String key  double defaultvalue           Map lt  String  String  gt  kv    entries get  section          if  kv    null              return defaultvalue                return Double parseDouble  kv get  key

User · Answer

Using answer by  Aerospace  I realized that it is legitimate for INI files to have sections without any key-values  In this case  addition to the top-level map should happen before any key-values are found  ex  minimally updated for Java 8               Path location                    try  BufferedReader br   new BufferedReader new FileReader location toFile                        String line                  String section   null                  while   line   br readLine       null                        Matcher m   this section matcher line                       if  m matches                              section   m group 1  trim                            entries computeIfAbsent section  k - gt  new HashMap lt  gt                            else if  section    null                            m   keyValue matcher line                           if  m matches                                  String key   m group 1  trim                                String value   m group 2  trim                                entries get section  put key  value                                                                                   catch  IOException ex                    System err println  quot Failed to read and parse INI file   quot    location    quot     quot    ex getMessage                     ex printStackTrace System err

User · Answer

It is just as simple as this         import java io FileInputStream    import java io FileInputStream   Properties prop   new Properties      c   myapp  config ini is the location of the ini file   ini file should look like host localhost prop load new FileInputStream  c   myapp  config ini     String host   prop getProperty  host

User · Answer

The library I ve used is ini4j   It is lightweight and parses the ini files with ease   Also it uses no esoteric dependencies to 10 000 other jar files  as one of the design goals was to use only the standard Java API  This is an example on how the library is used   Ini ini   new Ini new File filename    java util prefs Preferences prefs   new IniPreferences ini   System out println  grumpy homePage      prefs node  grumpy   get  homePage   null

User · Answer

The library I ve used is ini4j   It is lightweight and parses the ini files with ease   Also it uses no esoteric dependencies to 10 000 other jar files  as one of the design goals was to use only the standard Java API  This is an example on how the library is used   Ini ini   new Ini new File filename    java util prefs Preferences prefs   new IniPreferences ini   System out println  grumpy homePage      prefs node  grumpy   get  homePage   null

User · Answer

Another option is Apache Commons Config also has a class for loading from INI files   It does have some runtime dependencies  but for INI files it should only require Commons collections  lang  and logging     I ve used Commons Config on projects with their properties and XML configurations   It is very easy to use and supports some pretty powerful features

User · Answer

Or with standard Java API you can use java util Properties   Properties props   new Properties    try  FileInputStream in   new FileInputStream path         props load in

User · Answer

You could try JINIFile  Is a translation of the TIniFile from Delphi  but for java  https   github com SubZane JIniFile

User · Answer

As mentioned  ini4j can be used to achieve this  Let me show one other example   If we have an INI file like this    header  key   value   The following should display value to STDOUT   Ini ini   new Ini new File   path to file     System out println ini get  header    key       Check the tutorials for more examples

User · Answer

The library I ve used is ini4j   It is lightweight and parses the ini files with ease   Also it uses no esoteric dependencies to 10 000 other jar files  as one of the design goals was to use only the standard Java API  This is an example on how the library is used   Ini ini   new Ini new File filename    java util prefs Preferences prefs   new IniPreferences ini   System out println  grumpy homePage      prefs node  grumpy   get  homePage   null

User · Answer

Here s a simple  yet powerful example  using the apache class HierarchicalINIConfiguration   HierarchicalINIConfiguration iniConfObj   new HierarchicalINIConfiguration iniFile        Get Section names in ini file      Set setOfSections   iniConfObj getSections    Iterator sectionNames   setOfSections iterator     while sectionNames hasNext       String sectionName   sectionNames next   toString      SubnodeConfiguration sObj   iniObj getSection sectionName    Iterator it1     sObj getKeys         while  it1 hasNext             Get element     Object key   it1 next        System out print  Key     key toString        Value                            sObj getString key toString        n        Commons Configuration has a number of runtime dependencies   At a minimum  commons-lang and commons-logging are required   Depending on what you re doing with it  you may require additional libraries  see previous link for details

User · Answer

As mentioned  ini4j can be used to achieve this  Let me show one other example   If we have an INI file like this    header  key   value   The following should display value to STDOUT   Ini ini   new Ini new File   path to file     System out println ini get  header    key       Check the tutorials for more examples

User · Answer

In 18 lines  extending the java util Properties to parse into multiple sections   public static Map lt String  Properties gt  parseINI Reader reader  throws IOException       Map lt String  Properties gt  result   new HashMap        new Properties              private Properties section            Override         public Object put Object key  Object value                String header      String  key          value  trim                if  header startsWith       amp  amp  header endsWith                       return result put header substring 1  header length   - 1                            section   new Properties                 else                 return section put key  value                    load reader       return result

User · Answer

The library I ve used is ini4j   It is lightweight and parses the ini files with ease   Also it uses no esoteric dependencies to 10 000 other jar files  as one of the design goals was to use only the standard Java API  This is an example on how the library is used   Ini ini   new Ini new File filename    java util prefs Preferences prefs   new IniPreferences ini   System out println  grumpy homePage      prefs node  grumpy   get  homePage   null

User · Answer

Using answer by  Aerospace  I realized that it is legitimate for INI files to have sections without any key-values  In this case  addition to the top-level map should happen before any key-values are found  ex  minimally updated for Java 8               Path location                    try  BufferedReader br   new BufferedReader new FileReader location toFile                        String line                  String section   null                  while   line   br readLine       null                        Matcher m   this section matcher line                       if  m matches                              section   m group 1  trim                            entries computeIfAbsent section  k - gt  new HashMap lt  gt                            else if  section    null                            m   keyValue matcher line                           if  m matches                                  String key   m group 1  trim                                String value   m group 2  trim                                entries get section  put key  value                                                                                   catch  IOException ex                    System err println  quot Failed to read and parse INI file   quot    location    quot     quot    ex getMessage                     ex printStackTrace System err

User · Answer

Here s a simple  yet powerful example  using the apache class HierarchicalINIConfiguration   HierarchicalINIConfiguration iniConfObj   new HierarchicalINIConfiguration iniFile        Get Section names in ini file      Set setOfSections   iniConfObj getSections    Iterator sectionNames   setOfSections iterator     while sectionNames hasNext       String sectionName   sectionNames next   toString      SubnodeConfiguration sObj   iniObj getSection sectionName    Iterator it1     sObj getKeys         while  it1 hasNext             Get element     Object key   it1 next        System out print  Key     key toString        Value                            sObj getString key toString        n        Commons Configuration has a number of runtime dependencies   At a minimum  commons-lang and commons-logging are required   Depending on what you re doing with it  you may require additional libraries  see previous link for details

User · Answer

Or with standard Java API you can use java util Properties   Properties props   new Properties    try  FileInputStream in   new FileInputStream path         props load in

User · Answer

Or with standard Java API you can use java util Properties   Properties props   new Properties    try  FileInputStream in   new FileInputStream path         props load in

User · Answer

You could try JINIFile  Is a translation of the TIniFile from Delphi  but for java  https   github com SubZane JIniFile

User · Answer

In 18 lines  extending the java util Properties to parse into multiple sections   public static Map lt String  Properties gt  parseINI Reader reader  throws IOException       Map lt String  Properties gt  result   new HashMap        new Properties              private Properties section            Override         public Object put Object key  Object value                String header      String  key          value  trim                if  header startsWith       amp  amp  header endsWith                       return result put header substring 1  header length   - 1                            section   new Properties                 else                 return section put key  value                    load reader       return result

User · Answer

Another option is Apache Commons Config also has a class for loading from INI files   It does have some runtime dependencies  but for INI files it should only require Commons collections  lang  and logging     I ve used Commons Config on projects with their properties and XML configurations   It is very easy to use and supports some pretty powerful features

User · Answer

hoat4 s solution is very elegant and simple   It works for all sane ini files   However  I have seen many that have un-escaped space characters in the key  To solve this  I have downloaded and modified a copy of java util Properties   Though this is a little unorthodox  and short-term  the actual mods were but a few lines and quite simple   I will be puting forward a proposal to the JDK community to include the changes  By adding an internal class variable   private boolean  spaceCharOn   false    I control the processing related to scanning for the key value separation point  I replaced the space characters search code with a small private method that returns a boolean depending on the state of the above variable   private boolean isSpaceSeparator char c        if   spaceCharOn            return  c           c      t     c      f          else           return  c      t     c      f              This method is used in two places within the private method load0       There is also a public method to switch it on  but it would be better to use the original version of Properties if the space separator is not an issue for your application   If there is interest  I would be willing to post the code to my IniFile java file   It works with either version of Properties

User · Answer

Here s a simple  yet powerful example  using the apache class HierarchicalINIConfiguration   HierarchicalINIConfiguration iniConfObj   new HierarchicalINIConfiguration iniFile        Get Section names in ini file      Set setOfSections   iniConfObj getSections    Iterator sectionNames   setOfSections iterator     while sectionNames hasNext       String sectionName   sectionNames next   toString      SubnodeConfiguration sObj   iniObj getSection sectionName    Iterator it1     sObj getKeys         while  it1 hasNext             Get element     Object key   it1 next        System out print  Key     key toString        Value                            sObj getString key toString        n        Commons Configuration has a number of runtime dependencies   At a minimum  commons-lang and commons-logging are required   Depending on what you re doing with it  you may require additional libraries  see previous link for details

[java] What is the easiest way to parse an INI file in Java?

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