How to use Java property files

Question

I have a list of key value pairs of configuration values I want to store as Java property files  and later load and iterate through   Questions    Do I need to store the file in the same package as the class which will load them  or is there any specific location where it should be placed  Does the file need to end in any specific extension or is  txt OK  How can I load the file in the code And how can I iterate through the values inside

User · Answer

This load the properties file       Properties prop   new Properties    InputStream stream          the stream to the file try     prop load stream     finally     stream close        I use to put the  properties file in a directory where I have all the configuration files  I do not put it together with the class that accesses it  but there are no restrictions here   For the name    I use  properties for verbosity sake  I don t think you should name it  properties if you don t want

User · Answer

By default  Java opens it in the working directory of your application  this behavior actually depends on the OS used   To load a file  do   Properties props   new java util Properties    FileInputStream fis new FileInputStream  myfile txt    props load fis    As such  any file extension can be used for property file  Additionally  the file can also be stored anywhere  as long as you can use a FileInputStream   On a related note if you use a modern framework  the framework may provide additionnal ways of opening a property file  For example  Spring provide a ClassPathResource to load a property file using a package name from inside a JAR file    As for iterating through the properties  once the properties are loaded they are stored in the java util Properties object  which offer the propertyNames   method

User · Answer

You can store the file anywhere you like  If you want to keep it in your jar file  you ll want to use Class getResourceAsStream   or ClassLoader getResourceAsStream   to access it  If it s on the file system it s slightly easier  Any extension is fine  although  properties is more common in my experience Load the file using Properties load  passing in an InputStream or a StreamReader if you re using Java 6   If you are using Java 6  I d probably use UTF-8 and a Reader instead of the default ISO-8859-1 encoding for a stream   Iterate through it as you d iterate through a normal Hashtable  which Properties derives from   e g  using keySet    Alternatively  you can use the enumeration returned by propertyNames

User · Answer

If you put the properties file in the same package as class Foo  you can easily load it with   new Properties   load Foo class getResourceAsStream  file properties      Given that Properties extends Hashtable you can iterate over the values in the same manner as you would in a Hashtable   If you use the   properties extension you can get editor support  e g  Eclipse has a properties file editor

User · Answer

in my opinion other ways are deprecated when we can do it very simple as below    PropertySource  classpath application properties   public class SomeClass        Autowired     private Environment env       public void readProperty             env getProperty  language               it is so simple but i think that s the best way   Enjoy

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In order    You can store the file pretty much anywhere  no extension is necessary  Montecristo has illustrated how to load this  That should work fine  propertyNames   gives you an enumeration to iterate through

User · Answer

Here ready static class  import java io    import java util Properties  public class Settings       public static String Get String name String defVal           File configFile   new File Variables SETTINGS FILE           try               FileReader reader   new FileReader configFile               Properties props   new Properties                props load reader               reader close                return props getProperty name             catch  FileNotFoundException ex                   file does not exist             logger error ex               return defVal            catch  IOException ex                   I O error             logger error ex               return defVal            catch  Exception ex               logger error ex               return defVal                      public static Integer Get String name Integer defVal           File configFile   new File Variables SETTINGS FILE           try               FileReader reader   new FileReader configFile               Properties props   new Properties                props load reader               reader close                return Integer valueOf props getProperty name              catch  FileNotFoundException ex                   file does not exist             logger error ex               return defVal            catch  IOException ex                   I O error             logger error ex               return defVal            catch  Exception ex               logger error ex               return defVal                      public static Boolean Get String name Boolean defVal           File configFile   new File Variables SETTINGS FILE           try               FileReader reader   new FileReader configFile               Properties props   new Properties                props load reader               reader close                return Boolean valueOf props getProperty name              catch  FileNotFoundException ex                   file does not exist             logger error ex               return defVal            catch  IOException ex                   I O error             logger error ex               return defVal            catch  Exception ex               logger error ex               return defVal                      public static void Set String name  String value           File configFile   new File Variables SETTINGS FILE           try               Properties props   new Properties                FileReader reader   new FileReader configFile               props load reader               props setProperty name  value toString                 FileWriter writer   new FileWriter configFile               props store writer  Variables SETTINGS COMMENT               writer close              catch  FileNotFoundException ex                   file does not exist             logger error ex             catch  IOException ex                   I O error             logger error ex             catch  Exception ex               logger error ex                       public static void Set String name  Integer value           File configFile   new File Variables SETTINGS FILE           try               Properties props   new Properties                FileReader reader   new FileReader configFile               props load reader               props setProperty name  value toString                 FileWriter writer   new FileWriter configFile               props store writer Variables SETTINGS COMMENT               writer close              catch  FileNotFoundException ex                   file does not exist             logger error ex             catch  IOException ex                   I O error             logger error ex             catch  Exception ex               logger error ex                       public static void Set String name  Boolean value           File configFile   new File Variables SETTINGS FILE           try               Properties props   new Properties                FileReader reader   new FileReader configFile               props load reader               props setProperty name  value toString                 FileWriter writer   new FileWriter configFile               props store writer Variables SETTINGS COMMENT               writer close              catch  FileNotFoundException ex                   file does not exist             logger error ex             catch  IOException ex                   I O error             logger error ex             catch  Exception ex               logger error ex                       Here sample   Settings Set  valueName1   value    String val1 Settings Get  valueName1   value    Settings Set  valueName2  true   Boolean val2 Settings Get  valueName2  true   Settings Set  valueName3  100   Integer val3 Settings Get  valueName3  100

User · Answer

There are many ways to create and read properties files    Store the file in the same package  Recommend  properties extension however you can choose your own  Use theses classes located at java util package     Properties  ListResourceBundle  ResourceBundle classes  To read properties  use iterator or enumerator or direct methods of Properties or java lang System class    ResourceBundle class    ResourceBundle rb   ResourceBundle getBundle  prop       prop properties  System out println rb getString  key       Properties class   Properties ps   new Properties    ps Load new java io FileInputStream  my properties

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Here is another way to iterate over the properties   Enumeration eProps   properties propertyNames    while  eProps hasMoreElements           String key    String  eProps nextElement         String value   properties getProperty key        System out println key       gt      value

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Reading a properties file and loading its contents to Properties  String filename    sample properties   Properties properties   new Properties     input   this getClass   getClassLoader   getResourceAsStream filename   properties load input     The following is the efficient way to iterate over a Properties      for  Entry lt Object  Object gt  entry   properties entrySet               System out println entry getKey         gt      entry getValue

User · Answer

You can pass an InputStream to the Property  so your file can pretty much be anywhere  and called anything   Properties properties   new Properties    try     properties load new FileInputStream  path filename       catch  IOException e              Iterate as   for String key   properties stringPropertyNames        String value   properties getProperty key     System out println key       gt      value

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Example   Properties pro   new Properties    FileInputStream in   new FileInputStream  D  prop prop properties    pro load in   String temp1    String temp2       getting values from property file String username   pro getProperty  usernamev3     key value in prop file  String password   pro getProperty  passwordv3     eg  username  zub  String delimiter                                  password  abc  temp1 username split delimiter   temp2 password split delimiter

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Properties has become legacy  Preferences class is preferred to Properties      A node in a hierarchical collection of preference data  This class allows applications to store and retrieve user and system preference and configuration data  This data is stored persistently in an implementation-dependent backing store  Typical implementations include flat files  OS-specific registries  directory servers and SQL databases  The user of this class needn t be concerned with details of the backing store    Unlike properties which are String based key-value pairs   The Preferences class has several methods used to get and put primitive data in the Preferences data store  We can use only the following types of data    String boolean double float int long byte array   To load the the properties file  either you can provide absolute path Or use getResourceAsStream   if the properties file is present in your classpath   package com mypack test   import java io    import java util    import java util prefs Preferences   public class PreferencesExample        public static void main String args    throws FileNotFoundException           Preferences ps   Preferences userNodeForPackage PreferencesExample class              Load file object         File fileObj   new File  d   data xml            try               FileInputStream fis   new FileInputStream fileObj               ps importPreferences fis               System out println  Prefereces   ps               System out println  Get property1   ps getInt  property1  10               catch  Exception err                err printStackTrace                        xml file    lt  xml version  1 0  encoding  UTF-8   gt   lt  DOCTYPE preferences SYSTEM  http   java sun com dtd preferences dtd  gt   lt preferences EXTERNAL XML VERSION  1 0  gt   lt root type  user  gt   lt map   gt   lt node name  com  gt     lt map   gt     lt node name  mypack  gt       lt map   gt       lt node name  test  gt         lt map gt           lt entry key  property1  value  80    gt           lt entry key  property2  value  Red    gt         lt  map gt       lt  node gt     lt  node gt   lt  node gt   lt  root gt   lt  preferences gt    Have a look at this article on internals of preferences store

User · Answer

You can load the property file suing the following way   InputStream is   new Test   getClass   getClassLoader   getResourceAsStream  app properties            Properties props    new Properties            props load is     And then you can iterate over the map using a lambda expression like    props stringPropertyNames   forEach key - gt                System out println  Key is    key     and Value is    props getProperty key

User · Answer

1  It is good to have your property file in classpath but you can place it anywhere in project   Below is how you load property file from classpath and read all properties   Properties prop   new Properties    InputStream input   null   try        String filename    path to property file       input   getClass   getClassLoader   getResourceAsStream filename       if  input    null            System out println  Sorry  unable to find     filename           return             prop load input        Enumeration lt   gt  e   prop propertyNames        while  e hasMoreElements              String key    String  e nextElement            String value   prop getProperty key           System out println  Key       key      Value       value            catch  IOException ex        ex printStackTrace      finally       if  input    null            try               input close              catch  IOException e                e printStackTrace                        2  Property files have the extension as  properties

User · Answer

In Java 8 to get all your properties   public static Map lt String  String gt  readPropertiesFile String location  throws Exception        Map lt String  String gt  properties   new HashMap lt  gt          Properties props   new Properties        props load new FileInputStream new File location          props forEach  key  value  - gt            properties put key toString    value toString                  return properties

User · Answer

I have written on this property framework for the last year  It will provide of multiple ways to load properties  and have them strongly typed as well   Have a look at http   sourceforge net projects jhpropertiestyp   JHPropertiesTyped will give the developer strongly typed properties  Easy to integrate in existing projects  Handled by a large series for property types  Gives the ability to one-line initialize properties via property IO implementations  Gives the developer the ability to create own property types and property io s   Web demo is also available  screenshots shown above  Also have a standard implementation for a web front end to manage properties  if you choose to use it    Complete documentation  tutorial  javadoc  faq etc is a available on the project webpage

[java] How to use Java property files?

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