Logger entering() method in Java with Examples

The entering() method of a Logger class used to Log a method entry.

There are three types of entering() method depending upon the parameters passed.

1. entering(String sourceClass, String sourceMethod): This method is used to Log a method entry.Actually many times in application development we need to log when we enter in a method of class so this is a convenience method that can be used to log entry to a method. This method logs with message “ENTRY”, log level FINER, and the given sourceMethod and sourceClass are also logged.

   Syntax:

   public void entering(String sourceClass,
                        String sourceMethod)
   

   Parameters: This method accepts two parameters:

   • sourceClass is the name of the class that issued the logging request and
   • sourceMethod is the name of the method that is being entered.

   Return value: This method returns nothing.

   Below program illustrate entering(String sourceClass, String sourceMethod) method:
   Program 1:

   
   

   
   
   

   // Java program to demonstrate // entering(String, String) method    import java.io.IOException; import java.util.List; import java.util.logging.*;    public class GFG {        public static void main(String[] args)         throws SecurityException, IOException     {            // Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());            // Create a file handler object         FileHandler handler             = new FileHandler("logs.txt");         handler.setFormatter(new SimpleFormatter());            // Add file handler as         // handler of logs         logger.addHandler(handler);            // set Logger level()         logger.setLevel(Level.FINER);            // call entering methods with class         // name =  GFG and method name = main         logger.entering(GFG.class.getName(), "main");            // calling again for List class toString()         logger.entering(List.class.getName(), "toString()");     } }

   The output printed on log.txg file is shown below.
   Output:
   

2. entering(String sourceClass, String sourceMethod, Object param1): This method is used to Log a method entry, with one parameter where parameter passed is an object we want to log. Actually many times in application development we need to log when we enter in a method of class so this is a convenience method that can be used to log entry to a method. This method logs with message “ENTRY {0}”, log level FINER, and the given sourceMethod, sourceClass, and parameter are logged.

   Syntax:

   public void entering(String sourceClass,
                        String sourceMethod,
                        Object param1)
   

   Parameters: This method accepts three parameters:

   • sourceClass is the name of the class that issued the logging request and
   • sourceMethod is the name of the method that is being entered.
   • param1: is the parameter to the method being entered.

   Return value: This method returns nothing.

   Below programs illustrate entering(String sourceClass, String sourceMethod, Object param1) method:

   Program 1:

   
   

   
   
   

   // Java program to demonstrate // entering(String, String, Object) method    import java.io.IOException; import java.util.logging.*;    public class GFG {        public static void main(String[] args)         throws SecurityException, IOException     {            // Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());            // Create a file handler object         FileHandler handler             = new FileHandler("logs.txt");         handler.setFormatter(new SimpleFormatter());            // Add file handler as         // handler of logs         logger.addHandler(handler);            // set Logger level()         logger.setLevel(Level.FINER);            // call entering method with class         // name =  GFG and method name = main         logger.entering(             GFG.class.getName(), "main",             new String("Java is Platform Independent"));     } }

   The output printed on log.txt is shown below.
   

3. entering(String sourceClass, String sourceMethod, Object[] params): This method is used to Log a method entry, with an array of parameters. Actually many times in application development we need to log when we enter in a method of class so this is a convenience method that can be used to log entry to a method. This method logs with message “ENTRY” (followed by a format {N} indicator for each entry in the parameter array), log level FINER, and the given sourceMethod, sourceClass, and parameter are logged.

   Syntax:

   public void entering(String sourceClass,
                        String sourceMethod,
                        Object[] params)
   

   Parameters: This method accepts three parameters:

   • sourceClass is the name of the class that issued the logging request and
   • sourceMethod is the name of the method that is being entered.
   • params: is an array of parameters to the method being entered.

   Return value: This method returns nothing.

   Below programs illustrate entering(String sourceClass, String sourceMethod, Object[] params) method:
   Program 1:

   
   

   
   
   

   // Java program to demonstrate // entering(String, String, Object[])  method    import java.io.IOException; import java.util.logging.*;    public class GFG {        public static void main(String[] args)         throws SecurityException, IOException     {            // Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());            // Create a file handler object         FileHandler handler             = new FileHandler("logs.txt");         handler.setFormatter(new SimpleFormatter());            // Add file handler as         // handler of logs         logger.addHandler(handler);            // set Logger level()         logger.setLevel(Level.FINER);            // create a array of String object         String[] methods = {             "main", "ADD", "get", "set"         };            // call entering method with class         // name =  GFG and method name = main         logger.entering(GFG.class.getName(), "main",                         methods);     } }

   The output printed on log.txt is shown below.
   

References:

• https://docs.oracle.com/javase/10/docs/api/java/util/logging/Logger.html#entering(java.lang.String, java.lang.String)
• https://docs.oracle.com/javase/10/docs/api/java/util/logging/Logger.html#entering(java.lang.String, java.lang.String, java.lang.Object)
• https://docs.oracle.com/javase/10/docs/api/java/util/logging/Logger.html#entering(java.lang.String, java.lang.String, java.lang.Object%5B%5D)