Tailer (Apache Commons IO 2.5 API)

java.lang.Object
- org.apache.commons.io.input.Tailer

All Implemented Interfaces:

Runnable
```
public class Tailer
extends Object
implements Runnable
```
Simple implementation of the unix "tail -f" functionality.
1. Create a TailerListener implementation

First you need to create a TailerListener implementation (TailerListenerAdapter is provided for convenience so that you don't have to implement every method).

For example:
```
  public class MyTailerListener extends TailerListenerAdapter {
      public void handle(String line) {
          System.out.println(line);
      }
  }
```
2. Using a Tailer

You can create and use a Tailer in one of three ways:
- Using one of the static helper methods:
- Using an Executor
- Using an Thread
An example of each of these is shown below.

2.1 Using the static helper method
```
      TailerListener listener = new MyTailerListener();
      Tailer tailer = Tailer.create(file, listener, delay);
```
2.2 Using an Executor
```
      TailerListener listener = new MyTailerListener();
      Tailer tailer = new Tailer(file, listener, delay);

      // stupid executor impl. for demo purposes
      Executor executor = new Executor() {
          public void execute(Runnable command) {
              command.run();
           }
      };

      executor.execute(tailer);
 
```
2.3 Using a Thread
```
      TailerListener listener = new MyTailerListener();
      Tailer tailer = new Tailer(file, listener, delay);
      Thread thread = new Thread(tailer);
      thread.setDaemon(true); // optional
      thread.start();
```
3. Stopping a Tailer

Remember to stop the tailer when you have done with it:
```
      tailer.stop();
 
```
4. Interrupting a Tailer

You can interrupt the thread a tailer is running on by calling Thread.interrupt().
```
      thread.interrupt();
 
```
If you interrupt a tailer, the tailer listener is called with the InterruptedException.

The file is read using the default charset; this can be overriden if necessary
Since:

2.0, 2.5 Updated behavior and documentation for Thread.interrupt()

Version:

$Id: Tailer.java 1714076 2015-11-12 16:06:41Z krosenvold $

See Also:
TailerListener, TailerListenerAdapter

Constructor Summary

Constructors
Constructor and Description
`Tailer(File file, Charset cset, TailerListener listener, long delayMillis, boolean end, boolean reOpen, int bufSize)` Creates a Tailer for the given file, with a specified buffer size.
`Tailer(File file, TailerListener listener)` Creates a Tailer for the given file, starting from the beginning, with the default delay of 1.0s.
`Tailer(File file, TailerListener listener, long delayMillis)` Creates a Tailer for the given file, starting from the beginning.
`Tailer(File file, TailerListener listener, long delayMillis, boolean end)` Creates a Tailer for the given file, with a delay other than the default 1.0s.
`Tailer(File file, TailerListener listener, long delayMillis, boolean end, boolean reOpen)` Creates a Tailer for the given file, with a delay other than the default 1.0s.
`Tailer(File file, TailerListener listener, long delayMillis, boolean end, boolean reOpen, int bufSize)` Creates a Tailer for the given file, with a specified buffer size.
`Tailer(File file, TailerListener listener, long delayMillis, boolean end, int bufSize)` Creates a Tailer for the given file, with a specified buffer size.

Method Summary

Methods
Modifier and Type	Method and Description
`static Tailer`	`create(File file, Charset charset, TailerListener listener, long delayMillis, boolean end, boolean reOpen, int bufSize)` Creates and starts a Tailer for the given file.
`static Tailer`	`create(File file, TailerListener listener)` Creates and starts a Tailer for the given file, starting at the beginning of the file with the default delay of 1.0s
`static Tailer`	`create(File file, TailerListener listener, long delayMillis)` Creates and starts a Tailer for the given file, starting at the beginning of the file
`static Tailer`	`create(File file, TailerListener listener, long delayMillis, boolean end)` Creates and starts a Tailer for the given file with default buffer size.
`static Tailer`	`create(File file, TailerListener listener, long delayMillis, boolean end, boolean reOpen)` Creates and starts a Tailer for the given file with default buffer size.
`static Tailer`	`create(File file, TailerListener listener, long delayMillis, boolean end, boolean reOpen, int bufSize)` Creates and starts a Tailer for the given file.
`static Tailer`	`create(File file, TailerListener listener, long delayMillis, boolean end, int bufSize)` Creates and starts a Tailer for the given file.
`long`	`getDelay()` Return the delay in milliseconds.
`File`	`getFile()` Return the file.
`protected boolean`	`getRun()` Gets whether to keep on running.
`void`	`run()` Follows changes in the file, calling the TailerListener's handle method for each new line.
`void`	`stop()` Allows the tailer to complete its current loop and return.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Tailer
```
public Tailer(File file,
      TailerListener listener)
```
    Creates a Tailer for the given file, starting from the beginning, with the default delay of 1.0s.
    
    Parameters:
    file - The file to follow.
    listener - the TailerListener to use.
  - Tailer
```
public Tailer(File file,
      TailerListener listener,
      long delayMillis)
```
    Creates a Tailer for the given file, starting from the beginning.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
  - Tailer
```
public Tailer(File file,
      TailerListener listener,
      long delayMillis,
      boolean end)
```
    Creates a Tailer for the given file, with a delay other than the default 1.0s.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
  - Tailer
```
public Tailer(File file,
      TailerListener listener,
      long delayMillis,
      boolean end,
      boolean reOpen)
```
    Creates a Tailer for the given file, with a delay other than the default 1.0s.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - if true, close and reopen the file between reading chunks
  - Tailer
```
public Tailer(File file,
      TailerListener listener,
      long delayMillis,
      boolean end,
      int bufSize)
```
    Creates a Tailer for the given file, with a specified buffer size.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    bufSize - Buffer size
  - Tailer
```
public Tailer(File file,
      TailerListener listener,
      long delayMillis,
      boolean end,
      boolean reOpen,
      int bufSize)
```
    Creates a Tailer for the given file, with a specified buffer size.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - if true, close and reopen the file between reading chunks
    bufSize - Buffer size
  - Tailer
```
public Tailer(File file,
      Charset cset,
      TailerListener listener,
      long delayMillis,
      boolean end,
      boolean reOpen,
      int bufSize)
```
    Creates a Tailer for the given file, with a specified buffer size.
    
    Parameters:
    file - the file to follow.
    cset - the Charset to be used for reading the file
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - if true, close and reopen the file between reading chunks
    bufSize - Buffer size
- Method Detail
  - create
```
public static Tailer create(File file,
            TailerListener listener,
            long delayMillis,
            boolean end,
            int bufSize)
```
    Creates and starts a Tailer for the given file.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    bufSize - buffer size.
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            TailerListener listener,
            long delayMillis,
            boolean end,
            boolean reOpen,
            int bufSize)
```
    Creates and starts a Tailer for the given file.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - whether to close/reopen the file between chunks
    bufSize - buffer size.
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            Charset charset,
            TailerListener listener,
            long delayMillis,
            boolean end,
            boolean reOpen,
            int bufSize)
```
    Creates and starts a Tailer for the given file.
    
    Parameters:
    file - the file to follow.
    charset - the character set to use for reading the file
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - whether to close/reopen the file between chunks
    bufSize - buffer size.
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            TailerListener listener,
            long delayMillis,
            boolean end)
```
    Creates and starts a Tailer for the given file with default buffer size.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            TailerListener listener,
            long delayMillis,
            boolean end,
            boolean reOpen)
```
    Creates and starts a Tailer for the given file with default buffer size.
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    end - Set to true to tail from the end of the file, false to tail from the beginning of the file.
    reOpen - whether to close/reopen the file between chunks
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            TailerListener listener,
            long delayMillis)
```
    Creates and starts a Tailer for the given file, starting at the beginning of the file
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    delayMillis - the delay between checks of the file for new content in milliseconds.
    
    Returns:
    The new tailer
  - create
```
public static Tailer create(File file,
            TailerListener listener)
```
    Creates and starts a Tailer for the given file, starting at the beginning of the file with the default delay of 1.0s
    
    Parameters:
    file - the file to follow.
    listener - the TailerListener to use.
    
    Returns:
    The new tailer
  - getFile
```
public File getFile()
```
    Return the file.
    
    Returns:
    the file
  - getRun
```
protected boolean getRun()
```
    Gets whether to keep on running.
    
    Returns:
    whether to keep on running.
    Since:
    
    2.5
  - getDelay
```
public long getDelay()
```
    Return the delay in milliseconds.
    
    Returns:
    the delay in milliseconds.
  - run
```
public void run()
```
    Follows changes in the file, calling the TailerListener's handle method for each new line.
    
    Specified by:
    
    run in interface Runnable
  - stop
```
public void stop()
```
    Allows the tailer to complete its current loop and return.

Class Tailer

1. Create a TailerListener implementation

2. Using a Tailer

2.1 Using the static helper method

2.2 Using an Executor

2.3 Using a Thread

3. Stopping a Tailer

4. Interrupting a Tailer

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Tailer

Tailer

Tailer

Tailer

Tailer

Tailer

Tailer

Method Detail

create

create

create

create

create

create

create

getFile

getRun

getDelay

run

stop