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## org.apache.poi.util
Class POILogger

    java.lang.Object
      org.apache.poi.util.POILogger

Direct Known Subclasses:
  CommonsLogger, NullLogger, SystemOutLogger

    @Internal
    public abstract class POILogger

extends java.lang.Object

A logger interface that strives to make it as easy as possible for developers to write log calls, while simultaneously making those calls as cheap as possible by performing lazy evaluation of the log message.

Field Summary
`static int` | `DEBUG`
`static int` | `ERROR`
`static int` | `FATAL`
`static int` | `INFO`
`protected static java.lang.String[]` | `LEVEL_STRINGS` Long strings for numeric log level.
`protected static java.lang.String[]` | `LEVEL_STRINGS_SHORT` Short strings for numeric log level.
`static int` | `WARN`

Method Summary
`protected abstract void` | `_log(int level, java.lang.Object obj1)` Log a message
`protected abstract void` | `_log(int level, java.lang.Object obj1, java.lang.Throwable exception)` Log a message
`abstract boolean` | `check(int level)` Check if a logger is enabled to log at the specified level This allows code to avoid building strings or evaluating functions in the arguments to log.
`abstract void` | `initialize(java.lang.String cat)`
`void` | `log(int level, java.lang.Object... objs)` Log a message.

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

Field Detail

### DEBUG

    public static final int DEBUG

See Also:
  Constant Field Values

### INFO

    public static final int INFO

See Also:
  Constant Field Values

### WARN

    public static final int WARN

See Also:
  Constant Field Values

### ERROR

    public static final int ERROR

See Also:
  Constant Field Values

### FATAL

    public static final int FATAL

See Also:
  Constant Field Values

### LEVEL_STRINGS_SHORT

    protected static final java.lang.String[] LEVEL_STRINGS_SHORT

  Short strings for numeric log level. Use level as array index.

### LEVEL_STRINGS

    protected static final java.lang.String[] LEVEL_STRINGS

  Long strings for numeric log level. Use level as array index.

Method Detail

### initialize

    public abstract void initialize(java.lang.String cat)

### _log

    protected abstract void _log(int level,
                                 java.lang.Object obj1)

  Log a message

  Parameters:
    `level` - One of DEBUG, INFO, WARN, ERROR, FATAL
    `obj1` - The object to log. This is converted to a string.

### _log

    protected abstract void _log(int level,
                                 java.lang.Object obj1,
                                 java.lang.Throwable exception)

  Log a message

  Parameters:
    `level` - One of DEBUG, INFO, WARN, ERROR, FATAL
    `obj1` - The object to log. This is converted to a string.
    `exception` - An exception to be logged

### check

    public abstract boolean check(int level)

  Check if a logger is enabled to log at the specified level This allows code to avoid building strings or evaluating functions in the arguments to log. An example: `

       if (logger.check(POILogger.INFO)) {
           logger.log(POILogger.INFO, "Avoid concatenating " + " strings and evaluating " + functions());
       }

  `

  Parameters:
    `level` - One of DEBUG, INFO, WARN, ERROR, FATAL

### log

    public void log(int level,
                    java.lang.Object... objs)

  Log a message. Lazily appends Object parameters together. If the last parameter is a `Throwable` it is logged specially.

  Parameters:
    `level` - One of DEBUG, INFO, WARN, ERROR, FATAL
    `objs` - the objects to place in the message

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Copyright 2017 The Apache Software Foundation or its licensors, as applicable.